1/*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#include "precompiled.hpp"
26#include "jvm.h"
27#include "aot/aotLoader.hpp"
28#include "classfile/classLoader.hpp"
29#include "classfile/javaClasses.hpp"
30#include "classfile/moduleEntry.hpp"
31#include "classfile/systemDictionary.hpp"
32#include "classfile/vmSymbols.hpp"
33#include "code/codeCache.hpp"
34#include "code/scopeDesc.hpp"
35#include "compiler/compileBroker.hpp"
36#include "compiler/compileTask.hpp"
37#include "gc/shared/barrierSet.hpp"
38#include "gc/shared/gcId.hpp"
39#include "gc/shared/gcLocker.inline.hpp"
40#include "gc/shared/workgroup.hpp"
41#include "interpreter/interpreter.hpp"
42#include "interpreter/linkResolver.hpp"
43#include "interpreter/oopMapCache.hpp"
44#include "jfr/jfrEvents.hpp"
45#include "jvmtifiles/jvmtiEnv.hpp"
46#include "logging/log.hpp"
47#include "logging/logConfiguration.hpp"
48#include "logging/logStream.hpp"
49#include "memory/allocation.inline.hpp"
50#include "memory/metaspaceShared.hpp"
51#include "memory/oopFactory.hpp"
52#include "memory/resourceArea.hpp"
53#include "memory/universe.hpp"
54#include "oops/access.inline.hpp"
55#include "oops/instanceKlass.hpp"
56#include "oops/objArrayOop.hpp"
57#include "oops/oop.inline.hpp"
58#include "oops/symbol.hpp"
59#include "oops/typeArrayOop.inline.hpp"
60#include "oops/verifyOopClosure.hpp"
61#include "prims/jvm_misc.hpp"
62#include "prims/jvmtiExport.hpp"
63#include "prims/jvmtiThreadState.hpp"
64#include "runtime/arguments.hpp"
65#include "runtime/atomic.hpp"
66#include "runtime/biasedLocking.hpp"
67#include "runtime/fieldDescriptor.inline.hpp"
68#include "runtime/flags/jvmFlagConstraintList.hpp"
69#include "runtime/flags/jvmFlagRangeList.hpp"
70#include "runtime/flags/jvmFlagWriteableList.hpp"
71#include "runtime/deoptimization.hpp"
72#include "runtime/frame.inline.hpp"
73#include "runtime/handles.inline.hpp"
74#include "runtime/handshake.hpp"
75#include "runtime/init.hpp"
76#include "runtime/interfaceSupport.inline.hpp"
77#include "runtime/java.hpp"
78#include "runtime/javaCalls.hpp"
79#include "runtime/jniHandles.inline.hpp"
80#include "runtime/jniPeriodicChecker.hpp"
81#include "runtime/memprofiler.hpp"
82#include "runtime/mutexLocker.hpp"
83#include "runtime/objectMonitor.hpp"
84#include "runtime/orderAccess.hpp"
85#include "runtime/osThread.hpp"
86#include "runtime/prefetch.inline.hpp"
87#include "runtime/safepoint.hpp"
88#include "runtime/safepointMechanism.inline.hpp"
89#include "runtime/safepointVerifiers.hpp"
90#include "runtime/sharedRuntime.hpp"
91#include "runtime/statSampler.hpp"
92#include "runtime/stubRoutines.hpp"
93#include "runtime/sweeper.hpp"
94#include "runtime/task.hpp"
95#include "runtime/thread.inline.hpp"
96#include "runtime/threadCritical.hpp"
97#include "runtime/threadSMR.inline.hpp"
98#include "runtime/threadStatisticalInfo.hpp"
99#include "runtime/timer.hpp"
100#include "runtime/timerTrace.hpp"
101#include "runtime/vframe.inline.hpp"
102#include "runtime/vframeArray.hpp"
103#include "runtime/vframe_hp.hpp"
104#include "runtime/vmThread.hpp"
105#include "runtime/vmOperations.hpp"
106#include "runtime/vm_version.hpp"
107#include "services/attachListener.hpp"
108#include "services/management.hpp"
109#include "services/memTracker.hpp"
110#include "services/threadService.hpp"
111#include "utilities/align.hpp"
112#include "utilities/copy.hpp"
113#include "utilities/defaultStream.hpp"
114#include "utilities/dtrace.hpp"
115#include "utilities/events.hpp"
116#include "utilities/macros.hpp"
117#include "utilities/preserveException.hpp"
118#include "utilities/singleWriterSynchronizer.hpp"
119#include "utilities/vmError.hpp"
120#if INCLUDE_JVMCI
121#include "jvmci/jvmci.hpp"
122#include "jvmci/jvmciEnv.hpp"
123#endif
124#ifdef COMPILER1
125#include "c1/c1_Compiler.hpp"
126#endif
127#ifdef COMPILER2
128#include "opto/c2compiler.hpp"
129#include "opto/idealGraphPrinter.hpp"
130#endif
131#if INCLUDE_RTM_OPT
132#include "runtime/rtmLocking.hpp"
133#endif
134#if INCLUDE_JFR
135#include "jfr/jfr.hpp"
136#endif
137
138// Initialization after module runtime initialization
139void universe_post_module_init(); // must happen after call_initPhase2
140
141#ifdef DTRACE_ENABLED
142
143// Only bother with this argument setup if dtrace is available
144
145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
147
148 #define DTRACE_THREAD_PROBE(probe, javathread) \
149 { \
150 ResourceMark rm(this); \
151 int len = 0; \
152 const char* name = (javathread)->get_thread_name(); \
153 len = strlen(name); \
154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
155 (char *) name, len, \
156 java_lang_Thread::thread_id((javathread)->threadObj()), \
157 (uintptr_t) (javathread)->osthread()->thread_id(), \
158 java_lang_Thread::is_daemon((javathread)->threadObj())); \
159 }
160
161#else // ndef DTRACE_ENABLED
162
163 #define DTRACE_THREAD_PROBE(probe, javathread)
164
165#endif // ndef DTRACE_ENABLED
166
167#ifndef USE_LIBRARY_BASED_TLS_ONLY
168// Current thread is maintained as a thread-local variable
169THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL;
170#endif
171
172// ======= Thread ========
173// Support for forcing alignment of thread objects for biased locking
174void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
175 if (UseBiasedLocking) {
176 const int alignment = markOopDesc::biased_lock_alignment;
177 size_t aligned_size = size + (alignment - sizeof(intptr_t));
178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
179 : AllocateHeap(aligned_size, flags, CURRENT_PC,
180 AllocFailStrategy::RETURN_NULL);
181 void* aligned_addr = align_up(real_malloc_addr, alignment);
182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
184 "JavaThread alignment code overflowed allocated storage");
185 if (aligned_addr != real_malloc_addr) {
186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
187 p2i(real_malloc_addr),
188 p2i(aligned_addr));
189 }
190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
191 return aligned_addr;
192 } else {
193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
195 }
196}
197
198void Thread::operator delete(void* p) {
199 if (UseBiasedLocking) {
200 FreeHeap(((Thread*) p)->_real_malloc_address);
201 } else {
202 FreeHeap(p);
203 }
204}
205
206void JavaThread::smr_delete() {
207 if (_on_thread_list) {
208 ThreadsSMRSupport::smr_delete(this);
209 } else {
210 delete this;
211 }
212}
213
214// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
215// JavaThread
216
217DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;)
218
219Thread::Thread() {
220
221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;)
222
223 // stack and get_thread
224 set_stack_base(NULL);
225 set_stack_size(0);
226 set_self_raw_id(0);
227 set_lgrp_id(-1);
228 DEBUG_ONLY(clear_suspendible_thread();)
229
230 // allocated data structures
231 set_osthread(NULL);
232 set_resource_area(new (mtThread)ResourceArea());
233 DEBUG_ONLY(_current_resource_mark = NULL;)
234 set_handle_area(new (mtThread) HandleArea(NULL));
235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
236 set_active_handles(NULL);
237 set_free_handle_block(NULL);
238 set_last_handle_mark(NULL);
239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL);
240
241 // Initial value of zero ==> never claimed.
242 _threads_do_token = 0;
243 _threads_hazard_ptr = NULL;
244 _threads_list_ptr = NULL;
245 _nested_threads_hazard_ptr_cnt = 0;
246 _rcu_counter = 0;
247
248 // the handle mark links itself to last_handle_mark
249 new HandleMark(this);
250
251 // plain initialization
252 debug_only(_owned_locks = NULL;)
253 debug_only(_allow_allocation_count = 0;)
254 NOT_PRODUCT(_allow_safepoint_count = 0;)
255 NOT_PRODUCT(_skip_gcalot = false;)
256 _jvmti_env_iteration_count = 0;
257 set_allocated_bytes(0);
258 _vm_operation_started_count = 0;
259 _vm_operation_completed_count = 0;
260 _current_pending_monitor = NULL;
261 _current_pending_monitor_is_from_java = true;
262 _current_waiting_monitor = NULL;
263 _num_nested_signal = 0;
264 omFreeList = NULL;
265 omFreeCount = 0;
266 omFreeProvision = 32;
267 omInUseList = NULL;
268 omInUseCount = 0;
269
270#ifdef ASSERT
271 _visited_for_critical_count = false;
272#endif
273
274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
275 Monitor::_safepoint_check_sometimes);
276 _suspend_flags = 0;
277
278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
279 _hashStateX = os::random();
280 _hashStateY = 842502087;
281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
282 _hashStateW = 273326509;
283
284 _OnTrap = 0;
285 _Stalled = 0;
286 _TypeTag = 0x2BAD;
287
288 // Many of the following fields are effectively final - immutable
289 // Note that nascent threads can't use the Native Monitor-Mutex
290 // construct until the _MutexEvent is initialized ...
291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
292 // we might instead use a stack of ParkEvents that we could provision on-demand.
293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
294 // and ::Release()
295 _ParkEvent = ParkEvent::Allocate(this);
296 _SleepEvent = ParkEvent::Allocate(this);
297 _MuxEvent = ParkEvent::Allocate(this);
298
299#ifdef CHECK_UNHANDLED_OOPS
300 if (CheckUnhandledOops) {
301 _unhandled_oops = new UnhandledOops(this);
302 }
303#endif // CHECK_UNHANDLED_OOPS
304#ifdef ASSERT
305 if (UseBiasedLocking) {
306 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
307 assert(this == _real_malloc_address ||
308 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment),
309 "bug in forced alignment of thread objects");
310 }
311#endif // ASSERT
312
313 // Notify the barrier set that a thread is being created. The initial
314 // thread is created before the barrier set is available. The call to
315 // BarrierSet::on_thread_create() for this thread is therefore deferred
316 // to BarrierSet::set_barrier_set().
317 BarrierSet* const barrier_set = BarrierSet::barrier_set();
318 if (barrier_set != NULL) {
319 barrier_set->on_thread_create(this);
320 } else {
321 // Only the main thread should be created before the barrier set
322 // and that happens just before Thread::current is set. No other thread
323 // can attach as the VM is not created yet, so they can't execute this code.
324 // If the main thread creates other threads before the barrier set that is an error.
325 assert(Thread::current_or_null() == NULL, "creating thread before barrier set");
326 }
327}
328
329void Thread::initialize_thread_current() {
330#ifndef USE_LIBRARY_BASED_TLS_ONLY
331 assert(_thr_current == NULL, "Thread::current already initialized");
332 _thr_current = this;
333#endif
334 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized");
335 ThreadLocalStorage::set_thread(this);
336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
337}
338
339void Thread::clear_thread_current() {
340 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!");
341#ifndef USE_LIBRARY_BASED_TLS_ONLY
342 _thr_current = NULL;
343#endif
344 ThreadLocalStorage::set_thread(NULL);
345}
346
347void Thread::record_stack_base_and_size() {
348 // Note: at this point, Thread object is not yet initialized. Do not rely on
349 // any members being initialized. Do not rely on Thread::current() being set.
350 // If possible, refrain from doing anything which may crash or assert since
351 // quite probably those crash dumps will be useless.
352 set_stack_base(os::current_stack_base());
353 set_stack_size(os::current_stack_size());
354
355#ifdef SOLARIS
356 if (os::is_primordial_thread()) {
357 os::Solaris::correct_stack_boundaries_for_primordial_thread(this);
358 }
359#endif
360
361 // Set stack limits after thread is initialized.
362 if (is_Java_thread()) {
363 ((JavaThread*) this)->set_stack_overflow_limit();
364 ((JavaThread*) this)->set_reserved_stack_activation(stack_base());
365 }
366}
367
368#if INCLUDE_NMT
369void Thread::register_thread_stack_with_NMT() {
370 MemTracker::record_thread_stack(stack_end(), stack_size());
371}
372#endif // INCLUDE_NMT
373
374void Thread::call_run() {
375 DEBUG_ONLY(_run_state = CALL_RUN;)
376
377 // At this point, Thread object should be fully initialized and
378 // Thread::current() should be set.
379
380 assert(Thread::current_or_null() != NULL, "current thread is unset");
381 assert(Thread::current_or_null() == this, "current thread is wrong");
382
383 // Perform common initialization actions
384
385 register_thread_stack_with_NMT();
386
387 JFR_ONLY(Jfr::on_thread_start(this);)
388
389 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: "
390 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).",
391 os::current_thread_id(), p2i(stack_base() - stack_size()),
392 p2i(stack_base()), stack_size()/1024);
393
394 // Perform <ChildClass> initialization actions
395 DEBUG_ONLY(_run_state = PRE_RUN;)
396 this->pre_run();
397
398 // Invoke <ChildClass>::run()
399 DEBUG_ONLY(_run_state = RUN;)
400 this->run();
401 // Returned from <ChildClass>::run(). Thread finished.
402
403 // Perform common tear-down actions
404
405 assert(Thread::current_or_null() != NULL, "current thread is unset");
406 assert(Thread::current_or_null() == this, "current thread is wrong");
407
408 // Perform <ChildClass> tear-down actions
409 DEBUG_ONLY(_run_state = POST_RUN;)
410 this->post_run();
411
412 // Note: at this point the thread object may already have deleted itself,
413 // so from here on do not dereference *this*. Not all thread types currently
414 // delete themselves when they terminate. But no thread should ever be deleted
415 // asynchronously with respect to its termination - that is what _run_state can
416 // be used to check.
417
418 assert(Thread::current_or_null() == NULL, "current thread still present");
419}
420
421Thread::~Thread() {
422
423 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually
424 // get started due to errors etc. Any active thread should at least reach post_run
425 // before it is deleted (usually in post_run()).
426 assert(_run_state == PRE_CALL_RUN ||
427 _run_state == POST_RUN, "Active Thread deleted before post_run(): "
428 "_run_state=%d", (int)_run_state);
429
430 // Notify the barrier set that a thread is being destroyed. Note that a barrier
431 // set might not be available if we encountered errors during bootstrapping.
432 BarrierSet* const barrier_set = BarrierSet::barrier_set();
433 if (barrier_set != NULL) {
434 barrier_set->on_thread_destroy(this);
435 }
436
437 // stack_base can be NULL if the thread is never started or exited before
438 // record_stack_base_and_size called. Although, we would like to ensure
439 // that all started threads do call record_stack_base_and_size(), there is
440 // not proper way to enforce that.
441#if INCLUDE_NMT
442 if (_stack_base != NULL) {
443 MemTracker::release_thread_stack(stack_end(), stack_size());
444#ifdef ASSERT
445 set_stack_base(NULL);
446#endif
447 }
448#endif // INCLUDE_NMT
449
450 // deallocate data structures
451 delete resource_area();
452 // since the handle marks are using the handle area, we have to deallocated the root
453 // handle mark before deallocating the thread's handle area,
454 assert(last_handle_mark() != NULL, "check we have an element");
455 delete last_handle_mark();
456 assert(last_handle_mark() == NULL, "check we have reached the end");
457
458 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
459 // We NULL out the fields for good hygiene.
460 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
461 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
462 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
463
464 delete handle_area();
465 delete metadata_handles();
466
467 // SR_handler uses this as a termination indicator -
468 // needs to happen before os::free_thread()
469 delete _SR_lock;
470 _SR_lock = NULL;
471
472 // osthread() can be NULL, if creation of thread failed.
473 if (osthread() != NULL) os::free_thread(osthread());
474
475 // Clear Thread::current if thread is deleting itself and it has not
476 // already been done. This must be done before the memory is deallocated.
477 // Needed to ensure JNI correctly detects non-attached threads.
478 if (this == Thread::current_or_null()) {
479 Thread::clear_thread_current();
480 }
481
482 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
483}
484
485#ifdef ASSERT
486// A JavaThread is considered "dangling" if it is not the current
487// thread, has been added the Threads list, the system is not at a
488// safepoint and the Thread is not "protected".
489//
490void Thread::check_for_dangling_thread_pointer(Thread *thread) {
491 assert(!thread->is_Java_thread() || Thread::current() == thread ||
492 !((JavaThread *) thread)->on_thread_list() ||
493 SafepointSynchronize::is_at_safepoint() ||
494 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
495 "possibility of dangling Thread pointer");
496}
497#endif
498
499ThreadPriority Thread::get_priority(const Thread* const thread) {
500 ThreadPriority priority;
501 // Can return an error!
502 (void)os::get_priority(thread, priority);
503 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
504 return priority;
505}
506
507void Thread::set_priority(Thread* thread, ThreadPriority priority) {
508 debug_only(check_for_dangling_thread_pointer(thread);)
509 // Can return an error!
510 (void)os::set_priority(thread, priority);
511}
512
513
514void Thread::start(Thread* thread) {
515 // Start is different from resume in that its safety is guaranteed by context or
516 // being called from a Java method synchronized on the Thread object.
517 if (!DisableStartThread) {
518 if (thread->is_Java_thread()) {
519 // Initialize the thread state to RUNNABLE before starting this thread.
520 // Can not set it after the thread started because we do not know the
521 // exact thread state at that time. It could be in MONITOR_WAIT or
522 // in SLEEPING or some other state.
523 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
524 java_lang_Thread::RUNNABLE);
525 }
526 os::start_thread(thread);
527 }
528}
529
530// Enqueue a VM_Operation to do the job for us - sometime later
531void Thread::send_async_exception(oop java_thread, oop java_throwable) {
532 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
533 VMThread::execute(vm_stop);
534}
535
536
537// Check if an external suspend request has completed (or has been
538// cancelled). Returns true if the thread is externally suspended and
539// false otherwise.
540//
541// The bits parameter returns information about the code path through
542// the routine. Useful for debugging:
543//
544// set in is_ext_suspend_completed():
545// 0x00000001 - routine was entered
546// 0x00000010 - routine return false at end
547// 0x00000100 - thread exited (return false)
548// 0x00000200 - suspend request cancelled (return false)
549// 0x00000400 - thread suspended (return true)
550// 0x00001000 - thread is in a suspend equivalent state (return true)
551// 0x00002000 - thread is native and walkable (return true)
552// 0x00004000 - thread is native_trans and walkable (needed retry)
553//
554// set in wait_for_ext_suspend_completion():
555// 0x00010000 - routine was entered
556// 0x00020000 - suspend request cancelled before loop (return false)
557// 0x00040000 - thread suspended before loop (return true)
558// 0x00080000 - suspend request cancelled in loop (return false)
559// 0x00100000 - thread suspended in loop (return true)
560// 0x00200000 - suspend not completed during retry loop (return false)
561
562// Helper class for tracing suspend wait debug bits.
563//
564// 0x00000100 indicates that the target thread exited before it could
565// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
566// 0x00080000 each indicate a cancelled suspend request so they don't
567// count as wait failures either.
568#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
569
570class TraceSuspendDebugBits : public StackObj {
571 private:
572 JavaThread * jt;
573 bool is_wait;
574 bool called_by_wait; // meaningful when !is_wait
575 uint32_t * bits;
576
577 public:
578 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
579 uint32_t *_bits) {
580 jt = _jt;
581 is_wait = _is_wait;
582 called_by_wait = _called_by_wait;
583 bits = _bits;
584 }
585
586 ~TraceSuspendDebugBits() {
587 if (!is_wait) {
588#if 1
589 // By default, don't trace bits for is_ext_suspend_completed() calls.
590 // That trace is very chatty.
591 return;
592#else
593 if (!called_by_wait) {
594 // If tracing for is_ext_suspend_completed() is enabled, then only
595 // trace calls to it from wait_for_ext_suspend_completion()
596 return;
597 }
598#endif
599 }
600
601 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
602 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
603 MutexLocker ml(Threads_lock); // needed for get_thread_name()
604 ResourceMark rm;
605
606 tty->print_cr(
607 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
608 jt->get_thread_name(), *bits);
609
610 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
611 }
612 }
613 }
614};
615#undef DEBUG_FALSE_BITS
616
617
618bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
619 uint32_t *bits) {
620 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
621
622 bool did_trans_retry = false; // only do thread_in_native_trans retry once
623 bool do_trans_retry; // flag to force the retry
624
625 *bits |= 0x00000001;
626
627 do {
628 do_trans_retry = false;
629
630 if (is_exiting()) {
631 // Thread is in the process of exiting. This is always checked
632 // first to reduce the risk of dereferencing a freed JavaThread.
633 *bits |= 0x00000100;
634 return false;
635 }
636
637 if (!is_external_suspend()) {
638 // Suspend request is cancelled. This is always checked before
639 // is_ext_suspended() to reduce the risk of a rogue resume
640 // confusing the thread that made the suspend request.
641 *bits |= 0x00000200;
642 return false;
643 }
644
645 if (is_ext_suspended()) {
646 // thread is suspended
647 *bits |= 0x00000400;
648 return true;
649 }
650
651 // Now that we no longer do hard suspends of threads running
652 // native code, the target thread can be changing thread state
653 // while we are in this routine:
654 //
655 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
656 //
657 // We save a copy of the thread state as observed at this moment
658 // and make our decision about suspend completeness based on the
659 // copy. This closes the race where the thread state is seen as
660 // _thread_in_native_trans in the if-thread_blocked check, but is
661 // seen as _thread_blocked in if-thread_in_native_trans check.
662 JavaThreadState save_state = thread_state();
663
664 if (save_state == _thread_blocked && is_suspend_equivalent()) {
665 // If the thread's state is _thread_blocked and this blocking
666 // condition is known to be equivalent to a suspend, then we can
667 // consider the thread to be externally suspended. This means that
668 // the code that sets _thread_blocked has been modified to do
669 // self-suspension if the blocking condition releases. We also
670 // used to check for CONDVAR_WAIT here, but that is now covered by
671 // the _thread_blocked with self-suspension check.
672 //
673 // Return true since we wouldn't be here unless there was still an
674 // external suspend request.
675 *bits |= 0x00001000;
676 return true;
677 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
678 // Threads running native code will self-suspend on native==>VM/Java
679 // transitions. If its stack is walkable (should always be the case
680 // unless this function is called before the actual java_suspend()
681 // call), then the wait is done.
682 *bits |= 0x00002000;
683 return true;
684 } else if (!called_by_wait && !did_trans_retry &&
685 save_state == _thread_in_native_trans &&
686 frame_anchor()->walkable()) {
687 // The thread is transitioning from thread_in_native to another
688 // thread state. check_safepoint_and_suspend_for_native_trans()
689 // will force the thread to self-suspend. If it hasn't gotten
690 // there yet we may have caught the thread in-between the native
691 // code check above and the self-suspend. Lucky us. If we were
692 // called by wait_for_ext_suspend_completion(), then it
693 // will be doing the retries so we don't have to.
694 //
695 // Since we use the saved thread state in the if-statement above,
696 // there is a chance that the thread has already transitioned to
697 // _thread_blocked by the time we get here. In that case, we will
698 // make a single unnecessary pass through the logic below. This
699 // doesn't hurt anything since we still do the trans retry.
700
701 *bits |= 0x00004000;
702
703 // Once the thread leaves thread_in_native_trans for another
704 // thread state, we break out of this retry loop. We shouldn't
705 // need this flag to prevent us from getting back here, but
706 // sometimes paranoia is good.
707 did_trans_retry = true;
708
709 // We wait for the thread to transition to a more usable state.
710 for (int i = 1; i <= SuspendRetryCount; i++) {
711 // We used to do an "os::yield_all(i)" call here with the intention
712 // that yielding would increase on each retry. However, the parameter
713 // is ignored on Linux which means the yield didn't scale up. Waiting
714 // on the SR_lock below provides a much more predictable scale up for
715 // the delay. It also provides a simple/direct point to check for any
716 // safepoint requests from the VMThread
717
718 // temporarily drops SR_lock while doing wait with safepoint check
719 // (if we're a JavaThread - the WatcherThread can also call this)
720 // and increase delay with each retry
721 if (Thread::current()->is_Java_thread()) {
722 SR_lock()->wait(i * delay);
723 } else {
724 SR_lock()->wait_without_safepoint_check(i * delay);
725 }
726
727 // check the actual thread state instead of what we saved above
728 if (thread_state() != _thread_in_native_trans) {
729 // the thread has transitioned to another thread state so
730 // try all the checks (except this one) one more time.
731 do_trans_retry = true;
732 break;
733 }
734 } // end retry loop
735
736
737 }
738 } while (do_trans_retry);
739
740 *bits |= 0x00000010;
741 return false;
742}
743
744// Wait for an external suspend request to complete (or be cancelled).
745// Returns true if the thread is externally suspended and false otherwise.
746//
747bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
748 uint32_t *bits) {
749 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
750 false /* !called_by_wait */, bits);
751
752 // local flag copies to minimize SR_lock hold time
753 bool is_suspended;
754 bool pending;
755 uint32_t reset_bits;
756
757 // set a marker so is_ext_suspend_completed() knows we are the caller
758 *bits |= 0x00010000;
759
760 // We use reset_bits to reinitialize the bits value at the top of
761 // each retry loop. This allows the caller to make use of any
762 // unused bits for their own marking purposes.
763 reset_bits = *bits;
764
765 {
766 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
767 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
768 delay, bits);
769 pending = is_external_suspend();
770 }
771 // must release SR_lock to allow suspension to complete
772
773 if (!pending) {
774 // A cancelled suspend request is the only false return from
775 // is_ext_suspend_completed() that keeps us from entering the
776 // retry loop.
777 *bits |= 0x00020000;
778 return false;
779 }
780
781 if (is_suspended) {
782 *bits |= 0x00040000;
783 return true;
784 }
785
786 for (int i = 1; i <= retries; i++) {
787 *bits = reset_bits; // reinit to only track last retry
788
789 // We used to do an "os::yield_all(i)" call here with the intention
790 // that yielding would increase on each retry. However, the parameter
791 // is ignored on Linux which means the yield didn't scale up. Waiting
792 // on the SR_lock below provides a much more predictable scale up for
793 // the delay. It also provides a simple/direct point to check for any
794 // safepoint requests from the VMThread
795
796 {
797 Thread* t = Thread::current();
798 MonitorLocker ml(SR_lock(),
799 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag);
800 // wait with safepoint check (if we're a JavaThread - the WatcherThread
801 // can also call this) and increase delay with each retry
802 ml.wait(i * delay);
803
804 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
805 delay, bits);
806
807 // It is possible for the external suspend request to be cancelled
808 // (by a resume) before the actual suspend operation is completed.
809 // Refresh our local copy to see if we still need to wait.
810 pending = is_external_suspend();
811 }
812
813 if (!pending) {
814 // A cancelled suspend request is the only false return from
815 // is_ext_suspend_completed() that keeps us from staying in the
816 // retry loop.
817 *bits |= 0x00080000;
818 return false;
819 }
820
821 if (is_suspended) {
822 *bits |= 0x00100000;
823 return true;
824 }
825 } // end retry loop
826
827 // thread did not suspend after all our retries
828 *bits |= 0x00200000;
829 return false;
830}
831
832// Called from API entry points which perform stack walking. If the
833// associated JavaThread is the current thread, then wait_for_suspend
834// is not used. Otherwise, it determines if we should wait for the
835// "other" thread to complete external suspension. (NOTE: in future
836// releases the suspension mechanism should be reimplemented so this
837// is not necessary.)
838//
839bool
840JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
841 if (this != JavaThread::current()) {
842 // "other" threads require special handling.
843 if (wait_for_suspend) {
844 // We are allowed to wait for the external suspend to complete
845 // so give the other thread a chance to get suspended.
846 if (!wait_for_ext_suspend_completion(SuspendRetryCount,
847 SuspendRetryDelay, bits)) {
848 // Didn't make it so let the caller know.
849 return false;
850 }
851 }
852 // We aren't allowed to wait for the external suspend to complete
853 // so if the other thread isn't externally suspended we need to
854 // let the caller know.
855 else if (!is_ext_suspend_completed_with_lock(bits)) {
856 return false;
857 }
858 }
859
860 return true;
861}
862
863#ifndef PRODUCT
864void JavaThread::record_jump(address target, address instr, const char* file,
865 int line) {
866
867 // This should not need to be atomic as the only way for simultaneous
868 // updates is via interrupts. Even then this should be rare or non-existent
869 // and we don't care that much anyway.
870
871 int index = _jmp_ring_index;
872 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
873 _jmp_ring[index]._target = (intptr_t) target;
874 _jmp_ring[index]._instruction = (intptr_t) instr;
875 _jmp_ring[index]._file = file;
876 _jmp_ring[index]._line = line;
877}
878#endif // PRODUCT
879
880void Thread::interrupt(Thread* thread) {
881 debug_only(check_for_dangling_thread_pointer(thread);)
882 os::interrupt(thread);
883}
884
885bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
886 debug_only(check_for_dangling_thread_pointer(thread);)
887 // Note: If clear_interrupted==false, this simply fetches and
888 // returns the value of the field osthread()->interrupted().
889 return os::is_interrupted(thread, clear_interrupted);
890}
891
892
893// GC Support
894bool Thread::claim_par_threads_do(uintx claim_token) {
895 uintx token = _threads_do_token;
896 if (token != claim_token) {
897 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token);
898 if (res == token) {
899 return true;
900 }
901 guarantee(res == claim_token, "invariant");
902 }
903 return false;
904}
905
906void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
907 active_handles()->oops_do(f);
908 // Do oop for ThreadShadow
909 f->do_oop((oop*)&_pending_exception);
910 handle_area()->oops_do(f);
911
912 // We scan thread local monitor lists here, and the remaining global
913 // monitors in ObjectSynchronizer::oops_do().
914 ObjectSynchronizer::thread_local_used_oops_do(this, f);
915}
916
917void Thread::metadata_handles_do(void f(Metadata*)) {
918 // Only walk the Handles in Thread.
919 if (metadata_handles() != NULL) {
920 for (int i = 0; i< metadata_handles()->length(); i++) {
921 f(metadata_handles()->at(i));
922 }
923 }
924}
925
926void Thread::print_on(outputStream* st, bool print_extended_info) const {
927 // get_priority assumes osthread initialized
928 if (osthread() != NULL) {
929 int os_prio;
930 if (os::get_native_priority(this, &os_prio) == OS_OK) {
931 st->print("os_prio=%d ", os_prio);
932 }
933
934 st->print("cpu=%.2fms ",
935 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0
936 );
937 st->print("elapsed=%.2fs ",
938 _statistical_info.getElapsedTime() / 1000.0
939 );
940 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) {
941 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes();
942 st->print("allocated=" SIZE_FORMAT "%s ",
943 byte_size_in_proper_unit(allocated_bytes),
944 proper_unit_for_byte_size(allocated_bytes)
945 );
946 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount());
947 }
948
949 st->print("tid=" INTPTR_FORMAT " ", p2i(this));
950 osthread()->print_on(st);
951 }
952 ThreadsSMRSupport::print_info_on(this, st);
953 st->print(" ");
954 debug_only(if (WizardMode) print_owned_locks_on(st);)
955}
956
957void Thread::print() const { print_on(tty); }
958
959// Thread::print_on_error() is called by fatal error handler. Don't use
960// any lock or allocate memory.
961void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
962 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
963
964 if (is_VM_thread()) { st->print("VMThread"); }
965 else if (is_GC_task_thread()) { st->print("GCTaskThread"); }
966 else if (is_Watcher_thread()) { st->print("WatcherThread"); }
967 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); }
968 else { st->print("Thread"); }
969
970 if (is_Named_thread()) {
971 st->print(" \"%s\"", name());
972 }
973
974 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
975 p2i(stack_end()), p2i(stack_base()));
976
977 if (osthread()) {
978 st->print(" [id=%d]", osthread()->thread_id());
979 }
980
981 ThreadsSMRSupport::print_info_on(this, st);
982}
983
984void Thread::print_value_on(outputStream* st) const {
985 if (is_Named_thread()) {
986 st->print(" \"%s\" ", name());
987 }
988 st->print(INTPTR_FORMAT, p2i(this)); // print address
989}
990
991#ifdef ASSERT
992void Thread::print_owned_locks_on(outputStream* st) const {
993 Monitor *cur = _owned_locks;
994 if (cur == NULL) {
995 st->print(" (no locks) ");
996 } else {
997 st->print_cr(" Locks owned:");
998 while (cur) {
999 cur->print_on(st);
1000 cur = cur->next();
1001 }
1002 }
1003}
1004
1005static int ref_use_count = 0;
1006
1007bool Thread::owns_locks_but_compiled_lock() const {
1008 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1009 if (cur != Compile_lock) return true;
1010 }
1011 return false;
1012}
1013
1014
1015#endif
1016
1017#ifndef PRODUCT
1018
1019// The flag: potential_vm_operation notifies if this particular safepoint state could potentially
1020// invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
1021// no locks which allow_vm_block's are held
1022void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
1023 // Check if current thread is allowed to block at a safepoint
1024 if (!(_allow_safepoint_count == 0)) {
1025 fatal("Possible safepoint reached by thread that does not allow it");
1026 }
1027 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
1028 fatal("LEAF method calling lock?");
1029 }
1030
1031#ifdef ASSERT
1032 if (potential_vm_operation && is_Java_thread()
1033 && !Universe::is_bootstrapping()) {
1034 // Make sure we do not hold any locks that the VM thread also uses.
1035 // This could potentially lead to deadlocks
1036 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
1037 // Threads_lock is special, since the safepoint synchronization will not start before this is
1038 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
1039 // since it is used to transfer control between JavaThreads and the VMThread
1040 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
1041 if ((cur->allow_vm_block() &&
1042 cur != Threads_lock &&
1043 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
1044 cur != VMOperationRequest_lock &&
1045 cur != VMOperationQueue_lock) ||
1046 cur->rank() == Mutex::special) {
1047 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name());
1048 }
1049 }
1050 }
1051
1052 if (GCALotAtAllSafepoints) {
1053 // We could enter a safepoint here and thus have a gc
1054 InterfaceSupport::check_gc_alot();
1055 }
1056#endif
1057}
1058#endif
1059
1060bool Thread::is_in_stack(address adr) const {
1061 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
1062 address end = os::current_stack_pointer();
1063 // Allow non Java threads to call this without stack_base
1064 if (_stack_base == NULL) return true;
1065 if (stack_base() >= adr && adr >= end) return true;
1066
1067 return false;
1068}
1069
1070bool Thread::is_in_usable_stack(address adr) const {
1071 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0;
1072 size_t usable_stack_size = _stack_size - stack_guard_size;
1073
1074 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
1075}
1076
1077
1078// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
1079// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
1080// used for compilation in the future. If that change is made, the need for these methods
1081// should be revisited, and they should be removed if possible.
1082
1083bool Thread::is_lock_owned(address adr) const {
1084 return on_local_stack(adr);
1085}
1086
1087bool Thread::set_as_starting_thread() {
1088 assert(_starting_thread == NULL, "already initialized: "
1089 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread));
1090 // NOTE: this must be called inside the main thread.
1091 DEBUG_ONLY(_starting_thread = this;)
1092 return os::create_main_thread((JavaThread*)this);
1093}
1094
1095static void initialize_class(Symbol* class_name, TRAPS) {
1096 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
1097 InstanceKlass::cast(klass)->initialize(CHECK);
1098}
1099
1100
1101// Creates the initial ThreadGroup
1102static Handle create_initial_thread_group(TRAPS) {
1103 Handle system_instance = JavaCalls::construct_new_instance(
1104 SystemDictionary::ThreadGroup_klass(),
1105 vmSymbols::void_method_signature(),
1106 CHECK_NH);
1107 Universe::set_system_thread_group(system_instance());
1108
1109 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
1110 Handle main_instance = JavaCalls::construct_new_instance(
1111 SystemDictionary::ThreadGroup_klass(),
1112 vmSymbols::threadgroup_string_void_signature(),
1113 system_instance,
1114 string,
1115 CHECK_NH);
1116 return main_instance;
1117}
1118
1119// Creates the initial Thread
1120static oop create_initial_thread(Handle thread_group, JavaThread* thread,
1121 TRAPS) {
1122 InstanceKlass* ik = SystemDictionary::Thread_klass();
1123 assert(ik->is_initialized(), "must be");
1124 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL);
1125
1126 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1127 // constructor calls Thread.current(), which must be set here for the
1128 // initial thread.
1129 java_lang_Thread::set_thread(thread_oop(), thread);
1130 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1131 thread->set_threadObj(thread_oop());
1132
1133 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
1134
1135 JavaValue result(T_VOID);
1136 JavaCalls::call_special(&result, thread_oop,
1137 ik,
1138 vmSymbols::object_initializer_name(),
1139 vmSymbols::threadgroup_string_void_signature(),
1140 thread_group,
1141 string,
1142 CHECK_NULL);
1143 return thread_oop();
1144}
1145
1146char java_runtime_name[128] = "";
1147char java_runtime_version[128] = "";
1148
1149// extract the JRE name from java.lang.VersionProps.java_runtime_name
1150static const char* get_java_runtime_name(TRAPS) {
1151 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1152 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1153 fieldDescriptor fd;
1154 bool found = k != NULL &&
1155 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1156 vmSymbols::string_signature(), &fd);
1157 if (found) {
1158 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1159 if (name_oop == NULL) {
1160 return NULL;
1161 }
1162 const char* name = java_lang_String::as_utf8_string(name_oop,
1163 java_runtime_name,
1164 sizeof(java_runtime_name));
1165 return name;
1166 } else {
1167 return NULL;
1168 }
1169}
1170
1171// extract the JRE version from java.lang.VersionProps.java_runtime_version
1172static const char* get_java_runtime_version(TRAPS) {
1173 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(),
1174 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1175 fieldDescriptor fd;
1176 bool found = k != NULL &&
1177 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1178 vmSymbols::string_signature(), &fd);
1179 if (found) {
1180 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1181 if (name_oop == NULL) {
1182 return NULL;
1183 }
1184 const char* name = java_lang_String::as_utf8_string(name_oop,
1185 java_runtime_version,
1186 sizeof(java_runtime_version));
1187 return name;
1188 } else {
1189 return NULL;
1190 }
1191}
1192
1193// General purpose hook into Java code, run once when the VM is initialized.
1194// The Java library method itself may be changed independently from the VM.
1195static void call_postVMInitHook(TRAPS) {
1196 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD);
1197 if (klass != NULL) {
1198 JavaValue result(T_VOID);
1199 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1200 vmSymbols::void_method_signature(),
1201 CHECK);
1202 }
1203}
1204
1205void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1206 bool daemon, TRAPS) {
1207 assert(thread_group.not_null(), "thread group should be specified");
1208 assert(threadObj() == NULL, "should only create Java thread object once");
1209
1210 InstanceKlass* ik = SystemDictionary::Thread_klass();
1211 assert(ik->is_initialized(), "must be");
1212 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK);
1213
1214 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon.
1215 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread
1216 // constructor calls Thread.current(), which must be set here.
1217 java_lang_Thread::set_thread(thread_oop(), this);
1218 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1219 set_threadObj(thread_oop());
1220
1221 JavaValue result(T_VOID);
1222 if (thread_name != NULL) {
1223 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1224 // Thread gets assigned specified name and null target
1225 JavaCalls::call_special(&result,
1226 thread_oop,
1227 ik,
1228 vmSymbols::object_initializer_name(),
1229 vmSymbols::threadgroup_string_void_signature(),
1230 thread_group,
1231 name,
1232 THREAD);
1233 } else {
1234 // Thread gets assigned name "Thread-nnn" and null target
1235 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1236 JavaCalls::call_special(&result,
1237 thread_oop,
1238 ik,
1239 vmSymbols::object_initializer_name(),
1240 vmSymbols::threadgroup_runnable_void_signature(),
1241 thread_group,
1242 Handle(),
1243 THREAD);
1244 }
1245
1246
1247 if (daemon) {
1248 java_lang_Thread::set_daemon(thread_oop());
1249 }
1250
1251 if (HAS_PENDING_EXCEPTION) {
1252 return;
1253 }
1254
1255 Klass* group = SystemDictionary::ThreadGroup_klass();
1256 Handle threadObj(THREAD, this->threadObj());
1257
1258 JavaCalls::call_special(&result,
1259 thread_group,
1260 group,
1261 vmSymbols::add_method_name(),
1262 vmSymbols::thread_void_signature(),
1263 threadObj, // Arg 1
1264 THREAD);
1265}
1266
1267// List of all NonJavaThreads and safe iteration over that list.
1268
1269class NonJavaThread::List {
1270public:
1271 NonJavaThread* volatile _head;
1272 SingleWriterSynchronizer _protect;
1273
1274 List() : _head(NULL), _protect() {}
1275};
1276
1277NonJavaThread::List NonJavaThread::_the_list;
1278
1279NonJavaThread::Iterator::Iterator() :
1280 _protect_enter(_the_list._protect.enter()),
1281 _current(OrderAccess::load_acquire(&_the_list._head))
1282{}
1283
1284NonJavaThread::Iterator::~Iterator() {
1285 _the_list._protect.exit(_protect_enter);
1286}
1287
1288void NonJavaThread::Iterator::step() {
1289 assert(!end(), "precondition");
1290 _current = OrderAccess::load_acquire(&_current->_next);
1291}
1292
1293NonJavaThread::NonJavaThread() : Thread(), _next(NULL) {
1294 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!");
1295}
1296
1297NonJavaThread::~NonJavaThread() { }
1298
1299void NonJavaThread::add_to_the_list() {
1300 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1301 // Initialize BarrierSet-related data before adding to list.
1302 BarrierSet::barrier_set()->on_thread_attach(this);
1303 OrderAccess::release_store(&_next, _the_list._head);
1304 OrderAccess::release_store(&_the_list._head, this);
1305}
1306
1307void NonJavaThread::remove_from_the_list() {
1308 {
1309 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag);
1310 // Cleanup BarrierSet-related data before removing from list.
1311 BarrierSet::barrier_set()->on_thread_detach(this);
1312 NonJavaThread* volatile* p = &_the_list._head;
1313 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) {
1314 if (t == this) {
1315 *p = _next;
1316 break;
1317 }
1318 }
1319 }
1320 // Wait for any in-progress iterators. Concurrent synchronize is not
1321 // allowed, so do it while holding a dedicated lock. Outside and distinct
1322 // from NJTList_lock in case an iteration attempts to lock it.
1323 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag);
1324 _the_list._protect.synchronize();
1325 _next = NULL; // Safe to drop the link now.
1326}
1327
1328void NonJavaThread::pre_run() {
1329 add_to_the_list();
1330
1331 // This is slightly odd in that NamedThread is a subclass, but
1332 // in fact name() is defined in Thread
1333 assert(this->name() != NULL, "thread name was not set before it was started");
1334 this->set_native_thread_name(this->name());
1335}
1336
1337void NonJavaThread::post_run() {
1338 JFR_ONLY(Jfr::on_thread_exit(this);)
1339 remove_from_the_list();
1340 // Ensure thread-local-storage is cleared before termination.
1341 Thread::clear_thread_current();
1342}
1343
1344// NamedThread -- non-JavaThread subclasses with multiple
1345// uniquely named instances should derive from this.
1346NamedThread::NamedThread() :
1347 NonJavaThread(),
1348 _name(NULL),
1349 _processed_thread(NULL),
1350 _gc_id(GCId::undefined())
1351{}
1352
1353NamedThread::~NamedThread() {
1354 if (_name != NULL) {
1355 FREE_C_HEAP_ARRAY(char, _name);
1356 _name = NULL;
1357 }
1358}
1359
1360void NamedThread::set_name(const char* format, ...) {
1361 guarantee(_name == NULL, "Only get to set name once.");
1362 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1363 guarantee(_name != NULL, "alloc failure");
1364 va_list ap;
1365 va_start(ap, format);
1366 jio_vsnprintf(_name, max_name_len, format, ap);
1367 va_end(ap);
1368}
1369
1370void NamedThread::print_on(outputStream* st) const {
1371 st->print("\"%s\" ", name());
1372 Thread::print_on(st);
1373 st->cr();
1374}
1375
1376
1377// ======= WatcherThread ========
1378
1379// The watcher thread exists to simulate timer interrupts. It should
1380// be replaced by an abstraction over whatever native support for
1381// timer interrupts exists on the platform.
1382
1383WatcherThread* WatcherThread::_watcher_thread = NULL;
1384bool WatcherThread::_startable = false;
1385volatile bool WatcherThread::_should_terminate = false;
1386
1387WatcherThread::WatcherThread() : NonJavaThread() {
1388 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1389 if (os::create_thread(this, os::watcher_thread)) {
1390 _watcher_thread = this;
1391
1392 // Set the watcher thread to the highest OS priority which should not be
1393 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1394 // is created. The only normal thread using this priority is the reference
1395 // handler thread, which runs for very short intervals only.
1396 // If the VMThread's priority is not lower than the WatcherThread profiling
1397 // will be inaccurate.
1398 os::set_priority(this, MaxPriority);
1399 if (!DisableStartThread) {
1400 os::start_thread(this);
1401 }
1402 }
1403}
1404
1405int WatcherThread::sleep() const {
1406 // The WatcherThread does not participate in the safepoint protocol
1407 // for the PeriodicTask_lock because it is not a JavaThread.
1408 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1409
1410 if (_should_terminate) {
1411 // check for termination before we do any housekeeping or wait
1412 return 0; // we did not sleep.
1413 }
1414
1415 // remaining will be zero if there are no tasks,
1416 // causing the WatcherThread to sleep until a task is
1417 // enrolled
1418 int remaining = PeriodicTask::time_to_wait();
1419 int time_slept = 0;
1420
1421 // we expect this to timeout - we only ever get unparked when
1422 // we should terminate or when a new task has been enrolled
1423 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1424
1425 jlong time_before_loop = os::javaTimeNanos();
1426
1427 while (true) {
1428 bool timedout = ml.wait(remaining);
1429 jlong now = os::javaTimeNanos();
1430
1431 if (remaining == 0) {
1432 // if we didn't have any tasks we could have waited for a long time
1433 // consider the time_slept zero and reset time_before_loop
1434 time_slept = 0;
1435 time_before_loop = now;
1436 } else {
1437 // need to recalculate since we might have new tasks in _tasks
1438 time_slept = (int) ((now - time_before_loop) / 1000000);
1439 }
1440
1441 // Change to task list or spurious wakeup of some kind
1442 if (timedout || _should_terminate) {
1443 break;
1444 }
1445
1446 remaining = PeriodicTask::time_to_wait();
1447 if (remaining == 0) {
1448 // Last task was just disenrolled so loop around and wait until
1449 // another task gets enrolled
1450 continue;
1451 }
1452
1453 remaining -= time_slept;
1454 if (remaining <= 0) {
1455 break;
1456 }
1457 }
1458
1459 return time_slept;
1460}
1461
1462void WatcherThread::run() {
1463 assert(this == watcher_thread(), "just checking");
1464
1465 this->set_active_handles(JNIHandleBlock::allocate_block());
1466 while (true) {
1467 assert(watcher_thread() == Thread::current(), "thread consistency check");
1468 assert(watcher_thread() == this, "thread consistency check");
1469
1470 // Calculate how long it'll be until the next PeriodicTask work
1471 // should be done, and sleep that amount of time.
1472 int time_waited = sleep();
1473
1474 if (VMError::is_error_reported()) {
1475 // A fatal error has happened, the error handler(VMError::report_and_die)
1476 // should abort JVM after creating an error log file. However in some
1477 // rare cases, the error handler itself might deadlock. Here periodically
1478 // check for error reporting timeouts, and if it happens, just proceed to
1479 // abort the VM.
1480
1481 // This code is in WatcherThread because WatcherThread wakes up
1482 // periodically so the fatal error handler doesn't need to do anything;
1483 // also because the WatcherThread is less likely to crash than other
1484 // threads.
1485
1486 for (;;) {
1487 // Note: we use naked sleep in this loop because we want to avoid using
1488 // any kind of VM infrastructure which may be broken at this point.
1489 if (VMError::check_timeout()) {
1490 // We hit error reporting timeout. Error reporting was interrupted and
1491 // will be wrapping things up now (closing files etc). Give it some more
1492 // time, then quit the VM.
1493 os::naked_short_sleep(200);
1494 // Print a message to stderr.
1495 fdStream err(defaultStream::output_fd());
1496 err.print_raw_cr("# [ timer expired, abort... ]");
1497 // skip atexit/vm_exit/vm_abort hooks
1498 os::die();
1499 }
1500
1501 // Wait a second, then recheck for timeout.
1502 os::naked_short_sleep(999);
1503 }
1504 }
1505
1506 if (_should_terminate) {
1507 // check for termination before posting the next tick
1508 break;
1509 }
1510
1511 PeriodicTask::real_time_tick(time_waited);
1512 }
1513
1514 // Signal that it is terminated
1515 {
1516 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1517 _watcher_thread = NULL;
1518 Terminator_lock->notify_all();
1519 }
1520}
1521
1522void WatcherThread::start() {
1523 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1524
1525 if (watcher_thread() == NULL && _startable) {
1526 _should_terminate = false;
1527 // Create the single instance of WatcherThread
1528 new WatcherThread();
1529 }
1530}
1531
1532void WatcherThread::make_startable() {
1533 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1534 _startable = true;
1535}
1536
1537void WatcherThread::stop() {
1538 {
1539 // Follow normal safepoint aware lock enter protocol since the
1540 // WatcherThread is stopped by another JavaThread.
1541 MutexLocker ml(PeriodicTask_lock);
1542 _should_terminate = true;
1543
1544 WatcherThread* watcher = watcher_thread();
1545 if (watcher != NULL) {
1546 // unpark the WatcherThread so it can see that it should terminate
1547 watcher->unpark();
1548 }
1549 }
1550
1551 MonitorLocker mu(Terminator_lock);
1552
1553 while (watcher_thread() != NULL) {
1554 // This wait should make safepoint checks, wait without a timeout,
1555 // and wait as a suspend-equivalent condition.
1556 mu.wait(0, Mutex::_as_suspend_equivalent_flag);
1557 }
1558}
1559
1560void WatcherThread::unpark() {
1561 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1562 PeriodicTask_lock->notify();
1563}
1564
1565void WatcherThread::print_on(outputStream* st) const {
1566 st->print("\"%s\" ", name());
1567 Thread::print_on(st);
1568 st->cr();
1569}
1570
1571// ======= JavaThread ========
1572
1573#if INCLUDE_JVMCI
1574
1575jlong* JavaThread::_jvmci_old_thread_counters;
1576
1577bool jvmci_counters_include(JavaThread* thread) {
1578 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
1579}
1580
1581void JavaThread::collect_counters(jlong* array, int length) {
1582 assert(length == JVMCICounterSize, "wrong value");
1583 for (int i = 0; i < length; i++) {
1584 array[i] = _jvmci_old_thread_counters[i];
1585 }
1586 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1587 if (jvmci_counters_include(tp)) {
1588 for (int i = 0; i < length; i++) {
1589 array[i] += tp->_jvmci_counters[i];
1590 }
1591 }
1592 }
1593}
1594
1595// Attempt to enlarge the array for per thread counters.
1596jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) {
1597 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI);
1598 if (new_counters == NULL) {
1599 return NULL;
1600 }
1601 if (old_counters == NULL) {
1602 old_counters = new_counters;
1603 memset(old_counters, 0, sizeof(jlong) * new_size);
1604 } else {
1605 for (int i = 0; i < MIN2((int) current_size, new_size); i++) {
1606 new_counters[i] = old_counters[i];
1607 }
1608 if (new_size > current_size) {
1609 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size));
1610 }
1611 FREE_C_HEAP_ARRAY(jlong, old_counters);
1612 }
1613 return new_counters;
1614}
1615
1616// Attempt to enlarge the array for per thread counters.
1617bool JavaThread::resize_counters(int current_size, int new_size) {
1618 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size);
1619 if (new_counters == NULL) {
1620 return false;
1621 } else {
1622 _jvmci_counters = new_counters;
1623 return true;
1624 }
1625}
1626
1627class VM_JVMCIResizeCounters : public VM_Operation {
1628 private:
1629 int _new_size;
1630 bool _failed;
1631
1632 public:
1633 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { }
1634 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; }
1635 bool allow_nested_vm_operations() const { return true; }
1636 void doit() {
1637 // Resize the old thread counters array
1638 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size);
1639 if (new_counters == NULL) {
1640 _failed = true;
1641 return;
1642 } else {
1643 JavaThread::_jvmci_old_thread_counters = new_counters;
1644 }
1645
1646 // Now resize each threads array
1647 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) {
1648 if (!tp->resize_counters(JVMCICounterSize, _new_size)) {
1649 _failed = true;
1650 break;
1651 }
1652 }
1653 if (!_failed) {
1654 JVMCICounterSize = _new_size;
1655 }
1656 }
1657
1658 bool failed() { return _failed; }
1659};
1660
1661bool JavaThread::resize_all_jvmci_counters(int new_size) {
1662 VM_JVMCIResizeCounters op(new_size);
1663 VMThread::execute(&op);
1664 return !op.failed();
1665}
1666
1667#endif // INCLUDE_JVMCI
1668
1669// A JavaThread is a normal Java thread
1670
1671void JavaThread::initialize() {
1672 // Initialize fields
1673
1674 set_saved_exception_pc(NULL);
1675 set_threadObj(NULL);
1676 _anchor.clear();
1677 set_entry_point(NULL);
1678 set_jni_functions(jni_functions());
1679 set_callee_target(NULL);
1680 set_vm_result(NULL);
1681 set_vm_result_2(NULL);
1682 set_vframe_array_head(NULL);
1683 set_vframe_array_last(NULL);
1684 set_deferred_locals(NULL);
1685 set_deopt_mark(NULL);
1686 set_deopt_compiled_method(NULL);
1687 clear_must_deopt_id();
1688 set_monitor_chunks(NULL);
1689 _on_thread_list = false;
1690 set_thread_state(_thread_new);
1691 _terminated = _not_terminated;
1692 _array_for_gc = NULL;
1693 _suspend_equivalent = false;
1694 _in_deopt_handler = 0;
1695 _doing_unsafe_access = false;
1696 _stack_guard_state = stack_guard_unused;
1697#if INCLUDE_JVMCI
1698 _pending_monitorenter = false;
1699 _pending_deoptimization = -1;
1700 _pending_failed_speculation = 0;
1701 _pending_transfer_to_interpreter = false;
1702 _in_retryable_allocation = false;
1703 _jvmci._alternate_call_target = NULL;
1704 assert(_jvmci._implicit_exception_pc == NULL, "must be");
1705 _jvmci_counters = NULL;
1706 if (JVMCICounterSize > 0) {
1707 resize_counters(0, (int) JVMCICounterSize);
1708 }
1709#endif // INCLUDE_JVMCI
1710 _reserved_stack_activation = NULL; // stack base not known yet
1711 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1712 _exception_pc = 0;
1713 _exception_handler_pc = 0;
1714 _is_method_handle_return = 0;
1715 _jvmti_thread_state= NULL;
1716 _should_post_on_exceptions_flag = JNI_FALSE;
1717 _interp_only_mode = 0;
1718 _special_runtime_exit_condition = _no_async_condition;
1719 _pending_async_exception = NULL;
1720 _thread_stat = NULL;
1721 _thread_stat = new ThreadStatistics();
1722 _blocked_on_compilation = false;
1723 _jni_active_critical = 0;
1724 _pending_jni_exception_check_fn = NULL;
1725 _do_not_unlock_if_synchronized = false;
1726 _cached_monitor_info = NULL;
1727 _parker = Parker::Allocate(this);
1728
1729#ifndef PRODUCT
1730 _jmp_ring_index = 0;
1731 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1732 record_jump(NULL, NULL, NULL, 0);
1733 }
1734#endif // PRODUCT
1735
1736 // Setup safepoint state info for this thread
1737 ThreadSafepointState::create(this);
1738
1739 debug_only(_java_call_counter = 0);
1740
1741 // JVMTI PopFrame support
1742 _popframe_condition = popframe_inactive;
1743 _popframe_preserved_args = NULL;
1744 _popframe_preserved_args_size = 0;
1745 _frames_to_pop_failed_realloc = 0;
1746
1747 if (SafepointMechanism::uses_thread_local_poll()) {
1748 SafepointMechanism::initialize_header(this);
1749 }
1750
1751 _class_to_be_initialized = NULL;
1752
1753 pd_initialize();
1754}
1755
1756JavaThread::JavaThread(bool is_attaching_via_jni) :
1757 Thread() {
1758 initialize();
1759 if (is_attaching_via_jni) {
1760 _jni_attach_state = _attaching_via_jni;
1761 } else {
1762 _jni_attach_state = _not_attaching_via_jni;
1763 }
1764 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1765}
1766
1767bool JavaThread::reguard_stack(address cur_sp) {
1768 if (_stack_guard_state != stack_guard_yellow_reserved_disabled
1769 && _stack_guard_state != stack_guard_reserved_disabled) {
1770 return true; // Stack already guarded or guard pages not needed.
1771 }
1772
1773 if (register_stack_overflow()) {
1774 // For those architectures which have separate register and
1775 // memory stacks, we must check the register stack to see if
1776 // it has overflowed.
1777 return false;
1778 }
1779
1780 // Java code never executes within the yellow zone: the latter is only
1781 // there to provoke an exception during stack banging. If java code
1782 // is executing there, either StackShadowPages should be larger, or
1783 // some exception code in c1, c2 or the interpreter isn't unwinding
1784 // when it should.
1785 guarantee(cur_sp > stack_reserved_zone_base(),
1786 "not enough space to reguard - increase StackShadowPages");
1787 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) {
1788 enable_stack_yellow_reserved_zone();
1789 if (reserved_stack_activation() != stack_base()) {
1790 set_reserved_stack_activation(stack_base());
1791 }
1792 } else if (_stack_guard_state == stack_guard_reserved_disabled) {
1793 set_reserved_stack_activation(stack_base());
1794 enable_stack_reserved_zone();
1795 }
1796 return true;
1797}
1798
1799bool JavaThread::reguard_stack(void) {
1800 return reguard_stack(os::current_stack_pointer());
1801}
1802
1803
1804void JavaThread::block_if_vm_exited() {
1805 if (_terminated == _vm_exited) {
1806 // _vm_exited is set at safepoint, and Threads_lock is never released
1807 // we will block here forever
1808 Threads_lock->lock_without_safepoint_check();
1809 ShouldNotReachHere();
1810 }
1811}
1812
1813
1814// Remove this ifdef when C1 is ported to the compiler interface.
1815static void compiler_thread_entry(JavaThread* thread, TRAPS);
1816static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1817
1818JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1819 Thread() {
1820 initialize();
1821 _jni_attach_state = _not_attaching_via_jni;
1822 set_entry_point(entry_point);
1823 // Create the native thread itself.
1824 // %note runtime_23
1825 os::ThreadType thr_type = os::java_thread;
1826 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1827 os::java_thread;
1828 os::create_thread(this, thr_type, stack_sz);
1829 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1830 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1831 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1832 // the exception consists of creating the exception object & initializing it, initialization
1833 // will leave the VM via a JavaCall and then all locks must be unlocked).
1834 //
1835 // The thread is still suspended when we reach here. Thread must be explicit started
1836 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1837 // by calling Threads:add. The reason why this is not done here, is because the thread
1838 // object must be fully initialized (take a look at JVM_Start)
1839}
1840
1841JavaThread::~JavaThread() {
1842
1843 // JSR166 -- return the parker to the free list
1844 Parker::Release(_parker);
1845 _parker = NULL;
1846
1847 // Free any remaining previous UnrollBlock
1848 vframeArray* old_array = vframe_array_last();
1849
1850 if (old_array != NULL) {
1851 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1852 old_array->set_unroll_block(NULL);
1853 delete old_info;
1854 delete old_array;
1855 }
1856
1857 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1858 if (deferred != NULL) {
1859 // This can only happen if thread is destroyed before deoptimization occurs.
1860 assert(deferred->length() != 0, "empty array!");
1861 do {
1862 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1863 deferred->remove_at(0);
1864 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1865 delete dlv;
1866 } while (deferred->length() != 0);
1867 delete deferred;
1868 }
1869
1870 // All Java related clean up happens in exit
1871 ThreadSafepointState::destroy(this);
1872 if (_thread_stat != NULL) delete _thread_stat;
1873
1874#if INCLUDE_JVMCI
1875 if (JVMCICounterSize > 0) {
1876 if (jvmci_counters_include(this)) {
1877 for (int i = 0; i < JVMCICounterSize; i++) {
1878 _jvmci_old_thread_counters[i] += _jvmci_counters[i];
1879 }
1880 }
1881 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters);
1882 }
1883#endif // INCLUDE_JVMCI
1884}
1885
1886
1887// First JavaThread specific code executed by a new Java thread.
1888void JavaThread::pre_run() {
1889 // empty - see comments in run()
1890}
1891
1892// The main routine called by a new Java thread. This isn't overridden
1893// by subclasses, instead different subclasses define a different "entry_point"
1894// which defines the actual logic for that kind of thread.
1895void JavaThread::run() {
1896 // initialize thread-local alloc buffer related fields
1897 this->initialize_tlab();
1898
1899 // Used to test validity of stack trace backs.
1900 // This can't be moved into pre_run() else we invalidate
1901 // the requirement that thread_main_inner is lower on
1902 // the stack. Consequently all the initialization logic
1903 // stays here in run() rather than pre_run().
1904 this->record_base_of_stack_pointer();
1905
1906 this->create_stack_guard_pages();
1907
1908 this->cache_global_variables();
1909
1910 // Thread is now sufficiently initialized to be handled by the safepoint code as being
1911 // in the VM. Change thread state from _thread_new to _thread_in_vm
1912 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm);
1913 // Before a thread is on the threads list it is always safe, so after leaving the
1914 // _thread_new we should emit a instruction barrier. The distance to modified code
1915 // from here is probably far enough, but this is consistent and safe.
1916 OrderAccess::cross_modify_fence();
1917
1918 assert(JavaThread::current() == this, "sanity check");
1919 assert(!Thread::current()->owns_locks(), "sanity check");
1920
1921 DTRACE_THREAD_PROBE(start, this);
1922
1923 // This operation might block. We call that after all safepoint checks for a new thread has
1924 // been completed.
1925 this->set_active_handles(JNIHandleBlock::allocate_block());
1926
1927 if (JvmtiExport::should_post_thread_life()) {
1928 JvmtiExport::post_thread_start(this);
1929
1930 }
1931
1932 // We call another function to do the rest so we are sure that the stack addresses used
1933 // from there will be lower than the stack base just computed.
1934 thread_main_inner();
1935}
1936
1937void JavaThread::thread_main_inner() {
1938 assert(JavaThread::current() == this, "sanity check");
1939 assert(this->threadObj() != NULL, "just checking");
1940
1941 // Execute thread entry point unless this thread has a pending exception
1942 // or has been stopped before starting.
1943 // Note: Due to JVM_StopThread we can have pending exceptions already!
1944 if (!this->has_pending_exception() &&
1945 !java_lang_Thread::is_stillborn(this->threadObj())) {
1946 {
1947 ResourceMark rm(this);
1948 this->set_native_thread_name(this->get_thread_name());
1949 }
1950 HandleMark hm(this);
1951 this->entry_point()(this, this);
1952 }
1953
1954 DTRACE_THREAD_PROBE(stop, this);
1955
1956 // Cleanup is handled in post_run()
1957}
1958
1959// Shared teardown for all JavaThreads
1960void JavaThread::post_run() {
1961 this->exit(false);
1962 // Defer deletion to here to ensure 'this' is still referenceable in call_run
1963 // for any shared tear-down.
1964 this->smr_delete();
1965}
1966
1967static void ensure_join(JavaThread* thread) {
1968 // We do not need to grab the Threads_lock, since we are operating on ourself.
1969 Handle threadObj(thread, thread->threadObj());
1970 assert(threadObj.not_null(), "java thread object must exist");
1971 ObjectLocker lock(threadObj, thread);
1972 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1973 thread->clear_pending_exception();
1974 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1975 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1976 // Clear the native thread instance - this makes isAlive return false and allows the join()
1977 // to complete once we've done the notify_all below
1978 java_lang_Thread::set_thread(threadObj(), NULL);
1979 lock.notify_all(thread);
1980 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1981 thread->clear_pending_exception();
1982}
1983
1984static bool is_daemon(oop threadObj) {
1985 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj));
1986}
1987
1988// For any new cleanup additions, please check to see if they need to be applied to
1989// cleanup_failed_attach_current_thread as well.
1990void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1991 assert(this == JavaThread::current(), "thread consistency check");
1992
1993 elapsedTimer _timer_exit_phase1;
1994 elapsedTimer _timer_exit_phase2;
1995 elapsedTimer _timer_exit_phase3;
1996 elapsedTimer _timer_exit_phase4;
1997
1998 if (log_is_enabled(Debug, os, thread, timer)) {
1999 _timer_exit_phase1.start();
2000 }
2001
2002 HandleMark hm(this);
2003 Handle uncaught_exception(this, this->pending_exception());
2004 this->clear_pending_exception();
2005 Handle threadObj(this, this->threadObj());
2006 assert(threadObj.not_null(), "Java thread object should be created");
2007
2008 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
2009 {
2010 EXCEPTION_MARK;
2011
2012 CLEAR_PENDING_EXCEPTION;
2013 }
2014 if (!destroy_vm) {
2015 if (uncaught_exception.not_null()) {
2016 EXCEPTION_MARK;
2017 // Call method Thread.dispatchUncaughtException().
2018 Klass* thread_klass = SystemDictionary::Thread_klass();
2019 JavaValue result(T_VOID);
2020 JavaCalls::call_virtual(&result,
2021 threadObj, thread_klass,
2022 vmSymbols::dispatchUncaughtException_name(),
2023 vmSymbols::throwable_void_signature(),
2024 uncaught_exception,
2025 THREAD);
2026 if (HAS_PENDING_EXCEPTION) {
2027 ResourceMark rm(this);
2028 jio_fprintf(defaultStream::error_stream(),
2029 "\nException: %s thrown from the UncaughtExceptionHandler"
2030 " in thread \"%s\"\n",
2031 pending_exception()->klass()->external_name(),
2032 get_thread_name());
2033 CLEAR_PENDING_EXCEPTION;
2034 }
2035 }
2036 JFR_ONLY(Jfr::on_java_thread_dismantle(this);)
2037
2038 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
2039 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
2040 // is deprecated anyhow.
2041 if (!is_Compiler_thread()) {
2042 int count = 3;
2043 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
2044 EXCEPTION_MARK;
2045 JavaValue result(T_VOID);
2046 Klass* thread_klass = SystemDictionary::Thread_klass();
2047 JavaCalls::call_virtual(&result,
2048 threadObj, thread_klass,
2049 vmSymbols::exit_method_name(),
2050 vmSymbols::void_method_signature(),
2051 THREAD);
2052 CLEAR_PENDING_EXCEPTION;
2053 }
2054 }
2055 // notify JVMTI
2056 if (JvmtiExport::should_post_thread_life()) {
2057 JvmtiExport::post_thread_end(this);
2058 }
2059
2060 // We have notified the agents that we are exiting, before we go on,
2061 // we must check for a pending external suspend request and honor it
2062 // in order to not surprise the thread that made the suspend request.
2063 while (true) {
2064 {
2065 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2066 if (!is_external_suspend()) {
2067 set_terminated(_thread_exiting);
2068 ThreadService::current_thread_exiting(this, is_daemon(threadObj()));
2069 break;
2070 }
2071 // Implied else:
2072 // Things get a little tricky here. We have a pending external
2073 // suspend request, but we are holding the SR_lock so we
2074 // can't just self-suspend. So we temporarily drop the lock
2075 // and then self-suspend.
2076 }
2077
2078 ThreadBlockInVM tbivm(this);
2079 java_suspend_self();
2080
2081 // We're done with this suspend request, but we have to loop around
2082 // and check again. Eventually we will get SR_lock without a pending
2083 // external suspend request and will be able to mark ourselves as
2084 // exiting.
2085 }
2086 // no more external suspends are allowed at this point
2087 } else {
2088 assert(!is_terminated() && !is_exiting(), "must not be exiting");
2089 // before_exit() has already posted JVMTI THREAD_END events
2090 }
2091
2092 if (log_is_enabled(Debug, os, thread, timer)) {
2093 _timer_exit_phase1.stop();
2094 _timer_exit_phase2.start();
2095 }
2096
2097 // Capture daemon status before the thread is marked as terminated.
2098 bool daemon = is_daemon(threadObj());
2099
2100 // Notify waiters on thread object. This has to be done after exit() is called
2101 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
2102 // group should have the destroyed bit set before waiters are notified).
2103 ensure_join(this);
2104 assert(!this->has_pending_exception(), "ensure_join should have cleared");
2105
2106 if (log_is_enabled(Debug, os, thread, timer)) {
2107 _timer_exit_phase2.stop();
2108 _timer_exit_phase3.start();
2109 }
2110 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
2111 // held by this thread must be released. The spec does not distinguish
2112 // between JNI-acquired and regular Java monitors. We can only see
2113 // regular Java monitors here if monitor enter-exit matching is broken.
2114 //
2115 // ensure_join() ignores IllegalThreadStateExceptions, and so does
2116 // ObjectSynchronizer::release_monitors_owned_by_thread().
2117 if (exit_type == jni_detach) {
2118 // Sanity check even though JNI DetachCurrentThread() would have
2119 // returned JNI_ERR if there was a Java frame. JavaThread exit
2120 // should be done executing Java code by the time we get here.
2121 assert(!this->has_last_Java_frame(),
2122 "should not have a Java frame when detaching or exiting");
2123 ObjectSynchronizer::release_monitors_owned_by_thread(this);
2124 assert(!this->has_pending_exception(), "release_monitors should have cleared");
2125 }
2126
2127 // These things needs to be done while we are still a Java Thread. Make sure that thread
2128 // is in a consistent state, in case GC happens
2129 JFR_ONLY(Jfr::on_thread_exit(this);)
2130
2131 if (active_handles() != NULL) {
2132 JNIHandleBlock* block = active_handles();
2133 set_active_handles(NULL);
2134 JNIHandleBlock::release_block(block);
2135 }
2136
2137 if (free_handle_block() != NULL) {
2138 JNIHandleBlock* block = free_handle_block();
2139 set_free_handle_block(NULL);
2140 JNIHandleBlock::release_block(block);
2141 }
2142
2143 // These have to be removed while this is still a valid thread.
2144 remove_stack_guard_pages();
2145
2146 if (UseTLAB) {
2147 tlab().retire();
2148 }
2149
2150 if (JvmtiEnv::environments_might_exist()) {
2151 JvmtiExport::cleanup_thread(this);
2152 }
2153
2154 // We must flush any deferred card marks and other various GC barrier
2155 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer)
2156 // before removing a thread from the list of active threads.
2157 BarrierSet::barrier_set()->on_thread_detach(this);
2158
2159 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
2160 exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
2161 os::current_thread_id());
2162
2163 if (log_is_enabled(Debug, os, thread, timer)) {
2164 _timer_exit_phase3.stop();
2165 _timer_exit_phase4.start();
2166 }
2167 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
2168 Threads::remove(this, daemon);
2169
2170 if (log_is_enabled(Debug, os, thread, timer)) {
2171 _timer_exit_phase4.stop();
2172 ResourceMark rm(this);
2173 log_debug(os, thread, timer)("name='%s'"
2174 ", exit-phase1=" JLONG_FORMAT
2175 ", exit-phase2=" JLONG_FORMAT
2176 ", exit-phase3=" JLONG_FORMAT
2177 ", exit-phase4=" JLONG_FORMAT,
2178 get_thread_name(),
2179 _timer_exit_phase1.milliseconds(),
2180 _timer_exit_phase2.milliseconds(),
2181 _timer_exit_phase3.milliseconds(),
2182 _timer_exit_phase4.milliseconds());
2183 }
2184}
2185
2186void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) {
2187 if (active_handles() != NULL) {
2188 JNIHandleBlock* block = active_handles();
2189 set_active_handles(NULL);
2190 JNIHandleBlock::release_block(block);
2191 }
2192
2193 if (free_handle_block() != NULL) {
2194 JNIHandleBlock* block = free_handle_block();
2195 set_free_handle_block(NULL);
2196 JNIHandleBlock::release_block(block);
2197 }
2198
2199 // These have to be removed while this is still a valid thread.
2200 remove_stack_guard_pages();
2201
2202 if (UseTLAB) {
2203 tlab().retire();
2204 }
2205
2206 BarrierSet::barrier_set()->on_thread_detach(this);
2207
2208 Threads::remove(this, is_daemon);
2209 this->smr_delete();
2210}
2211
2212JavaThread* JavaThread::active() {
2213 Thread* thread = Thread::current();
2214 if (thread->is_Java_thread()) {
2215 return (JavaThread*) thread;
2216 } else {
2217 assert(thread->is_VM_thread(), "this must be a vm thread");
2218 VM_Operation* op = ((VMThread*) thread)->vm_operation();
2219 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
2220 assert(ret->is_Java_thread(), "must be a Java thread");
2221 return ret;
2222 }
2223}
2224
2225bool JavaThread::is_lock_owned(address adr) const {
2226 if (Thread::is_lock_owned(adr)) return true;
2227
2228 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2229 if (chunk->contains(adr)) return true;
2230 }
2231
2232 return false;
2233}
2234
2235
2236void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
2237 chunk->set_next(monitor_chunks());
2238 set_monitor_chunks(chunk);
2239}
2240
2241void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
2242 guarantee(monitor_chunks() != NULL, "must be non empty");
2243 if (monitor_chunks() == chunk) {
2244 set_monitor_chunks(chunk->next());
2245 } else {
2246 MonitorChunk* prev = monitor_chunks();
2247 while (prev->next() != chunk) prev = prev->next();
2248 prev->set_next(chunk->next());
2249 }
2250}
2251
2252// JVM support.
2253
2254// Note: this function shouldn't block if it's called in
2255// _thread_in_native_trans state (such as from
2256// check_special_condition_for_native_trans()).
2257void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
2258
2259 if (has_last_Java_frame() && has_async_condition()) {
2260 // If we are at a polling page safepoint (not a poll return)
2261 // then we must defer async exception because live registers
2262 // will be clobbered by the exception path. Poll return is
2263 // ok because the call we a returning from already collides
2264 // with exception handling registers and so there is no issue.
2265 // (The exception handling path kills call result registers but
2266 // this is ok since the exception kills the result anyway).
2267
2268 if (is_at_poll_safepoint()) {
2269 // if the code we are returning to has deoptimized we must defer
2270 // the exception otherwise live registers get clobbered on the
2271 // exception path before deoptimization is able to retrieve them.
2272 //
2273 RegisterMap map(this, false);
2274 frame caller_fr = last_frame().sender(&map);
2275 assert(caller_fr.is_compiled_frame(), "what?");
2276 if (caller_fr.is_deoptimized_frame()) {
2277 log_info(exceptions)("deferred async exception at compiled safepoint");
2278 return;
2279 }
2280 }
2281 }
2282
2283 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2284 if (condition == _no_async_condition) {
2285 // Conditions have changed since has_special_runtime_exit_condition()
2286 // was called:
2287 // - if we were here only because of an external suspend request,
2288 // then that was taken care of above (or cancelled) so we are done
2289 // - if we were here because of another async request, then it has
2290 // been cleared between the has_special_runtime_exit_condition()
2291 // and now so again we are done
2292 return;
2293 }
2294
2295 // Check for pending async. exception
2296 if (_pending_async_exception != NULL) {
2297 // Only overwrite an already pending exception, if it is not a threadDeath.
2298 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2299
2300 // We cannot call Exceptions::_throw(...) here because we cannot block
2301 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2302
2303 LogTarget(Info, exceptions) lt;
2304 if (lt.is_enabled()) {
2305 ResourceMark rm;
2306 LogStream ls(lt);
2307 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this));
2308 if (has_last_Java_frame()) {
2309 frame f = last_frame();
2310 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp()));
2311 }
2312 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name());
2313 }
2314 _pending_async_exception = NULL;
2315 clear_has_async_exception();
2316 }
2317 }
2318
2319 if (check_unsafe_error &&
2320 condition == _async_unsafe_access_error && !has_pending_exception()) {
2321 condition = _no_async_condition; // done
2322 switch (thread_state()) {
2323 case _thread_in_vm: {
2324 JavaThread* THREAD = this;
2325 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2326 }
2327 case _thread_in_native: {
2328 ThreadInVMfromNative tiv(this);
2329 JavaThread* THREAD = this;
2330 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2331 }
2332 case _thread_in_Java: {
2333 ThreadInVMfromJava tiv(this);
2334 JavaThread* THREAD = this;
2335 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2336 }
2337 default:
2338 ShouldNotReachHere();
2339 }
2340 }
2341
2342 assert(condition == _no_async_condition || has_pending_exception() ||
2343 (!check_unsafe_error && condition == _async_unsafe_access_error),
2344 "must have handled the async condition, if no exception");
2345}
2346
2347void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2348 //
2349 // Check for pending external suspend.
2350 // If JNIEnv proxies are allowed, don't self-suspend if the target
2351 // thread is not the current thread. In older versions of jdbx, jdbx
2352 // threads could call into the VM with another thread's JNIEnv so we
2353 // can be here operating on behalf of a suspended thread (4432884).
2354 bool do_self_suspend = is_external_suspend_with_lock();
2355 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2356 frame_anchor()->make_walkable(this);
2357 java_suspend_self_with_safepoint_check();
2358 }
2359
2360 // We might be here for reasons in addition to the self-suspend request
2361 // so check for other async requests.
2362 if (check_asyncs) {
2363 check_and_handle_async_exceptions();
2364 }
2365
2366 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);)
2367}
2368
2369void JavaThread::send_thread_stop(oop java_throwable) {
2370 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2371 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2372 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2373
2374 // Do not throw asynchronous exceptions against the compiler thread
2375 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2376 if (!can_call_java()) return;
2377
2378 {
2379 // Actually throw the Throwable against the target Thread - however
2380 // only if there is no thread death exception installed already.
2381 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2382 // If the topmost frame is a runtime stub, then we are calling into
2383 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2384 // must deoptimize the caller before continuing, as the compiled exception handler table
2385 // may not be valid
2386 if (has_last_Java_frame()) {
2387 frame f = last_frame();
2388 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2389 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2390 RegisterMap reg_map(this, UseBiasedLocking);
2391 frame compiled_frame = f.sender(&reg_map);
2392 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2393 Deoptimization::deoptimize(this, compiled_frame, &reg_map);
2394 }
2395 }
2396 }
2397
2398 // Set async. pending exception in thread.
2399 set_pending_async_exception(java_throwable);
2400
2401 if (log_is_enabled(Info, exceptions)) {
2402 ResourceMark rm;
2403 log_info(exceptions)("Pending Async. exception installed of type: %s",
2404 InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2405 }
2406 // for AbortVMOnException flag
2407 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name());
2408 }
2409 }
2410
2411
2412 // Interrupt thread so it will wake up from a potential wait()
2413 Thread::interrupt(this);
2414}
2415
2416// External suspension mechanism.
2417//
2418// Tell the VM to suspend a thread when ever it knows that it does not hold on
2419// to any VM_locks and it is at a transition
2420// Self-suspension will happen on the transition out of the vm.
2421// Catch "this" coming in from JNIEnv pointers when the thread has been freed
2422//
2423// Guarantees on return:
2424// + Target thread will not execute any new bytecode (that's why we need to
2425// force a safepoint)
2426// + Target thread will not enter any new monitors
2427//
2428void JavaThread::java_suspend() {
2429 ThreadsListHandle tlh;
2430 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
2431 return;
2432 }
2433
2434 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2435 if (!is_external_suspend()) {
2436 // a racing resume has cancelled us; bail out now
2437 return;
2438 }
2439
2440 // suspend is done
2441 uint32_t debug_bits = 0;
2442 // Warning: is_ext_suspend_completed() may temporarily drop the
2443 // SR_lock to allow the thread to reach a stable thread state if
2444 // it is currently in a transient thread state.
2445 if (is_ext_suspend_completed(false /* !called_by_wait */,
2446 SuspendRetryDelay, &debug_bits)) {
2447 return;
2448 }
2449 }
2450
2451 if (Thread::current() == this) {
2452 // Safely self-suspend.
2453 // If we don't do this explicitly it will implicitly happen
2454 // before we transition back to Java, and on some other thread-state
2455 // transition paths, but not as we exit a JVM TI SuspendThread call.
2456 // As SuspendThread(current) must not return (until resumed) we must
2457 // self-suspend here.
2458 ThreadBlockInVM tbivm(this);
2459 java_suspend_self();
2460 } else {
2461 VM_ThreadSuspend vm_suspend;
2462 VMThread::execute(&vm_suspend);
2463 }
2464}
2465
2466// Part II of external suspension.
2467// A JavaThread self suspends when it detects a pending external suspend
2468// request. This is usually on transitions. It is also done in places
2469// where continuing to the next transition would surprise the caller,
2470// e.g., monitor entry.
2471//
2472// Returns the number of times that the thread self-suspended.
2473//
2474// Note: DO NOT call java_suspend_self() when you just want to block current
2475// thread. java_suspend_self() is the second stage of cooperative
2476// suspension for external suspend requests and should only be used
2477// to complete an external suspend request.
2478//
2479int JavaThread::java_suspend_self() {
2480 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()");
2481 int ret = 0;
2482
2483 // we are in the process of exiting so don't suspend
2484 if (is_exiting()) {
2485 clear_external_suspend();
2486 return ret;
2487 }
2488
2489 assert(_anchor.walkable() ||
2490 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2491 "must have walkable stack");
2492
2493 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2494
2495 assert(!this->is_ext_suspended(),
2496 "a thread trying to self-suspend should not already be suspended");
2497
2498 if (this->is_suspend_equivalent()) {
2499 // If we are self-suspending as a result of the lifting of a
2500 // suspend equivalent condition, then the suspend_equivalent
2501 // flag is not cleared until we set the ext_suspended flag so
2502 // that wait_for_ext_suspend_completion() returns consistent
2503 // results.
2504 this->clear_suspend_equivalent();
2505 }
2506
2507 // A racing resume may have cancelled us before we grabbed SR_lock
2508 // above. Or another external suspend request could be waiting for us
2509 // by the time we return from SR_lock()->wait(). The thread
2510 // that requested the suspension may already be trying to walk our
2511 // stack and if we return now, we can change the stack out from under
2512 // it. This would be a "bad thing (TM)" and cause the stack walker
2513 // to crash. We stay self-suspended until there are no more pending
2514 // external suspend requests.
2515 while (is_external_suspend()) {
2516 ret++;
2517 this->set_ext_suspended();
2518
2519 // _ext_suspended flag is cleared by java_resume()
2520 while (is_ext_suspended()) {
2521 ml.wait();
2522 }
2523 }
2524 return ret;
2525}
2526
2527// Helper routine to set up the correct thread state before calling java_suspend_self.
2528// This is called when regular thread-state transition helpers can't be used because
2529// we can be in various states, in particular _thread_in_native_trans.
2530// Because this thread is external suspended the safepoint code will count it as at
2531// a safepoint, regardless of what its actual current thread-state is. But
2532// is_ext_suspend_completed() may be waiting to see a thread transition from
2533// _thread_in_native_trans to _thread_blocked. So we set the thread state directly
2534// to _thread_blocked. The problem with setting thread state directly is that a
2535// safepoint could happen just after java_suspend_self() returns after being resumed,
2536// and the VM thread will see the _thread_blocked state. So we must check for a safepoint
2537// after restoring the state to make sure we won't leave while a safepoint is in progress.
2538// However, not all initial-states are allowed when performing a safepoint check, as we
2539// should never be blocking at a safepoint whilst in those states. Of these 'bad' states
2540// only _thread_in_native is possible when executing this code (based on our two callers).
2541// A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter
2542// whether the VMThread sees the _thread_blocked state, or the _thread_in_native state,
2543// and so we don't need the explicit safepoint check.
2544
2545void JavaThread::java_suspend_self_with_safepoint_check() {
2546 assert(this == Thread::current(), "invariant");
2547 JavaThreadState state = thread_state();
2548 set_thread_state(_thread_blocked);
2549 java_suspend_self();
2550 set_thread_state_fence(state);
2551 // Since we are not using a regular thread-state transition helper here,
2552 // we must manually emit the instruction barrier after leaving a safe state.
2553 OrderAccess::cross_modify_fence();
2554 if (state != _thread_in_native) {
2555 SafepointMechanism::block_if_requested(this);
2556 }
2557}
2558
2559#ifdef ASSERT
2560// Verify the JavaThread has not yet been published in the Threads::list, and
2561// hence doesn't need protection from concurrent access at this stage.
2562void JavaThread::verify_not_published() {
2563 // Cannot create a ThreadsListHandle here and check !tlh.includes(this)
2564 // since an unpublished JavaThread doesn't participate in the
2565 // Thread-SMR protocol for keeping a ThreadsList alive.
2566 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!");
2567}
2568#endif
2569
2570// Slow path when the native==>VM/Java barriers detect a safepoint is in
2571// progress or when _suspend_flags is non-zero.
2572// Current thread needs to self-suspend if there is a suspend request and/or
2573// block if a safepoint is in progress.
2574// Async exception ISN'T checked.
2575// Note only the ThreadInVMfromNative transition can call this function
2576// directly and when thread state is _thread_in_native_trans
2577void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2578 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2579
2580 JavaThread *curJT = JavaThread::current();
2581 bool do_self_suspend = thread->is_external_suspend();
2582
2583 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2584
2585 // If JNIEnv proxies are allowed, don't self-suspend if the target
2586 // thread is not the current thread. In older versions of jdbx, jdbx
2587 // threads could call into the VM with another thread's JNIEnv so we
2588 // can be here operating on behalf of a suspended thread (4432884).
2589 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2590 thread->java_suspend_self_with_safepoint_check();
2591 } else {
2592 SafepointMechanism::block_if_requested(curJT);
2593 }
2594
2595 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);)
2596}
2597
2598// Slow path when the native==>VM/Java barriers detect a safepoint is in
2599// progress or when _suspend_flags is non-zero.
2600// Current thread needs to self-suspend if there is a suspend request and/or
2601// block if a safepoint is in progress.
2602// Also check for pending async exception (not including unsafe access error).
2603// Note only the native==>VM/Java barriers can call this function and when
2604// thread state is _thread_in_native_trans.
2605void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2606 check_safepoint_and_suspend_for_native_trans(thread);
2607
2608 if (thread->has_async_exception()) {
2609 // We are in _thread_in_native_trans state, don't handle unsafe
2610 // access error since that may block.
2611 thread->check_and_handle_async_exceptions(false);
2612 }
2613}
2614
2615// This is a variant of the normal
2616// check_special_condition_for_native_trans with slightly different
2617// semantics for use by critical native wrappers. It does all the
2618// normal checks but also performs the transition back into
2619// thread_in_Java state. This is required so that critical natives
2620// can potentially block and perform a GC if they are the last thread
2621// exiting the GCLocker.
2622void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2623 check_special_condition_for_native_trans(thread);
2624
2625 // Finish the transition
2626 thread->set_thread_state(_thread_in_Java);
2627
2628 if (thread->do_critical_native_unlock()) {
2629 ThreadInVMfromJavaNoAsyncException tiv(thread);
2630 GCLocker::unlock_critical(thread);
2631 thread->clear_critical_native_unlock();
2632 }
2633}
2634
2635// We need to guarantee the Threads_lock here, since resumes are not
2636// allowed during safepoint synchronization
2637// Can only resume from an external suspension
2638void JavaThread::java_resume() {
2639 assert_locked_or_safepoint(Threads_lock);
2640
2641 // Sanity check: thread is gone, has started exiting or the thread
2642 // was not externally suspended.
2643 ThreadsListHandle tlh;
2644 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
2645 return;
2646 }
2647
2648 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2649
2650 clear_external_suspend();
2651
2652 if (is_ext_suspended()) {
2653 clear_ext_suspended();
2654 SR_lock()->notify_all();
2655 }
2656}
2657
2658size_t JavaThread::_stack_red_zone_size = 0;
2659size_t JavaThread::_stack_yellow_zone_size = 0;
2660size_t JavaThread::_stack_reserved_zone_size = 0;
2661size_t JavaThread::_stack_shadow_zone_size = 0;
2662
2663void JavaThread::create_stack_guard_pages() {
2664 if (!os::uses_stack_guard_pages() ||
2665 _stack_guard_state != stack_guard_unused ||
2666 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) {
2667 log_info(os, thread)("Stack guard page creation for thread "
2668 UINTX_FORMAT " disabled", os::current_thread_id());
2669 return;
2670 }
2671 address low_addr = stack_end();
2672 size_t len = stack_guard_zone_size();
2673
2674 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page");
2675 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size");
2676
2677 int must_commit = os::must_commit_stack_guard_pages();
2678 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2679
2680 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) {
2681 log_warning(os, thread)("Attempt to allocate stack guard pages failed.");
2682 return;
2683 }
2684
2685 if (os::guard_memory((char *) low_addr, len)) {
2686 _stack_guard_state = stack_guard_enabled;
2687 } else {
2688 log_warning(os, thread)("Attempt to protect stack guard pages failed ("
2689 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2690 if (os::uncommit_memory((char *) low_addr, len)) {
2691 log_warning(os, thread)("Attempt to deallocate stack guard pages failed.");
2692 }
2693 return;
2694 }
2695
2696 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: "
2697 PTR_FORMAT "-" PTR_FORMAT ".",
2698 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2699}
2700
2701void JavaThread::remove_stack_guard_pages() {
2702 assert(Thread::current() == this, "from different thread");
2703 if (_stack_guard_state == stack_guard_unused) return;
2704 address low_addr = stack_end();
2705 size_t len = stack_guard_zone_size();
2706
2707 if (os::must_commit_stack_guard_pages()) {
2708 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2709 _stack_guard_state = stack_guard_unused;
2710 } else {
2711 log_warning(os, thread)("Attempt to deallocate stack guard pages failed ("
2712 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2713 return;
2714 }
2715 } else {
2716 if (_stack_guard_state == stack_guard_unused) return;
2717 if (os::unguard_memory((char *) low_addr, len)) {
2718 _stack_guard_state = stack_guard_unused;
2719 } else {
2720 log_warning(os, thread)("Attempt to unprotect stack guard pages failed ("
2721 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len));
2722 return;
2723 }
2724 }
2725
2726 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: "
2727 PTR_FORMAT "-" PTR_FORMAT ".",
2728 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len));
2729}
2730
2731void JavaThread::enable_stack_reserved_zone() {
2732 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state");
2733
2734 // The base notation is from the stack's point of view, growing downward.
2735 // We need to adjust it to work correctly with guard_memory()
2736 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2737
2738 guarantee(base < stack_base(),"Error calculating stack reserved zone");
2739 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone");
2740
2741 if (os::guard_memory((char *) base, stack_reserved_zone_size())) {
2742 _stack_guard_state = stack_guard_enabled;
2743 } else {
2744 warning("Attempt to guard stack reserved zone failed.");
2745 }
2746 enable_register_stack_guard();
2747}
2748
2749void JavaThread::disable_stack_reserved_zone() {
2750 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state");
2751
2752 // Simply return if called for a thread that does not use guard pages.
2753 if (_stack_guard_state != stack_guard_enabled) return;
2754
2755 // The base notation is from the stack's point of view, growing downward.
2756 // We need to adjust it to work correctly with guard_memory()
2757 address base = stack_reserved_zone_base() - stack_reserved_zone_size();
2758
2759 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) {
2760 _stack_guard_state = stack_guard_reserved_disabled;
2761 } else {
2762 warning("Attempt to unguard stack reserved zone failed.");
2763 }
2764 disable_register_stack_guard();
2765}
2766
2767void JavaThread::enable_stack_yellow_reserved_zone() {
2768 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2769 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2770
2771 // The base notation is from the stacks point of view, growing downward.
2772 // We need to adjust it to work correctly with guard_memory()
2773 address base = stack_red_zone_base();
2774
2775 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2776 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2777
2778 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) {
2779 _stack_guard_state = stack_guard_enabled;
2780 } else {
2781 warning("Attempt to guard stack yellow zone failed.");
2782 }
2783 enable_register_stack_guard();
2784}
2785
2786void JavaThread::disable_stack_yellow_reserved_zone() {
2787 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2788 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled");
2789
2790 // Simply return if called for a thread that does not use guard pages.
2791 if (_stack_guard_state == stack_guard_unused) return;
2792
2793 // The base notation is from the stacks point of view, growing downward.
2794 // We need to adjust it to work correctly with guard_memory()
2795 address base = stack_red_zone_base();
2796
2797 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) {
2798 _stack_guard_state = stack_guard_yellow_reserved_disabled;
2799 } else {
2800 warning("Attempt to unguard stack yellow zone failed.");
2801 }
2802 disable_register_stack_guard();
2803}
2804
2805void JavaThread::enable_stack_red_zone() {
2806 // The base notation is from the stacks point of view, growing downward.
2807 // We need to adjust it to work correctly with guard_memory()
2808 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2809 address base = stack_red_zone_base() - stack_red_zone_size();
2810
2811 guarantee(base < stack_base(), "Error calculating stack red zone");
2812 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2813
2814 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2815 warning("Attempt to guard stack red zone failed.");
2816 }
2817}
2818
2819void JavaThread::disable_stack_red_zone() {
2820 // The base notation is from the stacks point of view, growing downward.
2821 // We need to adjust it to work correctly with guard_memory()
2822 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2823 address base = stack_red_zone_base() - stack_red_zone_size();
2824 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2825 warning("Attempt to unguard stack red zone failed.");
2826 }
2827}
2828
2829void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2830 // ignore is there is no stack
2831 if (!has_last_Java_frame()) return;
2832 // traverse the stack frames. Starts from top frame.
2833 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2834 frame* fr = fst.current();
2835 f(fr, fst.register_map());
2836 }
2837}
2838
2839
2840#ifndef PRODUCT
2841// Deoptimization
2842// Function for testing deoptimization
2843void JavaThread::deoptimize() {
2844 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2845 StackFrameStream fst(this, UseBiasedLocking);
2846 bool deopt = false; // Dump stack only if a deopt actually happens.
2847 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2848 // Iterate over all frames in the thread and deoptimize
2849 for (; !fst.is_done(); fst.next()) {
2850 if (fst.current()->can_be_deoptimized()) {
2851
2852 if (only_at) {
2853 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2854 // consists of comma or carriage return separated numbers so
2855 // search for the current bci in that string.
2856 address pc = fst.current()->pc();
2857 nmethod* nm = (nmethod*) fst.current()->cb();
2858 ScopeDesc* sd = nm->scope_desc_at(pc);
2859 char buffer[8];
2860 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2861 size_t len = strlen(buffer);
2862 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2863 while (found != NULL) {
2864 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2865 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2866 // Check that the bci found is bracketed by terminators.
2867 break;
2868 }
2869 found = strstr(found + 1, buffer);
2870 }
2871 if (!found) {
2872 continue;
2873 }
2874 }
2875
2876 if (DebugDeoptimization && !deopt) {
2877 deopt = true; // One-time only print before deopt
2878 tty->print_cr("[BEFORE Deoptimization]");
2879 trace_frames();
2880 trace_stack();
2881 }
2882 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2883 }
2884 }
2885
2886 if (DebugDeoptimization && deopt) {
2887 tty->print_cr("[AFTER Deoptimization]");
2888 trace_frames();
2889 }
2890}
2891
2892
2893// Make zombies
2894void JavaThread::make_zombies() {
2895 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2896 if (fst.current()->can_be_deoptimized()) {
2897 // it is a Java nmethod
2898 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2899 nm->make_not_entrant();
2900 }
2901 }
2902}
2903#endif // PRODUCT
2904
2905
2906void JavaThread::deoptimized_wrt_marked_nmethods() {
2907 if (!has_last_Java_frame()) return;
2908 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2909 StackFrameStream fst(this, UseBiasedLocking);
2910 for (; !fst.is_done(); fst.next()) {
2911 if (fst.current()->should_be_deoptimized()) {
2912 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2913 }
2914 }
2915}
2916
2917
2918// If the caller is a NamedThread, then remember, in the current scope,
2919// the given JavaThread in its _processed_thread field.
2920class RememberProcessedThread: public StackObj {
2921 NamedThread* _cur_thr;
2922 public:
2923 RememberProcessedThread(JavaThread* jthr) {
2924 Thread* thread = Thread::current();
2925 if (thread->is_Named_thread()) {
2926 _cur_thr = (NamedThread *)thread;
2927 _cur_thr->set_processed_thread(jthr);
2928 } else {
2929 _cur_thr = NULL;
2930 }
2931 }
2932
2933 ~RememberProcessedThread() {
2934 if (_cur_thr) {
2935 _cur_thr->set_processed_thread(NULL);
2936 }
2937 }
2938};
2939
2940void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
2941 // Verify that the deferred card marks have been flushed.
2942 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2943
2944 // Traverse the GCHandles
2945 Thread::oops_do(f, cf);
2946
2947 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2948 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2949
2950 if (has_last_Java_frame()) {
2951 // Record JavaThread to GC thread
2952 RememberProcessedThread rpt(this);
2953
2954 // traverse the registered growable array
2955 if (_array_for_gc != NULL) {
2956 for (int index = 0; index < _array_for_gc->length(); index++) {
2957 f->do_oop(_array_for_gc->adr_at(index));
2958 }
2959 }
2960
2961 // Traverse the monitor chunks
2962 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2963 chunk->oops_do(f);
2964 }
2965
2966 // Traverse the execution stack
2967 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2968 fst.current()->oops_do(f, cf, fst.register_map());
2969 }
2970 }
2971
2972 // callee_target is never live across a gc point so NULL it here should
2973 // it still contain a methdOop.
2974
2975 set_callee_target(NULL);
2976
2977 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2978 // If we have deferred set_locals there might be oops waiting to be
2979 // written
2980 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2981 if (list != NULL) {
2982 for (int i = 0; i < list->length(); i++) {
2983 list->at(i)->oops_do(f);
2984 }
2985 }
2986
2987 // Traverse instance variables at the end since the GC may be moving things
2988 // around using this function
2989 f->do_oop((oop*) &_threadObj);
2990 f->do_oop((oop*) &_vm_result);
2991 f->do_oop((oop*) &_exception_oop);
2992 f->do_oop((oop*) &_pending_async_exception);
2993
2994 if (jvmti_thread_state() != NULL) {
2995 jvmti_thread_state()->oops_do(f);
2996 }
2997}
2998
2999#ifdef ASSERT
3000void JavaThread::verify_states_for_handshake() {
3001 // This checks that the thread has a correct frame state during a handshake.
3002 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3003 (has_last_Java_frame() && java_call_counter() > 0),
3004 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3005 has_last_Java_frame(), java_call_counter());
3006}
3007#endif
3008
3009void JavaThread::nmethods_do(CodeBlobClosure* cf) {
3010 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
3011 (has_last_Java_frame() && java_call_counter() > 0),
3012 "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
3013 has_last_Java_frame(), java_call_counter());
3014
3015 if (has_last_Java_frame()) {
3016 // Traverse the execution stack
3017 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3018 fst.current()->nmethods_do(cf);
3019 }
3020 }
3021}
3022
3023void JavaThread::metadata_do(MetadataClosure* f) {
3024 if (has_last_Java_frame()) {
3025 // Traverse the execution stack to call f() on the methods in the stack
3026 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3027 fst.current()->metadata_do(f);
3028 }
3029 } else if (is_Compiler_thread()) {
3030 // need to walk ciMetadata in current compile tasks to keep alive.
3031 CompilerThread* ct = (CompilerThread*)this;
3032 if (ct->env() != NULL) {
3033 ct->env()->metadata_do(f);
3034 }
3035 CompileTask* task = ct->task();
3036 if (task != NULL) {
3037 task->metadata_do(f);
3038 }
3039 }
3040}
3041
3042// Printing
3043const char* _get_thread_state_name(JavaThreadState _thread_state) {
3044 switch (_thread_state) {
3045 case _thread_uninitialized: return "_thread_uninitialized";
3046 case _thread_new: return "_thread_new";
3047 case _thread_new_trans: return "_thread_new_trans";
3048 case _thread_in_native: return "_thread_in_native";
3049 case _thread_in_native_trans: return "_thread_in_native_trans";
3050 case _thread_in_vm: return "_thread_in_vm";
3051 case _thread_in_vm_trans: return "_thread_in_vm_trans";
3052 case _thread_in_Java: return "_thread_in_Java";
3053 case _thread_in_Java_trans: return "_thread_in_Java_trans";
3054 case _thread_blocked: return "_thread_blocked";
3055 case _thread_blocked_trans: return "_thread_blocked_trans";
3056 default: return "unknown thread state";
3057 }
3058}
3059
3060#ifndef PRODUCT
3061void JavaThread::print_thread_state_on(outputStream *st) const {
3062 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
3063};
3064void JavaThread::print_thread_state() const {
3065 print_thread_state_on(tty);
3066}
3067#endif // PRODUCT
3068
3069// Called by Threads::print() for VM_PrintThreads operation
3070void JavaThread::print_on(outputStream *st, bool print_extended_info) const {
3071 st->print_raw("\"");
3072 st->print_raw(get_thread_name());
3073 st->print_raw("\" ");
3074 oop thread_oop = threadObj();
3075 if (thread_oop != NULL) {
3076 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop));
3077 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
3078 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
3079 }
3080 Thread::print_on(st, print_extended_info);
3081 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
3082 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
3083 if (thread_oop != NULL) {
3084 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
3085 }
3086#ifndef PRODUCT
3087 _safepoint_state->print_on(st);
3088#endif // PRODUCT
3089 if (is_Compiler_thread()) {
3090 CompileTask *task = ((CompilerThread*)this)->task();
3091 if (task != NULL) {
3092 st->print(" Compiling: ");
3093 task->print(st, NULL, true, false);
3094 } else {
3095 st->print(" No compile task");
3096 }
3097 st->cr();
3098 }
3099}
3100
3101void JavaThread::print() const { print_on(tty); }
3102
3103void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const {
3104 st->print("%s", get_thread_name_string(buf, buflen));
3105}
3106
3107// Called by fatal error handler. The difference between this and
3108// JavaThread::print() is that we can't grab lock or allocate memory.
3109void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
3110 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
3111 oop thread_obj = threadObj();
3112 if (thread_obj != NULL) {
3113 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
3114 }
3115 st->print(" [");
3116 st->print("%s", _get_thread_state_name(_thread_state));
3117 if (osthread()) {
3118 st->print(", id=%d", osthread()->thread_id());
3119 }
3120 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
3121 p2i(stack_end()), p2i(stack_base()));
3122 st->print("]");
3123
3124 ThreadsSMRSupport::print_info_on(this, st);
3125 return;
3126}
3127
3128// Verification
3129
3130static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
3131
3132void JavaThread::verify() {
3133 // Verify oops in the thread.
3134 oops_do(&VerifyOopClosure::verify_oop, NULL);
3135
3136 // Verify the stack frames.
3137 frames_do(frame_verify);
3138}
3139
3140// CR 6300358 (sub-CR 2137150)
3141// Most callers of this method assume that it can't return NULL but a
3142// thread may not have a name whilst it is in the process of attaching to
3143// the VM - see CR 6412693, and there are places where a JavaThread can be
3144// seen prior to having it's threadObj set (eg JNI attaching threads and
3145// if vm exit occurs during initialization). These cases can all be accounted
3146// for such that this method never returns NULL.
3147const char* JavaThread::get_thread_name() const {
3148#ifdef ASSERT
3149 // early safepoints can hit while current thread does not yet have TLS
3150 if (!SafepointSynchronize::is_at_safepoint()) {
3151 Thread *cur = Thread::current();
3152 if (!(cur->is_Java_thread() && cur == this)) {
3153 // Current JavaThreads are allowed to get their own name without
3154 // the Threads_lock.
3155 assert_locked_or_safepoint(Threads_lock);
3156 }
3157 }
3158#endif // ASSERT
3159 return get_thread_name_string();
3160}
3161
3162// Returns a non-NULL representation of this thread's name, or a suitable
3163// descriptive string if there is no set name
3164const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
3165 const char* name_str;
3166 oop thread_obj = threadObj();
3167 if (thread_obj != NULL) {
3168 oop name = java_lang_Thread::name(thread_obj);
3169 if (name != NULL) {
3170 if (buf == NULL) {
3171 name_str = java_lang_String::as_utf8_string(name);
3172 } else {
3173 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
3174 }
3175 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
3176 name_str = "<no-name - thread is attaching>";
3177 } else {
3178 name_str = Thread::name();
3179 }
3180 } else {
3181 name_str = Thread::name();
3182 }
3183 assert(name_str != NULL, "unexpected NULL thread name");
3184 return name_str;
3185}
3186
3187
3188const char* JavaThread::get_threadgroup_name() const {
3189 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3190 oop thread_obj = threadObj();
3191 if (thread_obj != NULL) {
3192 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3193 if (thread_group != NULL) {
3194 // ThreadGroup.name can be null
3195 return java_lang_ThreadGroup::name(thread_group);
3196 }
3197 }
3198 return NULL;
3199}
3200
3201const char* JavaThread::get_parent_name() const {
3202 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
3203 oop thread_obj = threadObj();
3204 if (thread_obj != NULL) {
3205 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
3206 if (thread_group != NULL) {
3207 oop parent = java_lang_ThreadGroup::parent(thread_group);
3208 if (parent != NULL) {
3209 // ThreadGroup.name can be null
3210 return java_lang_ThreadGroup::name(parent);
3211 }
3212 }
3213 }
3214 return NULL;
3215}
3216
3217ThreadPriority JavaThread::java_priority() const {
3218 oop thr_oop = threadObj();
3219 if (thr_oop == NULL) return NormPriority; // Bootstrapping
3220 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
3221 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
3222 return priority;
3223}
3224
3225void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
3226
3227 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
3228 // Link Java Thread object <-> C++ Thread
3229
3230 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
3231 // and put it into a new Handle. The Handle "thread_oop" can then
3232 // be used to pass the C++ thread object to other methods.
3233
3234 // Set the Java level thread object (jthread) field of the
3235 // new thread (a JavaThread *) to C++ thread object using the
3236 // "thread_oop" handle.
3237
3238 // Set the thread field (a JavaThread *) of the
3239 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
3240
3241 Handle thread_oop(Thread::current(),
3242 JNIHandles::resolve_non_null(jni_thread));
3243 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
3244 "must be initialized");
3245 set_threadObj(thread_oop());
3246 java_lang_Thread::set_thread(thread_oop(), this);
3247
3248 if (prio == NoPriority) {
3249 prio = java_lang_Thread::priority(thread_oop());
3250 assert(prio != NoPriority, "A valid priority should be present");
3251 }
3252
3253 // Push the Java priority down to the native thread; needs Threads_lock
3254 Thread::set_priority(this, prio);
3255
3256 // Add the new thread to the Threads list and set it in motion.
3257 // We must have threads lock in order to call Threads::add.
3258 // It is crucial that we do not block before the thread is
3259 // added to the Threads list for if a GC happens, then the java_thread oop
3260 // will not be visited by GC.
3261 Threads::add(this);
3262}
3263
3264oop JavaThread::current_park_blocker() {
3265 // Support for JSR-166 locks
3266 oop thread_oop = threadObj();
3267 if (thread_oop != NULL) {
3268 return java_lang_Thread::park_blocker(thread_oop);
3269 }
3270 return NULL;
3271}
3272
3273
3274void JavaThread::print_stack_on(outputStream* st) {
3275 if (!has_last_Java_frame()) return;
3276 ResourceMark rm;
3277 HandleMark hm;
3278
3279 RegisterMap reg_map(this);
3280 vframe* start_vf = last_java_vframe(&reg_map);
3281 int count = 0;
3282 for (vframe* f = start_vf; f != NULL; f = f->sender()) {
3283 if (f->is_java_frame()) {
3284 javaVFrame* jvf = javaVFrame::cast(f);
3285 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
3286
3287 // Print out lock information
3288 if (JavaMonitorsInStackTrace) {
3289 jvf->print_lock_info_on(st, count);
3290 }
3291 } else {
3292 // Ignore non-Java frames
3293 }
3294
3295 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0
3296 count++;
3297 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return;
3298 }
3299}
3300
3301
3302// JVMTI PopFrame support
3303void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
3304 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
3305 if (in_bytes(size_in_bytes) != 0) {
3306 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
3307 _popframe_preserved_args_size = in_bytes(size_in_bytes);
3308 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
3309 }
3310}
3311
3312void* JavaThread::popframe_preserved_args() {
3313 return _popframe_preserved_args;
3314}
3315
3316ByteSize JavaThread::popframe_preserved_args_size() {
3317 return in_ByteSize(_popframe_preserved_args_size);
3318}
3319
3320WordSize JavaThread::popframe_preserved_args_size_in_words() {
3321 int sz = in_bytes(popframe_preserved_args_size());
3322 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3323 return in_WordSize(sz / wordSize);
3324}
3325
3326void JavaThread::popframe_free_preserved_args() {
3327 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3328 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3329 _popframe_preserved_args = NULL;
3330 _popframe_preserved_args_size = 0;
3331}
3332
3333#ifndef PRODUCT
3334
3335void JavaThread::trace_frames() {
3336 tty->print_cr("[Describe stack]");
3337 int frame_no = 1;
3338 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3339 tty->print(" %d. ", frame_no++);
3340 fst.current()->print_value_on(tty, this);
3341 tty->cr();
3342 }
3343}
3344
3345class PrintAndVerifyOopClosure: public OopClosure {
3346 protected:
3347 template <class T> inline void do_oop_work(T* p) {
3348 oop obj = RawAccess<>::oop_load(p);
3349 if (obj == NULL) return;
3350 tty->print(INTPTR_FORMAT ": ", p2i(p));
3351 if (oopDesc::is_oop_or_null(obj)) {
3352 if (obj->is_objArray()) {
3353 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj));
3354 } else {
3355 obj->print();
3356 }
3357 } else {
3358 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj));
3359 }
3360 tty->cr();
3361 }
3362 public:
3363 virtual void do_oop(oop* p) { do_oop_work(p); }
3364 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3365};
3366
3367
3368static void oops_print(frame* f, const RegisterMap *map) {
3369 PrintAndVerifyOopClosure print;
3370 f->print_value();
3371 f->oops_do(&print, NULL, (RegisterMap*)map);
3372}
3373
3374// Print our all the locations that contain oops and whether they are
3375// valid or not. This useful when trying to find the oldest frame
3376// where an oop has gone bad since the frame walk is from youngest to
3377// oldest.
3378void JavaThread::trace_oops() {
3379 tty->print_cr("[Trace oops]");
3380 frames_do(oops_print);
3381}
3382
3383
3384#ifdef ASSERT
3385// Print or validate the layout of stack frames
3386void JavaThread::print_frame_layout(int depth, bool validate_only) {
3387 ResourceMark rm;
3388 PRESERVE_EXCEPTION_MARK;
3389 FrameValues values;
3390 int frame_no = 0;
3391 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3392 fst.current()->describe(values, ++frame_no);
3393 if (depth == frame_no) break;
3394 }
3395 if (validate_only) {
3396 values.validate();
3397 } else {
3398 tty->print_cr("[Describe stack layout]");
3399 values.print(this);
3400 }
3401}
3402#endif
3403
3404void JavaThread::trace_stack_from(vframe* start_vf) {
3405 ResourceMark rm;
3406 int vframe_no = 1;
3407 for (vframe* f = start_vf; f; f = f->sender()) {
3408 if (f->is_java_frame()) {
3409 javaVFrame::cast(f)->print_activation(vframe_no++);
3410 } else {
3411 f->print();
3412 }
3413 if (vframe_no > StackPrintLimit) {
3414 tty->print_cr("...<more frames>...");
3415 return;
3416 }
3417 }
3418}
3419
3420
3421void JavaThread::trace_stack() {
3422 if (!has_last_Java_frame()) return;
3423 ResourceMark rm;
3424 HandleMark hm;
3425 RegisterMap reg_map(this);
3426 trace_stack_from(last_java_vframe(&reg_map));
3427}
3428
3429
3430#endif // PRODUCT
3431
3432
3433javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3434 assert(reg_map != NULL, "a map must be given");
3435 frame f = last_frame();
3436 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3437 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3438 }
3439 return NULL;
3440}
3441
3442
3443Klass* JavaThread::security_get_caller_class(int depth) {
3444 vframeStream vfst(this);
3445 vfst.security_get_caller_frame(depth);
3446 if (!vfst.at_end()) {
3447 return vfst.method()->method_holder();
3448 }
3449 return NULL;
3450}
3451
3452static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3453 assert(thread->is_Compiler_thread(), "must be compiler thread");
3454 CompileBroker::compiler_thread_loop();
3455}
3456
3457static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3458 NMethodSweeper::sweeper_loop();
3459}
3460
3461// Create a CompilerThread
3462CompilerThread::CompilerThread(CompileQueue* queue,
3463 CompilerCounters* counters)
3464 : JavaThread(&compiler_thread_entry) {
3465 _env = NULL;
3466 _log = NULL;
3467 _task = NULL;
3468 _queue = queue;
3469 _counters = counters;
3470 _buffer_blob = NULL;
3471 _compiler = NULL;
3472
3473 // Compiler uses resource area for compilation, let's bias it to mtCompiler
3474 resource_area()->bias_to(mtCompiler);
3475
3476#ifndef PRODUCT
3477 _ideal_graph_printer = NULL;
3478#endif
3479}
3480
3481CompilerThread::~CompilerThread() {
3482 // Delete objects which were allocated on heap.
3483 delete _counters;
3484}
3485
3486bool CompilerThread::can_call_java() const {
3487 return _compiler != NULL && _compiler->is_jvmci();
3488}
3489
3490// Create sweeper thread
3491CodeCacheSweeperThread::CodeCacheSweeperThread()
3492: JavaThread(&sweeper_thread_entry) {
3493 _scanned_compiled_method = NULL;
3494}
3495
3496void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
3497 JavaThread::oops_do(f, cf);
3498 if (_scanned_compiled_method != NULL && cf != NULL) {
3499 // Safepoints can occur when the sweeper is scanning an nmethod so
3500 // process it here to make sure it isn't unloaded in the middle of
3501 // a scan.
3502 cf->do_code_blob(_scanned_compiled_method);
3503 }
3504}
3505
3506void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) {
3507 JavaThread::nmethods_do(cf);
3508 if (_scanned_compiled_method != NULL && cf != NULL) {
3509 // Safepoints can occur when the sweeper is scanning an nmethod so
3510 // process it here to make sure it isn't unloaded in the middle of
3511 // a scan.
3512 cf->do_code_blob(_scanned_compiled_method);
3513 }
3514}
3515
3516
3517// ======= Threads ========
3518
3519// The Threads class links together all active threads, and provides
3520// operations over all threads. It is protected by the Threads_lock,
3521// which is also used in other global contexts like safepointing.
3522// ThreadsListHandles are used to safely perform operations on one
3523// or more threads without the risk of the thread exiting during the
3524// operation.
3525//
3526// Note: The Threads_lock is currently more widely used than we
3527// would like. We are actively migrating Threads_lock uses to other
3528// mechanisms in order to reduce Threads_lock contention.
3529
3530int Threads::_number_of_threads = 0;
3531int Threads::_number_of_non_daemon_threads = 0;
3532int Threads::_return_code = 0;
3533uintx Threads::_thread_claim_token = 1; // Never zero.
3534size_t JavaThread::_stack_size_at_create = 0;
3535
3536#ifdef ASSERT
3537bool Threads::_vm_complete = false;
3538#endif
3539
3540static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
3541 Prefetch::read((void*)addr, prefetch_interval);
3542 return *addr;
3543}
3544
3545// Possibly the ugliest for loop the world has seen. C++ does not allow
3546// multiple types in the declaration section of the for loop. In this case
3547// we are only dealing with pointers and hence can cast them. It looks ugly
3548// but macros are ugly and therefore it's fine to make things absurdly ugly.
3549#define DO_JAVA_THREADS(LIST, X) \
3550 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
3551 *MACRO_list = (JavaThread*)(LIST), \
3552 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
3553 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
3554 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \
3555 MACRO_current_p != MACRO_end; \
3556 MACRO_current_p++, \
3557 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval))
3558
3559// All JavaThreads
3560#define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X)
3561
3562// All NonJavaThreads (i.e., every non-JavaThread in the system).
3563void Threads::non_java_threads_do(ThreadClosure* tc) {
3564 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false);
3565 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
3566 tc->do_thread(njti.current());
3567 }
3568}
3569
3570// All JavaThreads
3571void Threads::java_threads_do(ThreadClosure* tc) {
3572 assert_locked_or_safepoint(Threads_lock);
3573 // ALL_JAVA_THREADS iterates through all JavaThreads.
3574 ALL_JAVA_THREADS(p) {
3575 tc->do_thread(p);
3576 }
3577}
3578
3579void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) {
3580 assert_locked_or_safepoint(Threads_lock);
3581 java_threads_do(tc);
3582 tc->do_thread(VMThread::vm_thread());
3583}
3584
3585// All JavaThreads + all non-JavaThreads (i.e., every thread in the system).
3586void Threads::threads_do(ThreadClosure* tc) {
3587 assert_locked_or_safepoint(Threads_lock);
3588 java_threads_do(tc);
3589 non_java_threads_do(tc);
3590}
3591
3592void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) {
3593 uintx claim_token = Threads::thread_claim_token();
3594 ALL_JAVA_THREADS(p) {
3595 if (p->claim_threads_do(is_par, claim_token)) {
3596 tc->do_thread(p);
3597 }
3598 }
3599 VMThread* vmt = VMThread::vm_thread();
3600 if (vmt->claim_threads_do(is_par, claim_token)) {
3601 tc->do_thread(vmt);
3602 }
3603}
3604
3605// The system initialization in the library has three phases.
3606//
3607// Phase 1: java.lang.System class initialization
3608// java.lang.System is a primordial class loaded and initialized
3609// by the VM early during startup. java.lang.System.<clinit>
3610// only does registerNatives and keeps the rest of the class
3611// initialization work later until thread initialization completes.
3612//
3613// System.initPhase1 initializes the system properties, the static
3614// fields in, out, and err. Set up java signal handlers, OS-specific
3615// system settings, and thread group of the main thread.
3616static void call_initPhase1(TRAPS) {
3617 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3618 JavaValue result(T_VOID);
3619 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(),
3620 vmSymbols::void_method_signature(), CHECK);
3621}
3622
3623// Phase 2. Module system initialization
3624// This will initialize the module system. Only java.base classes
3625// can be loaded until phase 2 completes.
3626//
3627// Call System.initPhase2 after the compiler initialization and jsr292
3628// classes get initialized because module initialization runs a lot of java
3629// code, that for performance reasons, should be compiled. Also, this will
3630// enable the startup code to use lambda and other language features in this
3631// phase and onward.
3632//
3633// After phase 2, The VM will begin search classes from -Xbootclasspath/a.
3634static void call_initPhase2(TRAPS) {
3635 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime));
3636
3637 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3638
3639 JavaValue result(T_INT);
3640 JavaCallArguments args;
3641 args.push_int(DisplayVMOutputToStderr);
3642 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown
3643 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(),
3644 vmSymbols::boolean_boolean_int_signature(), &args, CHECK);
3645 if (result.get_jint() != JNI_OK) {
3646 vm_exit_during_initialization(); // no message or exception
3647 }
3648
3649 universe_post_module_init();
3650}
3651
3652// Phase 3. final setup - set security manager, system class loader and TCCL
3653//
3654// This will instantiate and set the security manager, set the system class
3655// loader as well as the thread context class loader. The security manager
3656// and system class loader may be a custom class loaded from -Xbootclasspath/a,
3657// other modules or the application's classpath.
3658static void call_initPhase3(TRAPS) {
3659 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
3660 JavaValue result(T_VOID);
3661 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(),
3662 vmSymbols::void_method_signature(), CHECK);
3663}
3664
3665void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3666 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime));
3667
3668 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3669 create_vm_init_libraries();
3670 }
3671
3672 initialize_class(vmSymbols::java_lang_String(), CHECK);
3673
3674 // Inject CompactStrings value after the static initializers for String ran.
3675 java_lang_String::set_compact_strings(CompactStrings);
3676
3677 // Initialize java_lang.System (needed before creating the thread)
3678 initialize_class(vmSymbols::java_lang_System(), CHECK);
3679 // The VM creates & returns objects of this class. Make sure it's initialized.
3680 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3681 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3682 Handle thread_group = create_initial_thread_group(CHECK);
3683 Universe::set_main_thread_group(thread_group());
3684 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3685 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3686 main_thread->set_threadObj(thread_object);
3687
3688 // Set thread status to running since main thread has
3689 // been started and running.
3690 java_lang_Thread::set_thread_status(thread_object,
3691 java_lang_Thread::RUNNABLE);
3692
3693 // The VM creates objects of this class.
3694 initialize_class(vmSymbols::java_lang_Module(), CHECK);
3695
3696#ifdef ASSERT
3697 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass();
3698 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized");
3699#endif
3700
3701 // initialize the hardware-specific constants needed by Unsafe
3702 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK);
3703 jdk_internal_misc_UnsafeConstants::set_unsafe_constants();
3704
3705 // The VM preresolves methods to these classes. Make sure that they get initialized
3706 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3707 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3708
3709 // Phase 1 of the system initialization in the library, java.lang.System class initialization
3710 call_initPhase1(CHECK);
3711
3712 // get the Java runtime name after java.lang.System is initialized
3713 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3714 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3715
3716 // an instance of OutOfMemory exception has been allocated earlier
3717 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3718 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3719 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3720 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3721 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3722 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3723 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3724 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3725
3726 // Eager box cache initialization only if AOT is on and any library is loaded.
3727 AOTLoader::initialize_box_caches(CHECK);
3728}
3729
3730void Threads::initialize_jsr292_core_classes(TRAPS) {
3731 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime));
3732
3733 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3734 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK);
3735 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3736 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3737}
3738
3739jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3740 extern void JDK_Version_init();
3741
3742 // Preinitialize version info.
3743 VM_Version::early_initialize();
3744
3745 // Check version
3746 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3747
3748 // Initialize library-based TLS
3749 ThreadLocalStorage::init();
3750
3751 // Initialize the output stream module
3752 ostream_init();
3753
3754 // Process java launcher properties.
3755 Arguments::process_sun_java_launcher_properties(args);
3756
3757 // Initialize the os module
3758 os::init();
3759
3760 // Record VM creation timing statistics
3761 TraceVmCreationTime create_vm_timer;
3762 create_vm_timer.start();
3763
3764 // Initialize system properties.
3765 Arguments::init_system_properties();
3766
3767 // So that JDK version can be used as a discriminator when parsing arguments
3768 JDK_Version_init();
3769
3770 // Update/Initialize System properties after JDK version number is known
3771 Arguments::init_version_specific_system_properties();
3772
3773 // Make sure to initialize log configuration *before* parsing arguments
3774 LogConfiguration::initialize(create_vm_timer.begin_time());
3775
3776 // Parse arguments
3777 // Note: this internally calls os::init_container_support()
3778 jint parse_result = Arguments::parse(args);
3779 if (parse_result != JNI_OK) return parse_result;
3780
3781 os::init_before_ergo();
3782
3783 jint ergo_result = Arguments::apply_ergo();
3784 if (ergo_result != JNI_OK) return ergo_result;
3785
3786 // Final check of all ranges after ergonomics which may change values.
3787 if (!JVMFlagRangeList::check_ranges()) {
3788 return JNI_EINVAL;
3789 }
3790
3791 // Final check of all 'AfterErgo' constraints after ergonomics which may change values.
3792 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo);
3793 if (!constraint_result) {
3794 return JNI_EINVAL;
3795 }
3796
3797 JVMFlagWriteableList::mark_startup();
3798
3799 if (PauseAtStartup) {
3800 os::pause();
3801 }
3802
3803 HOTSPOT_VM_INIT_BEGIN();
3804
3805 // Timing (must come after argument parsing)
3806 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime));
3807
3808 // Initialize the os module after parsing the args
3809 jint os_init_2_result = os::init_2();
3810 if (os_init_2_result != JNI_OK) return os_init_2_result;
3811
3812#ifdef CAN_SHOW_REGISTERS_ON_ASSERT
3813 // Initialize assert poison page mechanism.
3814 if (ShowRegistersOnAssert) {
3815 initialize_assert_poison();
3816 }
3817#endif // CAN_SHOW_REGISTERS_ON_ASSERT
3818
3819 SafepointMechanism::initialize();
3820
3821 jint adjust_after_os_result = Arguments::adjust_after_os();
3822 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3823
3824 // Initialize output stream logging
3825 ostream_init_log();
3826
3827 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3828 // Must be before create_vm_init_agents()
3829 if (Arguments::init_libraries_at_startup()) {
3830 convert_vm_init_libraries_to_agents();
3831 }
3832
3833 // Launch -agentlib/-agentpath and converted -Xrun agents
3834 if (Arguments::init_agents_at_startup()) {
3835 create_vm_init_agents();
3836 }
3837
3838 // Initialize Threads state
3839 _number_of_threads = 0;
3840 _number_of_non_daemon_threads = 0;
3841
3842 // Initialize global data structures and create system classes in heap
3843 vm_init_globals();
3844
3845#if INCLUDE_JVMCI
3846 if (JVMCICounterSize > 0) {
3847 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI);
3848 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize);
3849 } else {
3850 JavaThread::_jvmci_old_thread_counters = NULL;
3851 }
3852#endif // INCLUDE_JVMCI
3853
3854 // Attach the main thread to this os thread
3855 JavaThread* main_thread = new JavaThread();
3856 main_thread->set_thread_state(_thread_in_vm);
3857 main_thread->initialize_thread_current();
3858 // must do this before set_active_handles
3859 main_thread->record_stack_base_and_size();
3860 main_thread->register_thread_stack_with_NMT();
3861 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3862
3863 if (!main_thread->set_as_starting_thread()) {
3864 vm_shutdown_during_initialization(
3865 "Failed necessary internal allocation. Out of swap space");
3866 main_thread->smr_delete();
3867 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3868 return JNI_ENOMEM;
3869 }
3870
3871 // Enable guard page *after* os::create_main_thread(), otherwise it would
3872 // crash Linux VM, see notes in os_linux.cpp.
3873 main_thread->create_stack_guard_pages();
3874
3875 // Initialize Java-Level synchronization subsystem
3876 ObjectMonitor::Initialize();
3877
3878 // Initialize global modules
3879 jint status = init_globals();
3880 if (status != JNI_OK) {
3881 main_thread->smr_delete();
3882 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3883 return status;
3884 }
3885
3886 JFR_ONLY(Jfr::on_vm_init();)
3887
3888 // Should be done after the heap is fully created
3889 main_thread->cache_global_variables();
3890
3891 HandleMark hm;
3892
3893 { MutexLocker mu(Threads_lock);
3894 Threads::add(main_thread);
3895 }
3896
3897 // Any JVMTI raw monitors entered in onload will transition into
3898 // real raw monitor. VM is setup enough here for raw monitor enter.
3899 JvmtiExport::transition_pending_onload_raw_monitors();
3900
3901 // Create the VMThread
3902 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime));
3903
3904 VMThread::create();
3905 Thread* vmthread = VMThread::vm_thread();
3906
3907 if (!os::create_thread(vmthread, os::vm_thread)) {
3908 vm_exit_during_initialization("Cannot create VM thread. "
3909 "Out of system resources.");
3910 }
3911
3912 // Wait for the VM thread to become ready, and VMThread::run to initialize
3913 // Monitors can have spurious returns, must always check another state flag
3914 {
3915 MonitorLocker ml(Notify_lock);
3916 os::start_thread(vmthread);
3917 while (vmthread->active_handles() == NULL) {
3918 ml.wait();
3919 }
3920 }
3921 }
3922
3923 assert(Universe::is_fully_initialized(), "not initialized");
3924 if (VerifyDuringStartup) {
3925 // Make sure we're starting with a clean slate.
3926 VM_Verify verify_op;
3927 VMThread::execute(&verify_op);
3928 }
3929
3930 // We need this to update the java.vm.info property in case any flags used
3931 // to initially define it have been changed. This is needed for both CDS and
3932 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info
3933 // is initially computed. See Abstract_VM_Version::vm_info_string().
3934 // This update must happen before we initialize the java classes, but
3935 // after any initialization logic that might modify the flags.
3936 Arguments::update_vm_info_property(VM_Version::vm_info_string());
3937
3938 Thread* THREAD = Thread::current();
3939
3940 // Always call even when there are not JVMTI environments yet, since environments
3941 // may be attached late and JVMTI must track phases of VM execution
3942 JvmtiExport::enter_early_start_phase();
3943
3944 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3945 JvmtiExport::post_early_vm_start();
3946
3947 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3948
3949 quicken_jni_functions();
3950
3951 // No more stub generation allowed after that point.
3952 StubCodeDesc::freeze();
3953
3954 // Set flag that basic initialization has completed. Used by exceptions and various
3955 // debug stuff, that does not work until all basic classes have been initialized.
3956 set_init_completed();
3957
3958 LogConfiguration::post_initialize();
3959 Metaspace::post_initialize();
3960
3961 HOTSPOT_VM_INIT_END();
3962
3963 // record VM initialization completion time
3964#if INCLUDE_MANAGEMENT
3965 Management::record_vm_init_completed();
3966#endif // INCLUDE_MANAGEMENT
3967
3968 // Signal Dispatcher needs to be started before VMInit event is posted
3969 os::initialize_jdk_signal_support(CHECK_JNI_ERR);
3970
3971 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3972 if (!DisableAttachMechanism) {
3973 AttachListener::vm_start();
3974 if (StartAttachListener || AttachListener::init_at_startup()) {
3975 AttachListener::init();
3976 }
3977 }
3978
3979 // Launch -Xrun agents
3980 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3981 // back-end can launch with -Xdebug -Xrunjdwp.
3982 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3983 create_vm_init_libraries();
3984 }
3985
3986 if (CleanChunkPoolAsync) {
3987 Chunk::start_chunk_pool_cleaner_task();
3988 }
3989
3990
3991 // initialize compiler(s)
3992#if defined(COMPILER1) || COMPILER2_OR_JVMCI
3993#if INCLUDE_JVMCI
3994 bool force_JVMCI_intialization = false;
3995 if (EnableJVMCI) {
3996 // Initialize JVMCI eagerly when it is explicitly requested.
3997 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled.
3998 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig;
3999
4000 if (!force_JVMCI_intialization) {
4001 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
4002 // compilations via JVMCI will not actually block until JVMCI is initialized.
4003 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
4004 }
4005 }
4006#endif
4007 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR);
4008 // Postpone completion of compiler initialization to after JVMCI
4009 // is initialized to avoid timeouts of blocking compilations.
4010 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) {
4011 CompileBroker::compilation_init_phase2();
4012 }
4013#endif
4014
4015 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
4016 // It is done after compilers are initialized, because otherwise compilations of
4017 // signature polymorphic MH intrinsics can be missed
4018 // (see SystemDictionary::find_method_handle_intrinsic).
4019 initialize_jsr292_core_classes(CHECK_JNI_ERR);
4020
4021 // This will initialize the module system. Only java.base classes can be
4022 // loaded until phase 2 completes
4023 call_initPhase2(CHECK_JNI_ERR);
4024
4025 // Always call even when there are not JVMTI environments yet, since environments
4026 // may be attached late and JVMTI must track phases of VM execution
4027 JvmtiExport::enter_start_phase();
4028
4029 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
4030 JvmtiExport::post_vm_start();
4031
4032 // Final system initialization including security manager and system class loader
4033 call_initPhase3(CHECK_JNI_ERR);
4034
4035 // cache the system and platform class loaders
4036 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR);
4037
4038#if INCLUDE_CDS
4039 // capture the module path info from the ModuleEntryTable
4040 ClassLoader::initialize_module_path(THREAD);
4041#endif
4042
4043#if INCLUDE_JVMCI
4044 if (force_JVMCI_intialization) {
4045 JVMCI::initialize_compiler(CHECK_JNI_ERR);
4046 CompileBroker::compilation_init_phase2();
4047 }
4048#endif
4049
4050 // Always call even when there are not JVMTI environments yet, since environments
4051 // may be attached late and JVMTI must track phases of VM execution
4052 JvmtiExport::enter_live_phase();
4053
4054 // Make perfmemory accessible
4055 PerfMemory::set_accessible(true);
4056
4057 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
4058 JvmtiExport::post_vm_initialized();
4059
4060 JFR_ONLY(Jfr::on_vm_start();)
4061
4062#if INCLUDE_MANAGEMENT
4063 Management::initialize(THREAD);
4064
4065 if (HAS_PENDING_EXCEPTION) {
4066 // management agent fails to start possibly due to
4067 // configuration problem and is responsible for printing
4068 // stack trace if appropriate. Simply exit VM.
4069 vm_exit(1);
4070 }
4071#endif // INCLUDE_MANAGEMENT
4072
4073 if (MemProfiling) MemProfiler::engage();
4074 StatSampler::engage();
4075 if (CheckJNICalls) JniPeriodicChecker::engage();
4076
4077 BiasedLocking::init();
4078
4079#if INCLUDE_RTM_OPT
4080 RTMLockingCounters::init();
4081#endif
4082
4083 call_postVMInitHook(THREAD);
4084 // The Java side of PostVMInitHook.run must deal with all
4085 // exceptions and provide means of diagnosis.
4086 if (HAS_PENDING_EXCEPTION) {
4087 CLEAR_PENDING_EXCEPTION;
4088 }
4089
4090 {
4091 MutexLocker ml(PeriodicTask_lock);
4092 // Make sure the WatcherThread can be started by WatcherThread::start()
4093 // or by dynamic enrollment.
4094 WatcherThread::make_startable();
4095 // Start up the WatcherThread if there are any periodic tasks
4096 // NOTE: All PeriodicTasks should be registered by now. If they
4097 // aren't, late joiners might appear to start slowly (we might
4098 // take a while to process their first tick).
4099 if (PeriodicTask::num_tasks() > 0) {
4100 WatcherThread::start();
4101 }
4102 }
4103
4104 create_vm_timer.end();
4105#ifdef ASSERT
4106 _vm_complete = true;
4107#endif
4108
4109 if (DumpSharedSpaces) {
4110 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
4111 ShouldNotReachHere();
4112 }
4113
4114 return JNI_OK;
4115}
4116
4117// type for the Agent_OnLoad and JVM_OnLoad entry points
4118extern "C" {
4119 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
4120}
4121// Find a command line agent library and return its entry point for
4122// -agentlib: -agentpath: -Xrun
4123// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
4124static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
4125 const char *on_load_symbols[],
4126 size_t num_symbol_entries) {
4127 OnLoadEntry_t on_load_entry = NULL;
4128 void *library = NULL;
4129
4130 if (!agent->valid()) {
4131 char buffer[JVM_MAXPATHLEN];
4132 char ebuf[1024] = "";
4133 const char *name = agent->name();
4134 const char *msg = "Could not find agent library ";
4135
4136 // First check to see if agent is statically linked into executable
4137 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
4138 library = agent->os_lib();
4139 } else if (agent->is_absolute_path()) {
4140 library = os::dll_load(name, ebuf, sizeof ebuf);
4141 if (library == NULL) {
4142 const char *sub_msg = " in absolute path, with error: ";
4143 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
4144 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4145 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4146 // If we can't find the agent, exit.
4147 vm_exit_during_initialization(buf, NULL);
4148 FREE_C_HEAP_ARRAY(char, buf);
4149 }
4150 } else {
4151 // Try to load the agent from the standard dll directory
4152 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(),
4153 name)) {
4154 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4155 }
4156 if (library == NULL) { // Try the library path directory.
4157 if (os::dll_build_name(buffer, sizeof(buffer), name)) {
4158 library = os::dll_load(buffer, ebuf, sizeof ebuf);
4159 }
4160 if (library == NULL) {
4161 const char *sub_msg = " on the library path, with error: ";
4162 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image.";
4163
4164 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) +
4165 strlen(ebuf) + strlen(sub_msg2) + 1;
4166 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
4167 if (!agent->is_instrument_lib()) {
4168 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
4169 } else {
4170 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2);
4171 }
4172 // If we can't find the agent, exit.
4173 vm_exit_during_initialization(buf, NULL);
4174 FREE_C_HEAP_ARRAY(char, buf);
4175 }
4176 }
4177 }
4178 agent->set_os_lib(library);
4179 agent->set_valid();
4180 }
4181
4182 // Find the OnLoad function.
4183 on_load_entry =
4184 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
4185 false,
4186 on_load_symbols,
4187 num_symbol_entries));
4188 return on_load_entry;
4189}
4190
4191// Find the JVM_OnLoad entry point
4192static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
4193 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
4194 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4195}
4196
4197// Find the Agent_OnLoad entry point
4198static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
4199 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
4200 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
4201}
4202
4203// For backwards compatibility with -Xrun
4204// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
4205// treated like -agentpath:
4206// Must be called before agent libraries are created
4207void Threads::convert_vm_init_libraries_to_agents() {
4208 AgentLibrary* agent;
4209 AgentLibrary* next;
4210
4211 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
4212 next = agent->next(); // cache the next agent now as this agent may get moved off this list
4213 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4214
4215 // If there is an JVM_OnLoad function it will get called later,
4216 // otherwise see if there is an Agent_OnLoad
4217 if (on_load_entry == NULL) {
4218 on_load_entry = lookup_agent_on_load(agent);
4219 if (on_load_entry != NULL) {
4220 // switch it to the agent list -- so that Agent_OnLoad will be called,
4221 // JVM_OnLoad won't be attempted and Agent_OnUnload will
4222 Arguments::convert_library_to_agent(agent);
4223 } else {
4224 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
4225 }
4226 }
4227 }
4228}
4229
4230// Create agents for -agentlib: -agentpath: and converted -Xrun
4231// Invokes Agent_OnLoad
4232// Called very early -- before JavaThreads exist
4233void Threads::create_vm_init_agents() {
4234 extern struct JavaVM_ main_vm;
4235 AgentLibrary* agent;
4236
4237 JvmtiExport::enter_onload_phase();
4238
4239 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4240 // CDS dumping does not support native JVMTI agent.
4241 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified.
4242 if (DumpSharedSpaces || DynamicDumpSharedSpaces) {
4243 if(!agent->is_instrument_lib()) {
4244 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name());
4245 } else if (!AllowArchivingWithJavaAgent) {
4246 vm_exit_during_cds_dumping(
4247 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping");
4248 }
4249 }
4250
4251 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
4252
4253 if (on_load_entry != NULL) {
4254 // Invoke the Agent_OnLoad function
4255 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4256 if (err != JNI_OK) {
4257 vm_exit_during_initialization("agent library failed to init", agent->name());
4258 }
4259 } else {
4260 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
4261 }
4262 }
4263
4264 JvmtiExport::enter_primordial_phase();
4265}
4266
4267extern "C" {
4268 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
4269}
4270
4271void Threads::shutdown_vm_agents() {
4272 // Send any Agent_OnUnload notifications
4273 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
4274 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
4275 extern struct JavaVM_ main_vm;
4276 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
4277
4278 // Find the Agent_OnUnload function.
4279 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
4280 os::find_agent_function(agent,
4281 false,
4282 on_unload_symbols,
4283 num_symbol_entries));
4284
4285 // Invoke the Agent_OnUnload function
4286 if (unload_entry != NULL) {
4287 JavaThread* thread = JavaThread::current();
4288 ThreadToNativeFromVM ttn(thread);
4289 HandleMark hm(thread);
4290 (*unload_entry)(&main_vm);
4291 }
4292 }
4293}
4294
4295// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
4296// Invokes JVM_OnLoad
4297void Threads::create_vm_init_libraries() {
4298 extern struct JavaVM_ main_vm;
4299 AgentLibrary* agent;
4300
4301 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
4302 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
4303
4304 if (on_load_entry != NULL) {
4305 // Invoke the JVM_OnLoad function
4306 JavaThread* thread = JavaThread::current();
4307 ThreadToNativeFromVM ttn(thread);
4308 HandleMark hm(thread);
4309 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
4310 if (err != JNI_OK) {
4311 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
4312 }
4313 } else {
4314 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
4315 }
4316 }
4317}
4318
4319
4320// Last thread running calls java.lang.Shutdown.shutdown()
4321void JavaThread::invoke_shutdown_hooks() {
4322 HandleMark hm(this);
4323
4324 // We could get here with a pending exception, if so clear it now.
4325 if (this->has_pending_exception()) {
4326 this->clear_pending_exception();
4327 }
4328
4329 EXCEPTION_MARK;
4330 Klass* shutdown_klass =
4331 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
4332 THREAD);
4333 if (shutdown_klass != NULL) {
4334 // SystemDictionary::resolve_or_null will return null if there was
4335 // an exception. If we cannot load the Shutdown class, just don't
4336 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
4337 // won't be run. Note that if a shutdown hook was registered,
4338 // the Shutdown class would have already been loaded
4339 // (Runtime.addShutdownHook will load it).
4340 JavaValue result(T_VOID);
4341 JavaCalls::call_static(&result,
4342 shutdown_klass,
4343 vmSymbols::shutdown_name(),
4344 vmSymbols::void_method_signature(),
4345 THREAD);
4346 }
4347 CLEAR_PENDING_EXCEPTION;
4348}
4349
4350// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
4351// the program falls off the end of main(). Another VM exit path is through
4352// vm_exit() when the program calls System.exit() to return a value or when
4353// there is a serious error in VM. The two shutdown paths are not exactly
4354// the same, but they share Shutdown.shutdown() at Java level and before_exit()
4355// and VM_Exit op at VM level.
4356//
4357// Shutdown sequence:
4358// + Shutdown native memory tracking if it is on
4359// + Wait until we are the last non-daemon thread to execute
4360// <-- every thing is still working at this moment -->
4361// + Call java.lang.Shutdown.shutdown(), which will invoke Java level
4362// shutdown hooks
4363// + Call before_exit(), prepare for VM exit
4364// > run VM level shutdown hooks (they are registered through JVM_OnExit(),
4365// currently the only user of this mechanism is File.deleteOnExit())
4366// > stop StatSampler, watcher thread, CMS threads,
4367// post thread end and vm death events to JVMTI,
4368// stop signal thread
4369// + Call JavaThread::exit(), it will:
4370// > release JNI handle blocks, remove stack guard pages
4371// > remove this thread from Threads list
4372// <-- no more Java code from this thread after this point -->
4373// + Stop VM thread, it will bring the remaining VM to a safepoint and stop
4374// the compiler threads at safepoint
4375// <-- do not use anything that could get blocked by Safepoint -->
4376// + Disable tracing at JNI/JVM barriers
4377// + Set _vm_exited flag for threads that are still running native code
4378// + Call exit_globals()
4379// > deletes tty
4380// > deletes PerfMemory resources
4381// + Delete this thread
4382// + Return to caller
4383
4384bool Threads::destroy_vm() {
4385 JavaThread* thread = JavaThread::current();
4386
4387#ifdef ASSERT
4388 _vm_complete = false;
4389#endif
4390 // Wait until we are the last non-daemon thread to execute
4391 { MonitorLocker nu(Threads_lock);
4392 while (Threads::number_of_non_daemon_threads() > 1)
4393 // This wait should make safepoint checks, wait without a timeout,
4394 // and wait as a suspend-equivalent condition.
4395 nu.wait(0, Mutex::_as_suspend_equivalent_flag);
4396 }
4397
4398 EventShutdown e;
4399 if (e.should_commit()) {
4400 e.set_reason("No remaining non-daemon Java threads");
4401 e.commit();
4402 }
4403
4404 // Hang forever on exit if we are reporting an error.
4405 if (ShowMessageBoxOnError && VMError::is_error_reported()) {
4406 os::infinite_sleep();
4407 }
4408 os::wait_for_keypress_at_exit();
4409
4410 // run Java level shutdown hooks
4411 thread->invoke_shutdown_hooks();
4412
4413 before_exit(thread);
4414
4415 thread->exit(true);
4416
4417 // Stop VM thread.
4418 {
4419 // 4945125 The vm thread comes to a safepoint during exit.
4420 // GC vm_operations can get caught at the safepoint, and the
4421 // heap is unparseable if they are caught. Grab the Heap_lock
4422 // to prevent this. The GC vm_operations will not be able to
4423 // queue until after the vm thread is dead. After this point,
4424 // we'll never emerge out of the safepoint before the VM exits.
4425
4426 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag);
4427
4428 VMThread::wait_for_vm_thread_exit();
4429 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
4430 VMThread::destroy();
4431 }
4432
4433 // Now, all Java threads are gone except daemon threads. Daemon threads
4434 // running Java code or in VM are stopped by the Safepoint. However,
4435 // daemon threads executing native code are still running. But they
4436 // will be stopped at native=>Java/VM barriers. Note that we can't
4437 // simply kill or suspend them, as it is inherently deadlock-prone.
4438
4439 VM_Exit::set_vm_exited();
4440
4441 // Clean up ideal graph printers after the VMThread has started
4442 // the final safepoint which will block all the Compiler threads.
4443 // Note that this Thread has already logically exited so the
4444 // clean_up() function's use of a JavaThreadIteratorWithHandle
4445 // would be a problem except set_vm_exited() has remembered the
4446 // shutdown thread which is granted a policy exception.
4447#if defined(COMPILER2) && !defined(PRODUCT)
4448 IdealGraphPrinter::clean_up();
4449#endif
4450
4451 notify_vm_shutdown();
4452
4453 // exit_globals() will delete tty
4454 exit_globals();
4455
4456 // We are after VM_Exit::set_vm_exited() so we can't call
4457 // thread->smr_delete() or we will block on the Threads_lock.
4458 // Deleting the shutdown thread here is safe because another
4459 // JavaThread cannot have an active ThreadsListHandle for
4460 // this JavaThread.
4461 delete thread;
4462
4463#if INCLUDE_JVMCI
4464 if (JVMCICounterSize > 0) {
4465 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
4466 }
4467#endif
4468
4469 LogConfiguration::finalize();
4470
4471 return true;
4472}
4473
4474
4475jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
4476 if (version == JNI_VERSION_1_1) return JNI_TRUE;
4477 return is_supported_jni_version(version);
4478}
4479
4480
4481jboolean Threads::is_supported_jni_version(jint version) {
4482 if (version == JNI_VERSION_1_2) return JNI_TRUE;
4483 if (version == JNI_VERSION_1_4) return JNI_TRUE;
4484 if (version == JNI_VERSION_1_6) return JNI_TRUE;
4485 if (version == JNI_VERSION_1_8) return JNI_TRUE;
4486 if (version == JNI_VERSION_9) return JNI_TRUE;
4487 if (version == JNI_VERSION_10) return JNI_TRUE;
4488 return JNI_FALSE;
4489}
4490
4491
4492void Threads::add(JavaThread* p, bool force_daemon) {
4493 // The threads lock must be owned at this point
4494 assert(Threads_lock->owned_by_self(), "must have threads lock");
4495
4496 BarrierSet::barrier_set()->on_thread_attach(p);
4497
4498 // Once a JavaThread is added to the Threads list, smr_delete() has
4499 // to be used to delete it. Otherwise we can just delete it directly.
4500 p->set_on_thread_list();
4501
4502 _number_of_threads++;
4503 oop threadObj = p->threadObj();
4504 bool daemon = true;
4505 // Bootstrapping problem: threadObj can be null for initial
4506 // JavaThread (or for threads attached via JNI)
4507 if ((!force_daemon) && !is_daemon((threadObj))) {
4508 _number_of_non_daemon_threads++;
4509 daemon = false;
4510 }
4511
4512 ThreadService::add_thread(p, daemon);
4513
4514 // Maintain fast thread list
4515 ThreadsSMRSupport::add_thread(p);
4516
4517 // Possible GC point.
4518 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
4519}
4520
4521void Threads::remove(JavaThread* p, bool is_daemon) {
4522
4523 // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread.
4524 ObjectSynchronizer::omFlush(p);
4525
4526 // Extra scope needed for Thread_lock, so we can check
4527 // that we do not remove thread without safepoint code notice
4528 { MonitorLocker ml(Threads_lock);
4529
4530 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present");
4531
4532 // Maintain fast thread list
4533 ThreadsSMRSupport::remove_thread(p);
4534
4535 _number_of_threads--;
4536 if (!is_daemon) {
4537 _number_of_non_daemon_threads--;
4538
4539 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4540 // on destroy_vm will wake up.
4541 if (number_of_non_daemon_threads() == 1) {
4542 ml.notify_all();
4543 }
4544 }
4545 ThreadService::remove_thread(p, is_daemon);
4546
4547 // Make sure that safepoint code disregard this thread. This is needed since
4548 // the thread might mess around with locks after this point. This can cause it
4549 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4550 // of this thread since it is removed from the queue.
4551 p->set_terminated_value();
4552 } // unlock Threads_lock
4553
4554 // Since Events::log uses a lock, we grab it outside the Threads_lock
4555 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
4556}
4557
4558// Operations on the Threads list for GC. These are not explicitly locked,
4559// but the garbage collector must provide a safe context for them to run.
4560// In particular, these things should never be called when the Threads_lock
4561// is held by some other thread. (Note: the Safepoint abstraction also
4562// uses the Threads_lock to guarantee this property. It also makes sure that
4563// all threads gets blocked when exiting or starting).
4564
4565void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) {
4566 ALL_JAVA_THREADS(p) {
4567 p->oops_do(f, cf);
4568 }
4569 VMThread::vm_thread()->oops_do(f, cf);
4570}
4571
4572void Threads::change_thread_claim_token() {
4573 if (++_thread_claim_token == 0) {
4574 // On overflow of the token counter, there is a risk of future
4575 // collisions between a new global token value and a stale token
4576 // for a thread, because not all iterations visit all threads.
4577 // (Though it's pretty much a theoretical concern for non-trivial
4578 // token counter sizes.) To deal with the possibility, reset all
4579 // the thread tokens to zero on global token overflow.
4580 struct ResetClaims : public ThreadClosure {
4581 virtual void do_thread(Thread* t) {
4582 t->claim_threads_do(false, 0);
4583 }
4584 } reset_claims;
4585 Threads::threads_do(&reset_claims);
4586 // On overflow, update the global token to non-zero, to
4587 // avoid the special "never claimed" initial thread value.
4588 _thread_claim_token = 1;
4589 }
4590}
4591
4592#ifdef ASSERT
4593void assert_thread_claimed(const char* kind, Thread* t, uintx expected) {
4594 const uintx token = t->threads_do_token();
4595 assert(token == expected,
4596 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != "
4597 UINTX_FORMAT, kind, p2i(t), token, expected);
4598}
4599
4600void Threads::assert_all_threads_claimed() {
4601 ALL_JAVA_THREADS(p) {
4602 assert_thread_claimed("Thread", p, _thread_claim_token);
4603 }
4604 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token);
4605}
4606#endif // ASSERT
4607
4608class ParallelOopsDoThreadClosure : public ThreadClosure {
4609private:
4610 OopClosure* _f;
4611 CodeBlobClosure* _cf;
4612public:
4613 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {}
4614 void do_thread(Thread* t) {
4615 t->oops_do(_f, _cf);
4616 }
4617};
4618
4619void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) {
4620 ParallelOopsDoThreadClosure tc(f, cf);
4621 possibly_parallel_threads_do(is_par, &tc);
4622}
4623
4624void Threads::nmethods_do(CodeBlobClosure* cf) {
4625 ALL_JAVA_THREADS(p) {
4626 // This is used by the code cache sweeper to mark nmethods that are active
4627 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid
4628 // marking CodeCacheSweeperThread::_scanned_compiled_method as active.
4629 if(!p->is_Code_cache_sweeper_thread()) {
4630 p->nmethods_do(cf);
4631 }
4632 }
4633}
4634
4635void Threads::metadata_do(MetadataClosure* f) {
4636 ALL_JAVA_THREADS(p) {
4637 p->metadata_do(f);
4638 }
4639}
4640
4641class ThreadHandlesClosure : public ThreadClosure {
4642 void (*_f)(Metadata*);
4643 public:
4644 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4645 virtual void do_thread(Thread* thread) {
4646 thread->metadata_handles_do(_f);
4647 }
4648};
4649
4650void Threads::metadata_handles_do(void f(Metadata*)) {
4651 // Only walk the Handles in Thread.
4652 ThreadHandlesClosure handles_closure(f);
4653 threads_do(&handles_closure);
4654}
4655
4656void Threads::deoptimized_wrt_marked_nmethods() {
4657 ALL_JAVA_THREADS(p) {
4658 p->deoptimized_wrt_marked_nmethods();
4659 }
4660}
4661
4662
4663// Get count Java threads that are waiting to enter the specified monitor.
4664GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
4665 int count,
4666 address monitor) {
4667 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4668
4669 int i = 0;
4670 DO_JAVA_THREADS(t_list, p) {
4671 if (!p->can_call_java()) continue;
4672
4673 address pending = (address)p->current_pending_monitor();
4674 if (pending == monitor) { // found a match
4675 if (i < count) result->append(p); // save the first count matches
4676 i++;
4677 }
4678 }
4679
4680 return result;
4681}
4682
4683
4684JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
4685 address owner) {
4686 // NULL owner means not locked so we can skip the search
4687 if (owner == NULL) return NULL;
4688
4689 DO_JAVA_THREADS(t_list, p) {
4690 // first, see if owner is the address of a Java thread
4691 if (owner == (address)p) return p;
4692 }
4693
4694 // Cannot assert on lack of success here since this function may be
4695 // used by code that is trying to report useful problem information
4696 // like deadlock detection.
4697 if (UseHeavyMonitors) return NULL;
4698
4699 // If we didn't find a matching Java thread and we didn't force use of
4700 // heavyweight monitors, then the owner is the stack address of the
4701 // Lock Word in the owning Java thread's stack.
4702 //
4703 JavaThread* the_owner = NULL;
4704 DO_JAVA_THREADS(t_list, q) {
4705 if (q->is_lock_owned(owner)) {
4706 the_owner = q;
4707 break;
4708 }
4709 }
4710
4711 // cannot assert on lack of success here; see above comment
4712 return the_owner;
4713}
4714
4715// Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4716void Threads::print_on(outputStream* st, bool print_stacks,
4717 bool internal_format, bool print_concurrent_locks,
4718 bool print_extended_info) {
4719 char buf[32];
4720 st->print_raw_cr(os::local_time_string(buf, sizeof(buf)));
4721
4722 st->print_cr("Full thread dump %s (%s %s):",
4723 VM_Version::vm_name(),
4724 VM_Version::vm_release(),
4725 VM_Version::vm_info_string());
4726 st->cr();
4727
4728#if INCLUDE_SERVICES
4729 // Dump concurrent locks
4730 ConcurrentLocksDump concurrent_locks;
4731 if (print_concurrent_locks) {
4732 concurrent_locks.dump_at_safepoint();
4733 }
4734#endif // INCLUDE_SERVICES
4735
4736 ThreadsSMRSupport::print_info_on(st);
4737 st->cr();
4738
4739 ALL_JAVA_THREADS(p) {
4740 ResourceMark rm;
4741 p->print_on(st, print_extended_info);
4742 if (print_stacks) {
4743 if (internal_format) {
4744 p->trace_stack();
4745 } else {
4746 p->print_stack_on(st);
4747 }
4748 }
4749 st->cr();
4750#if INCLUDE_SERVICES
4751 if (print_concurrent_locks) {
4752 concurrent_locks.print_locks_on(p, st);
4753 }
4754#endif // INCLUDE_SERVICES
4755 }
4756
4757 VMThread::vm_thread()->print_on(st);
4758 st->cr();
4759 Universe::heap()->print_gc_threads_on(st);
4760 WatcherThread* wt = WatcherThread::watcher_thread();
4761 if (wt != NULL) {
4762 wt->print_on(st);
4763 st->cr();
4764 }
4765
4766 st->flush();
4767}
4768
4769void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
4770 int buflen, bool* found_current) {
4771 if (this_thread != NULL) {
4772 bool is_current = (current == this_thread);
4773 *found_current = *found_current || is_current;
4774 st->print("%s", is_current ? "=>" : " ");
4775
4776 st->print(PTR_FORMAT, p2i(this_thread));
4777 st->print(" ");
4778 this_thread->print_on_error(st, buf, buflen);
4779 st->cr();
4780 }
4781}
4782
4783class PrintOnErrorClosure : public ThreadClosure {
4784 outputStream* _st;
4785 Thread* _current;
4786 char* _buf;
4787 int _buflen;
4788 bool* _found_current;
4789 public:
4790 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf,
4791 int buflen, bool* found_current) :
4792 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {}
4793
4794 virtual void do_thread(Thread* thread) {
4795 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current);
4796 }
4797};
4798
4799// Threads::print_on_error() is called by fatal error handler. It's possible
4800// that VM is not at safepoint and/or current thread is inside signal handler.
4801// Don't print stack trace, as the stack may not be walkable. Don't allocate
4802// memory (even in resource area), it might deadlock the error handler.
4803void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4804 int buflen) {
4805 ThreadsSMRSupport::print_info_on(st);
4806 st->cr();
4807
4808 bool found_current = false;
4809 st->print_cr("Java Threads: ( => current thread )");
4810 ALL_JAVA_THREADS(thread) {
4811 print_on_error(thread, st, current, buf, buflen, &found_current);
4812 }
4813 st->cr();
4814
4815 st->print_cr("Other Threads:");
4816 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current);
4817 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current);
4818
4819 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current);
4820 Universe::heap()->gc_threads_do(&print_closure);
4821
4822 if (!found_current) {
4823 st->cr();
4824 st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
4825 current->print_on_error(st, buf, buflen);
4826 st->cr();
4827 }
4828 st->cr();
4829
4830 st->print_cr("Threads with active compile tasks:");
4831 print_threads_compiling(st, buf, buflen);
4832}
4833
4834void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) {
4835 ALL_JAVA_THREADS(thread) {
4836 if (thread->is_Compiler_thread()) {
4837 CompilerThread* ct = (CompilerThread*) thread;
4838
4839 // Keep task in local variable for NULL check.
4840 // ct->_task might be set to NULL by concurring compiler thread
4841 // because it completed the compilation. The task is never freed,
4842 // though, just returned to a free list.
4843 CompileTask* task = ct->task();
4844 if (task != NULL) {
4845 thread->print_name_on_error(st, buf, buflen);
4846 st->print(" ");
4847 task->print(st, NULL, short_form, true);
4848 }
4849 }
4850 }
4851}
4852
4853
4854// Internal SpinLock and Mutex
4855// Based on ParkEvent
4856
4857// Ad-hoc mutual exclusion primitives: SpinLock and Mux
4858//
4859// We employ SpinLocks _only for low-contention, fixed-length
4860// short-duration critical sections where we're concerned
4861// about native mutex_t or HotSpot Mutex:: latency.
4862// The mux construct provides a spin-then-block mutual exclusion
4863// mechanism.
4864//
4865// Testing has shown that contention on the ListLock guarding gFreeList
4866// is common. If we implement ListLock as a simple SpinLock it's common
4867// for the JVM to devolve to yielding with little progress. This is true
4868// despite the fact that the critical sections protected by ListLock are
4869// extremely short.
4870//
4871// TODO-FIXME: ListLock should be of type SpinLock.
4872// We should make this a 1st-class type, integrated into the lock
4873// hierarchy as leaf-locks. Critically, the SpinLock structure
4874// should have sufficient padding to avoid false-sharing and excessive
4875// cache-coherency traffic.
4876
4877
4878typedef volatile int SpinLockT;
4879
4880void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4881 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4882 return; // normal fast-path return
4883 }
4884
4885 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4886 int ctr = 0;
4887 int Yields = 0;
4888 for (;;) {
4889 while (*adr != 0) {
4890 ++ctr;
4891 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4892 if (Yields > 5) {
4893 os::naked_short_sleep(1);
4894 } else {
4895 os::naked_yield();
4896 ++Yields;
4897 }
4898 } else {
4899 SpinPause();
4900 }
4901 }
4902 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4903 }
4904}
4905
4906void Thread::SpinRelease(volatile int * adr) {
4907 assert(*adr != 0, "invariant");
4908 OrderAccess::fence(); // guarantee at least release consistency.
4909 // Roach-motel semantics.
4910 // It's safe if subsequent LDs and STs float "up" into the critical section,
4911 // but prior LDs and STs within the critical section can't be allowed
4912 // to reorder or float past the ST that releases the lock.
4913 // Loads and stores in the critical section - which appear in program
4914 // order before the store that releases the lock - must also appear
4915 // before the store that releases the lock in memory visibility order.
4916 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4917 // the ST of 0 into the lock-word which releases the lock, so fence
4918 // more than covers this on all platforms.
4919 *adr = 0;
4920}
4921
4922// muxAcquire and muxRelease:
4923//
4924// * muxAcquire and muxRelease support a single-word lock-word construct.
4925// The LSB of the word is set IFF the lock is held.
4926// The remainder of the word points to the head of a singly-linked list
4927// of threads blocked on the lock.
4928//
4929// * The current implementation of muxAcquire-muxRelease uses its own
4930// dedicated Thread._MuxEvent instance. If we're interested in
4931// minimizing the peak number of extant ParkEvent instances then
4932// we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4933// as certain invariants were satisfied. Specifically, care would need
4934// to be taken with regards to consuming unpark() "permits".
4935// A safe rule of thumb is that a thread would never call muxAcquire()
4936// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4937// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4938// consume an unpark() permit intended for monitorenter, for instance.
4939// One way around this would be to widen the restricted-range semaphore
4940// implemented in park(). Another alternative would be to provide
4941// multiple instances of the PlatformEvent() for each thread. One
4942// instance would be dedicated to muxAcquire-muxRelease, for instance.
4943//
4944// * Usage:
4945// -- Only as leaf locks
4946// -- for short-term locking only as muxAcquire does not perform
4947// thread state transitions.
4948//
4949// Alternatives:
4950// * We could implement muxAcquire and muxRelease with MCS or CLH locks
4951// but with parking or spin-then-park instead of pure spinning.
4952// * Use Taura-Oyama-Yonenzawa locks.
4953// * It's possible to construct a 1-0 lock if we encode the lockword as
4954// (List,LockByte). Acquire will CAS the full lockword while Release
4955// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4956// acquiring threads use timers (ParkTimed) to detect and recover from
4957// the stranding window. Thread/Node structures must be aligned on 256-byte
4958// boundaries by using placement-new.
4959// * Augment MCS with advisory back-link fields maintained with CAS().
4960// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4961// The validity of the backlinks must be ratified before we trust the value.
4962// If the backlinks are invalid the exiting thread must back-track through the
4963// the forward links, which are always trustworthy.
4964// * Add a successor indication. The LockWord is currently encoded as
4965// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4966// to provide the usual futile-wakeup optimization.
4967// See RTStt for details.
4968//
4969
4970
4971const intptr_t LOCKBIT = 1;
4972
4973void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4974 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
4975 if (w == 0) return;
4976 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4977 return;
4978 }
4979
4980 ParkEvent * const Self = Thread::current()->_MuxEvent;
4981 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4982 for (;;) {
4983 int its = (os::is_MP() ? 100 : 0) + 1;
4984
4985 // Optional spin phase: spin-then-park strategy
4986 while (--its >= 0) {
4987 w = *Lock;
4988 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
4989 return;
4990 }
4991 }
4992
4993 Self->reset();
4994 Self->OnList = intptr_t(Lock);
4995 // The following fence() isn't _strictly necessary as the subsequent
4996 // CAS() both serializes execution and ratifies the fetched *Lock value.
4997 OrderAccess::fence();
4998 for (;;) {
4999 w = *Lock;
5000 if ((w & LOCKBIT) == 0) {
5001 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5002 Self->OnList = 0; // hygiene - allows stronger asserts
5003 return;
5004 }
5005 continue; // Interference -- *Lock changed -- Just retry
5006 }
5007 assert(w & LOCKBIT, "invariant");
5008 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5009 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
5010 }
5011
5012 while (Self->OnList != 0) {
5013 Self->park();
5014 }
5015 }
5016}
5017
5018void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
5019 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0);
5020 if (w == 0) return;
5021 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5022 return;
5023 }
5024
5025 ParkEvent * ReleaseAfter = NULL;
5026 if (ev == NULL) {
5027 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
5028 }
5029 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
5030 for (;;) {
5031 guarantee(ev->OnList == 0, "invariant");
5032 int its = (os::is_MP() ? 100 : 0) + 1;
5033
5034 // Optional spin phase: spin-then-park strategy
5035 while (--its >= 0) {
5036 w = *Lock;
5037 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5038 if (ReleaseAfter != NULL) {
5039 ParkEvent::Release(ReleaseAfter);
5040 }
5041 return;
5042 }
5043 }
5044
5045 ev->reset();
5046 ev->OnList = intptr_t(Lock);
5047 // The following fence() isn't _strictly necessary as the subsequent
5048 // CAS() both serializes execution and ratifies the fetched *Lock value.
5049 OrderAccess::fence();
5050 for (;;) {
5051 w = *Lock;
5052 if ((w & LOCKBIT) == 0) {
5053 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) {
5054 ev->OnList = 0;
5055 // We call ::Release while holding the outer lock, thus
5056 // artificially lengthening the critical section.
5057 // Consider deferring the ::Release() until the subsequent unlock(),
5058 // after we've dropped the outer lock.
5059 if (ReleaseAfter != NULL) {
5060 ParkEvent::Release(ReleaseAfter);
5061 }
5062 return;
5063 }
5064 continue; // Interference -- *Lock changed -- Just retry
5065 }
5066 assert(w & LOCKBIT, "invariant");
5067 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
5068 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
5069 }
5070
5071 while (ev->OnList != 0) {
5072 ev->park();
5073 }
5074 }
5075}
5076
5077// Release() must extract a successor from the list and then wake that thread.
5078// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
5079// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
5080// Release() would :
5081// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
5082// (B) Extract a successor from the private list "in-hand"
5083// (C) attempt to CAS() the residual back into *Lock over null.
5084// If there were any newly arrived threads and the CAS() would fail.
5085// In that case Release() would detach the RATs, re-merge the list in-hand
5086// with the RATs and repeat as needed. Alternately, Release() might
5087// detach and extract a successor, but then pass the residual list to the wakee.
5088// The wakee would be responsible for reattaching and remerging before it
5089// competed for the lock.
5090//
5091// Both "pop" and DMR are immune from ABA corruption -- there can be
5092// multiple concurrent pushers, but only one popper or detacher.
5093// This implementation pops from the head of the list. This is unfair,
5094// but tends to provide excellent throughput as hot threads remain hot.
5095// (We wake recently run threads first).
5096//
5097// All paths through muxRelease() will execute a CAS.
5098// Release consistency -- We depend on the CAS in muxRelease() to provide full
5099// bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
5100// executed within the critical section are complete and globally visible before the
5101// store (CAS) to the lock-word that releases the lock becomes globally visible.
5102void Thread::muxRelease(volatile intptr_t * Lock) {
5103 for (;;) {
5104 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT);
5105 assert(w & LOCKBIT, "invariant");
5106 if (w == LOCKBIT) return;
5107 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
5108 assert(List != NULL, "invariant");
5109 assert(List->OnList == intptr_t(Lock), "invariant");
5110 ParkEvent * const nxt = List->ListNext;
5111 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
5112
5113 // The following CAS() releases the lock and pops the head element.
5114 // The CAS() also ratifies the previously fetched lock-word value.
5115 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) {
5116 continue;
5117 }
5118 List->OnList = 0;
5119 OrderAccess::fence();
5120 List->unpark();
5121 return;
5122 }
5123}
5124
5125
5126void Threads::verify() {
5127 ALL_JAVA_THREADS(p) {
5128 p->verify();
5129 }
5130 VMThread* thread = VMThread::vm_thread();
5131 if (thread != NULL) thread->verify();
5132}
5133