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