1 /*
2 * Copyright (c) 2005, 2015, 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 "memory/oopFactory.hpp"
34 #include "oops/instanceKlass.hpp"
35 #include "oops/instanceRefKlass.hpp"
36 #include "runtime/handles.inline.hpp"
37 #include "runtime/init.hpp"
38 #include "runtime/interfaceSupport.hpp"
39 #include "utilities/dtrace.hpp"
40 #include "utilities/macros.hpp"
41 #include "utilities/preserveException.hpp"
42 #if INCLUDE_ALL_GCS
43 #include "gc/g1/g1CollectedHeap.inline.hpp"
44 #endif // INCLUDE_ALL_GCS
45
46 VM_GC_Operation::~VM_GC_Operation() {
47 CollectedHeap* ch = Universe::heap();
48 ch->collector_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 void VM_GC_Operation::acquire_pending_list_lock() {
66 // we may enter this with pending exception set
67 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
68 }
69
70
71 void VM_GC_Operation::release_and_notify_pending_list_lock() {
72
73 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
74 }
75
76 // Allocations may fail in several threads at about the same time,
77 // resulting in multiple gc requests. We only want to do one of them.
78 // In case a GC locker is active and the need for a GC is already signaled,
79 // we want to skip this GC attempt altogether, without doing a futile
80 // safepoint operation.
81 bool VM_GC_Operation::skip_operation() const {
82 bool skip = (_gc_count_before != Universe::heap()->total_collections());
83 if (_full && skip) {
84 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
85 }
86 if (!skip && GC_locker::is_active_and_needs_gc()) {
87 skip = Universe::heap()->is_maximal_no_gc();
88 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
89 "GC_locker cannot be active when initiating GC");
90 }
91 return skip;
92 }
93
94 bool VM_GC_Operation::doit_prologue() {
95 assert(Thread::current()->is_Java_thread(), "just checking");
96 assert(((_gc_cause != GCCause::_no_gc) &&
97 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
98
99 // To be able to handle a GC the VM initialization needs to be completed.
100 if (!is_init_completed()) {
101 vm_exit_during_initialization(
102 err_msg("GC triggered before VM initialization completed. Try increasing "
103 "NewSize, current value " SIZE_FORMAT "%s.",
104 byte_size_in_proper_unit(NewSize),
105 proper_unit_for_byte_size(NewSize)));
106 }
107
108 acquire_pending_list_lock();
109 // If the GC count has changed someone beat us to the collection
110 // Get the Heap_lock after the pending_list_lock.
111 Heap_lock->lock();
112
113 // Check invocations
114 if (skip_operation()) {
115 // skip collection
116 Heap_lock->unlock();
117 release_and_notify_pending_list_lock();
118 _prologue_succeeded = false;
119 } else {
120 _prologue_succeeded = true;
121 }
122 return _prologue_succeeded;
123 }
124
125
126 void VM_GC_Operation::doit_epilogue() {
127 assert(Thread::current()->is_Java_thread(), "just checking");
128 // Release the Heap_lock first.
129 Heap_lock->unlock();
130 release_and_notify_pending_list_lock();
131 }
132
133 bool VM_GC_HeapInspection::skip_operation() const {
134 return false;
135 }
136
137 bool VM_GC_HeapInspection::collect() {
138 if (GC_locker::is_active()) {
139 return false;
140 }
141 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
142 return true;
143 }
144
145 void VM_GC_HeapInspection::doit() {
146 HandleMark hm;
147 Universe::heap()->ensure_parsability(false); // must happen, even if collection does
148 // not happen (e.g. due to GC_locker)
149 // or _full_gc being false
150 if (_full_gc) {
151 if (!collect()) {
152 // The collection attempt was skipped because the gc locker is held.
153 // The following dump may then be a tad misleading to someone expecting
154 // only live objects to show up in the dump (see CR 6944195). Just issue
155 // a suitable warning in that case and do not attempt to do a collection.
156 // The latter is a subtle point, because even a failed attempt
157 // to GC will, in fact, induce one in the future, which we
158 // probably want to avoid in this case because the GC that we may
159 // be about to attempt holds value for us only
160 // if it happens now and not if it happens in the eventual
161 // future.
162 warning("GC locker is held; pre-dump GC was skipped");
163 }
164 }
165 HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
166 _columns);
167 inspect.heap_inspection(_out);
168 }
169
170
171 void VM_GenCollectForAllocation::doit() {
172 SvcGCMarker sgcm(SvcGCMarker::MINOR);
173
174 GenCollectedHeap* gch = GenCollectedHeap::heap();
175 GCCauseSetter gccs(gch, _gc_cause);
176 _result = gch->satisfy_failed_allocation(_word_size, _tlab);
177 assert(gch->is_in_reserved_or_null(_result), "result not in heap");
178
179 if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
180 set_gc_locked();
181 }
182 }
183
184 void VM_GenCollectFull::doit() {
185 SvcGCMarker sgcm(SvcGCMarker::FULL);
186
187 GenCollectedHeap* gch = GenCollectedHeap::heap();
188 GCCauseSetter gccs(gch, _gc_cause);
189 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_generation);
190 }
191
192 VM_CollectForMetadataAllocation::VM_CollectForMetadataAllocation(ClassLoaderData* loader_data,
193 size_t size,
194 Metaspace::MetadataType mdtype,
195 uint gc_count_before,
196 uint full_gc_count_before,
197 GCCause::Cause gc_cause)
198 : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true),
199 _loader_data(loader_data), _size(size), _mdtype(mdtype), _result(NULL) {
200 assert(_size != 0, "An allocation should always be requested with this operation.");
201 AllocTracer::send_allocation_requiring_gc_event(_size * HeapWordSize, GCId::peek());
202 }
203
204 // Returns true iff concurrent GCs unloads metadata.
205 bool VM_CollectForMetadataAllocation::initiate_concurrent_GC() {
206 #if INCLUDE_ALL_GCS
207 if (UseConcMarkSweepGC && CMSClassUnloadingEnabled) {
208 MetaspaceGC::set_should_concurrent_collect(true);
209 return true;
210 }
211
212 if (UseG1GC && ClassUnloadingWithConcurrentMark) {
213 G1CollectedHeap* g1h = G1CollectedHeap::heap();
214 g1h->g1_policy()->collector_state()->set_initiate_conc_mark_if_possible(true);
215
216 GCCauseSetter x(g1h, _gc_cause);
217
218 // At this point we are supposed to start a concurrent cycle. We
219 // will do so if one is not already in progress.
220 bool should_start = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
221
222 if (should_start) {
223 double pause_target = g1h->g1_policy()->max_pause_time_ms();
224 g1h->do_collection_pause_at_safepoint(pause_target);
225 }
226 return true;
227 }
228 #endif
229
230 return false;
231 }
232
233 static void log_metaspace_alloc_failure_for_concurrent_GC() {
234 if (Verbose && PrintGCDetails) {
235 if (UseConcMarkSweepGC) {
236 gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
237 } else if (UseG1GC) {
238 gclog_or_tty->print_cr("\nG1 full GC for Metaspace");
239 }
240 }
241 }
242
243 void VM_CollectForMetadataAllocation::doit() {
244 SvcGCMarker sgcm(SvcGCMarker::FULL);
245
246 CollectedHeap* heap = Universe::heap();
247 GCCauseSetter gccs(heap, _gc_cause);
248
249 // Check again if the space is available. Another thread
250 // may have similarly failed a metadata allocation and induced
251 // a GC that freed space for the allocation.
252 if (!MetadataAllocationFailALot) {
253 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
254 if (_result != NULL) {
255 return;
256 }
257 }
258
259 if (initiate_concurrent_GC()) {
260 // For CMS and G1 expand since the collection is going to be concurrent.
261 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
262 if (_result != NULL) {
263 return;
264 }
265
266 log_metaspace_alloc_failure_for_concurrent_GC();
267 }
268
269 // Don't clear the soft refs yet.
270 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
271 // After a GC try to allocate without expanding. Could fail
272 // and expansion will be tried below.
273 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
274 if (_result != NULL) {
275 return;
276 }
277
278 // If still failing, allow the Metaspace to expand.
279 // See delta_capacity_until_GC() for explanation of the
280 // amount of the expansion.
281 // This should work unless there really is no more space
282 // or a MaxMetaspaceSize has been specified on the command line.
283 _result = _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
284 if (_result != NULL) {
285 return;
286 }
287
288 // If expansion failed, do a last-ditch collection and try allocating
289 // again. A last-ditch collection will clear softrefs. This
290 // behavior is similar to the last-ditch collection done for perm
291 // gen when it was full and a collection for failed allocation
292 // did not free perm gen space.
293 heap->collect_as_vm_thread(GCCause::_last_ditch_collection);
294 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
295 if (_result != NULL) {
296 return;
297 }
298
299 if (Verbose && PrintGCDetails) {
300 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
301 SIZE_FORMAT, _size);
302 }
303
304 if (GC_locker::is_active_and_needs_gc()) {
305 set_gc_locked();
306 }
307 }
308
309 VM_CollectForAllocation::VM_CollectForAllocation(size_t word_size, uint gc_count_before, GCCause::Cause cause)
310 : VM_GC_Operation(gc_count_before, cause), _result(NULL), _word_size(word_size) {
311 // Only report if operation was really caused by an allocation.
312 if (_word_size != 0) {
313 AllocTracer::send_allocation_requiring_gc_event(_word_size * HeapWordSize, GCId::peek());
314 }
315 }