1/*
2 * Copyright (c) 2005, 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 "classfile/classLoader.hpp"
27#include "classfile/javaClasses.hpp"
28#include "gc/shared/allocTracer.hpp"
29#include "gc/shared/gcId.hpp"
30#include "gc/shared/gcLocker.hpp"
31#include "gc/shared/gcVMOperations.hpp"
32#include "gc/shared/genCollectedHeap.hpp"
33#include "interpreter/oopMapCache.hpp"
34#include "logging/log.hpp"
35#include "memory/oopFactory.hpp"
36#include "memory/universe.hpp"
37#include "runtime/handles.inline.hpp"
38#include "runtime/init.hpp"
39#include "utilities/dtrace.hpp"
40#include "utilities/macros.hpp"
41#include "utilities/preserveException.hpp"
42#if INCLUDE_G1GC
43#include "gc/g1/g1CollectedHeap.inline.hpp"
44#include "gc/g1/g1Policy.hpp"
45#endif // INCLUDE_G1GC
46
47VM_GC_Operation::~VM_GC_Operation() {
48 CollectedHeap* ch = Universe::heap();
49 ch->soft_ref_policy()->set_all_soft_refs_clear(false);
50}
51
52// The same dtrace probe can't be inserted in two different files, so we
53// have to call it here, so it's only in one file. Can't create new probes
54// for the other file anymore. The dtrace probes have to remain stable.
55void VM_GC_Operation::notify_gc_begin(bool full) {
56 HOTSPOT_GC_BEGIN(
57 full);
58 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
59}
60
61void VM_GC_Operation::notify_gc_end() {
62 HOTSPOT_GC_END();
63 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
64}
65
66// Allocations may fail in several threads at about the same time,
67// resulting in multiple gc requests. We only want to do one of them.
68// In case a GC locker is active and the need for a GC is already signaled,
69// we want to skip this GC attempt altogether, without doing a futile
70// safepoint operation.
71bool VM_GC_Operation::skip_operation() const {
72 bool skip = (_gc_count_before != Universe::heap()->total_collections());
73 if (_full && skip) {
74 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
75 }
76 if (!skip && GCLocker::is_active_and_needs_gc()) {
77 skip = Universe::heap()->is_maximal_no_gc();
78 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
79 "GCLocker cannot be active when initiating GC");
80 }
81 return skip;
82}
83
84bool VM_GC_Operation::doit_prologue() {
85 assert(((_gc_cause != GCCause::_no_gc) &&
86 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
87
88 // To be able to handle a GC the VM initialization needs to be completed.
89 if (!is_init_completed()) {
90 vm_exit_during_initialization(
91 err_msg("GC triggered before VM initialization completed. Try increasing "
92 "NewSize, current value " SIZE_FORMAT "%s.",
93 byte_size_in_proper_unit(NewSize),
94 proper_unit_for_byte_size(NewSize)));
95 }
96
97 // If the GC count has changed someone beat us to the collection
98 Heap_lock->lock();
99
100 // Check invocations
101 if (skip_operation()) {
102 // skip collection
103 Heap_lock->unlock();
104 _prologue_succeeded = false;
105 } else {
106 _prologue_succeeded = true;
107 }
108 return _prologue_succeeded;
109}
110
111
112void VM_GC_Operation::doit_epilogue() {
113 // Clean up old interpreter OopMap entries that were replaced
114 // during the GC thread root traversal.
115 OopMapCache::cleanup_old_entries();
116 if (Universe::has_reference_pending_list()) {
117 Heap_lock->notify_all();
118 }
119 Heap_lock->unlock();
120}
121
122bool VM_GC_HeapInspection::skip_operation() const {
123 return false;
124}
125
126bool VM_GC_HeapInspection::collect() {
127 if (GCLocker::is_active()) {
128 return false;
129 }
130 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
131 return true;
132}
133
134void VM_GC_HeapInspection::doit() {
135 HandleMark hm;
136 Universe::heap()->ensure_parsability(false); // must happen, even if collection does
137 // not happen (e.g. due to GCLocker)
138 // or _full_gc being false
139 if (_full_gc) {
140 if (!collect()) {
141 // The collection attempt was skipped because the gc locker is held.
142 // The following dump may then be a tad misleading to someone expecting
143 // only live objects to show up in the dump (see CR 6944195). Just issue
144 // a suitable warning in that case and do not attempt to do a collection.
145 // The latter is a subtle point, because even a failed attempt
146 // to GC will, in fact, induce one in the future, which we
147 // probably want to avoid in this case because the GC that we may
148 // be about to attempt holds value for us only
149 // if it happens now and not if it happens in the eventual
150 // future.
151 log_warning(gc)("GC locker is held; pre-dump GC was skipped");
152 }
153 }
154 HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
155 _columns);
156 inspect.heap_inspection(_out);
157}
158
159
160void VM_GenCollectForAllocation::doit() {
161 SvcGCMarker sgcm(SvcGCMarker::MINOR);
162
163 GenCollectedHeap* gch = GenCollectedHeap::heap();
164 GCCauseSetter gccs(gch, _gc_cause);
165 _result = gch->satisfy_failed_allocation(_word_size, _tlab);
166 assert(gch->is_in_reserved_or_null(_result), "result not in heap");
167
168 if (_result == NULL && GCLocker::is_active_and_needs_gc()) {
169 set_gc_locked();
170 }
171}
172
173void VM_GenCollectFull::doit() {
174 SvcGCMarker sgcm(SvcGCMarker::FULL);
175
176 GenCollectedHeap* gch = GenCollectedHeap::heap();
177 GCCauseSetter gccs(gch, _gc_cause);
178 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation);
179}
180
181VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data,
182 size_t size,
183 Metaspace::MetadataType mdtype,
184 uint gc_count_before,
185 uint full_gc_count_before,
186 GCCause::Cause gc_cause)
187 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
188 _result(NULL), _size(size), _mdtype(mdtype), _loader_data(loader_data) {
189 assert(_size != 0, "An allocation should always be requested with this operation.");
190 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek());
191}
192
193// Returns true iff concurrent GCs unloads metadata.
194bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {
195#if INCLUDE_CMSGC
196 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {
197 MetaspaceGC::set_should_concurrent_collect(true);
198 return true;
199 }
200#endif
201
202#if INCLUDE_G1GC
203 if (UseG1GC && ClassUnloadingWithConcurrentMark) {
204 G1CollectedHeap* g1h = G1CollectedHeap::heap();
205 g1h->policy()->collector_state()->set_initiate_conc_mark_if_possible(true);
206
207 GCCauseSetter x(g1h, _gc_cause);
208
209 // At this point we are supposed to start a concurrent cycle. We
210 // will do so if one is not already in progress.
211 bool should_start = g1h->policy()->force_initial_mark_if_outside_cycle(_gc_cause);
212
213 if (should_start) {
214 double pause_target = g1h->policy()->max_pause_time_ms();
215 g1h->do_collection_pause_at_safepoint(pause_target);
216 }
217 return true;
218 }
219#endif
220
221 return false;
222}
223
224void VM_CollectForMetadataAllocation::doit() {
225 SvcGCMarker sgcm(SvcGCMarker::FULL);
226
227 CollectedHeap* heap = Universe::heap();
228 GCCauseSetter gccs(heap, _gc_cause);
229
230 // Check again if the space is available. Another thread
231 // may have similarly failed a metadata allocation and induced
232 // a GC that freed space for the allocation.
233 if (!MetadataAllocationFailALot) {
234 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
235 if (_result != NULL) {
236 return;
237 }
238 }
239
240 if (initiate_concurrent_GC()) {
241 // For CMS and G1 expand since the collection is going to be concurrent.
242 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
243 if (_result != NULL) {
244 return;
245 }
246
247 log_debug(gc)("%s full GC for Metaspace", UseConcMarkSweepGC ? "CMS" : "G1");
248 }
249
250 // Don't clear the soft refs yet.
251 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
252 // After a GC try to allocate without expanding. Could fail
253 // and expansion will be tried below.
254 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
255 if (_result != NULL) {
256 return;
257 }
258
259 // If still failing, allow the Metaspace to expand.
260 // See delta_capacity_until_GC() for explanation of the
261 // amount of the expansion.
262 // This should work unless there really is no more space
263 // or a MaxMetaspaceSize has been specified on the command line.
264 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
265 if (_result != NULL) {
266 return;
267 }
268
269 // If expansion failed, do a collection clearing soft references.
270 heap->collect_as_vm_thread(GCCause::_metadata_GC_clear_soft_refs);
271 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
272 if (_result != NULL) {
273 return;
274 }
275
276 log_debug(gc)("After Metaspace GC failed to allocate size " SIZE_FORMAT, _size);
277
278 if (GCLocker::is_active_and_needs_gc()) {
279 set_gc_locked();
280 }
281}
282
283VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
284 : VM_GC_Operation(gc_count_before, cause), _word_size(word_size), _result(NULL) {
285 // Only report if operation was really caused by an allocation.
286 if (_word_size != 0) {
287 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek());
288 }
289}
290