1 /*
2 * Copyright (c) 2005, 2017, 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.inline.hpp"
31 #include "gc/shared/genCollectedHeap.hpp"
32 #include "gc/shared/softRefPolicy.hpp"
33 #include "gc/shared/vmGCOperations.hpp"
34 #include "interpreter/oopMapCache.hpp"
35 #include "logging/log.hpp"
36 #include "memory/oopFactory.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "runtime/init.hpp"
39 #include "runtime/interfaceSupport.hpp"
40 #include "utilities/dtrace.hpp"
41 #include "utilities/macros.hpp"
42 #include "utilities/preserveException.hpp"
43 #if INCLUDE_ALL_GCS
44 #include "gc/g1/g1CollectedHeap.inline.hpp"
45 #include "gc/g1/g1Policy.hpp"
46 #endif // INCLUDE_ALL_GCS
47
48 VM_GC_Operation::~VM_GC_Operation() {
49 CollectedHeap* ch = Universe::heap();
50 ch->soft_ref_policy()->set_all_soft_refs_clear(false);
51 }
52
53 // The same dtrace probe can't be inserted in two different files, so we
54 // have to call it here, so it's only in one file. Can't create new probes
55 // for the other file anymore. The dtrace probes have to remain stable.
56 void VM_GC_Operation::notify_gc_begin(bool full) {
57 HOTSPOT_GC_BEGIN(
58 full);
59 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
60 }
61
62 void VM_GC_Operation::notify_gc_end() {
63 HOTSPOT_GC_END();
64 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
65 }
66
67 // Allocations may fail in several threads at about the same time,
68 // resulting in multiple gc requests. We only want to do one of them.
69 // In case a GC locker is active and the need for a GC is already signaled,
70 // we want to skip this GC attempt altogether, without doing a futile
71 // safepoint operation.
72 bool VM_GC_Operation::skip_operation() const {
73 bool skip = (_gc_count_before != Universe::heap()->total_collections());
74 if (_full && skip) {
75 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
76 }
77 if (!skip && GCLocker::is_active_and_needs_gc()) {
78 skip = Universe::heap()->is_maximal_no_gc();
79 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
80 "GCLocker cannot be active when initiating GC");
81 }
82 return skip;
83 }
84
85 bool VM_GC_Operation::doit_prologue() {
86 assert(Thread::current()->is_Java_thread(), "just checking");
87 assert(((_gc_cause != GCCause::_no_gc) &&
88 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
89
90 // To be able to handle a GC the VM initialization needs to be completed.
91 if (!is_init_completed()) {
92 vm_exit_during_initialization(
93 err_msg("GC triggered before VM initialization completed. Try increasing "
94 "NewSize, current value " SIZE_FORMAT "%s.",
95 byte_size_in_proper_unit(NewSize),
96 proper_unit_for_byte_size(NewSize)));
97 }
98
99 // If the GC count has changed someone beat us to the collection
100 Heap_lock->lock();
101
102 // Check invocations
103 if (skip_operation()) {
104 // skip collection
105 Heap_lock->unlock();
106 _prologue_succeeded = false;
107 } else {
108 _prologue_succeeded = true;
109 }
110 return _prologue_succeeded;
111 }
112
113
114 void VM_GC_Operation::doit_epilogue() {
115 assert(Thread::current()->is_Java_thread(), "just checking");
116 // Clean up old interpreter OopMap entries that were replaced
117 // during the GC thread root traversal.
118 OopMapCache::cleanup_old_entries();
119 if (Universe::has_reference_pending_list()) {
120 Heap_lock->notify_all();
121 }
122 Heap_lock->unlock();
123 }
124
125 bool VM_GC_HeapInspection::skip_operation() const {
126 return false;
127 }
128
129 bool VM_GC_HeapInspection::collect() {
130 if (GCLocker::is_active()) {
131 return false;
132 }
133 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
134 return true;
135 }
136
137 void VM_GC_HeapInspection::doit() {
138 HandleMark hm;
139 Universe::heap()->ensure_parsability(false); // must happen, even if collection does
140 // not happen (e.g. due to GCLocker)
141 // or _full_gc being false
142 if (_full_gc) {
143 if (!collect()) {
144 // The collection attempt was skipped because the gc locker is held.
145 // The following dump may then be a tad misleading to someone expecting
146 // only live objects to show up in the dump (see CR 6944195). Just issue
147 // a suitable warning in that case and do not attempt to do a collection.
148 // The latter is a subtle point, because even a failed attempt
149 // to GC will, in fact, induce one in the future, which we
150 // probably want to avoid in this case because the GC that we may
151 // be about to attempt holds value for us only
152 // if it happens now and not if it happens in the eventual
153 // future.
154 log_warning(gc)("GC locker is held; pre-dump GC was skipped");
155 }
156 }
157 HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
158 _columns);
159 inspect.heap_inspection(_out);
160 }
161
162
163 void VM_GenCollectForAllocation::doit() {
164 SvcGCMarker sgcm(SvcGCMarker::MINOR);
165
166 GenCollectedHeap* gch = GenCollectedHeap::heap();
167 GCCauseSetter gccs(gch, _gc_cause);
168 _result = gch->satisfy_failed_allocation(_word_size, _tlab);
169 assert(gch->is_in_reserved_or_null(_result), "result not in heap");
170
171 if (_result == NULL && GCLocker::is_active_and_needs_gc()) {
172 set_gc_locked();
173 }
174 }
175
176 void VM_GenCollectFull::doit() {
177 SvcGCMarker sgcm(SvcGCMarker::FULL);
178
179 GenCollectedHeap* gch = GenCollectedHeap::heap();
180 GCCauseSetter gccs(gch, _gc_cause);
181 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation);
182 }
183
184 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data,
185 size_t size,
186 Metaspace::MetadataType mdtype,
187 uint gc_count_before,
188 uint full_gc_count_before,
189 GCCause::Cause gc_cause)
190 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
191 _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) {
192 assert(_size != 0, "An allocation should always be requested with this operation.");
193 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek());
194 }
195
196 // Returns true iff concurrent GCs unloads metadata.
197 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {
198 #if INCLUDE_ALL_GCS
199 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {
200 MetaspaceGC::set_should_concurrent_collect(true);
201 return true;
202 }
203
204 if (UseG1GC && ClassUnloadingWithConcurrentMark) {
205 G1CollectedHeap* g1h = G1CollectedHeap::heap();
206 g1h->g1_policy()->collector_state()->set_initiate_conc_mark_if_possible(true);
207
208 GCCauseSetter x(g1h, _gc_cause);
209
210 // At this point we are supposed to start a concurrent cycle. We
211 // will do so if one is not already in progress.
212 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
213
214 if (should_start) {
215 double pause_target = g1h->g1_policy()->max_pause_time_ms();
216 g1h->do_collection_pause_at_safepoint(pause_target);
217 }
218 return true;
219 }
220 #endif
221
222 return false;
223 }
224
225 void VM_CollectForMetadataAllocation::doit() {
226 SvcGCMarker sgcm(SvcGCMarker::FULL);
227
228 CollectedHeap* heap = Universe::heap();
229 GCCauseSetter gccs(heap, _gc_cause);
230
231 // Check again if the space is available. Another thread
232 // may have similarly failed a metadata allocation and induced
233 // a GC that freed space for the allocation.
234 if (!MetadataAllocationFailALot) {
235 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
236 if (_result != NULL) {
237 return;
238 }
239 }
240
241 if (initiate_concurrent_GC()) {
242 // For CMS and G1 expand since the collection is going to be concurrent.
243 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
244 if (_result != NULL) {
245 return;
246 }
247
248 log_debug(gc)("%s full GC for Metaspace", UseConcMarkSweepGC ? "CMS" : "G1");
249 }
250
251 // Don't clear the soft refs yet.
252 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
253 // After a GC try to allocate without expanding. Could fail
254 // and expansion will be tried below.
255 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
256 if (_result != NULL) {
257 return;
258 }
259
260 // If still failing, allow the Metaspace to expand.
261 // See delta_capacity_until_GC() for explanation of the
262 // amount of the expansion.
263 // This should work unless there really is no more space
264 // or a MaxMetaspaceSize has been specified on the command line.
265 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
266 if (_result != NULL) {
267 return;
268 }
269
270 // If expansion failed, do a collection clearing soft references.
271 heap->collect_as_vm_thread(GCCause::_metadata_GC_clear_soft_refs);
272 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
273 if (_result != NULL) {
274 return;
275 }
276
277 log_debug(gc)("After Metaspace GC failed to allocate size " SIZE_FORMAT, _size);
278
279 if (GCLocker::is_active_and_needs_gc()) {
280 set_gc_locked();
281 }
282 }
283
284 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
285 : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) {
286 // Only report if operation was really caused by an allocation.
287 if (_word_size != 0) {
288 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek());
289 }
290 }