1 /*
2 * Copyright (c) 2005, 2012, 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_implementation/shared/vmGCOperations.hpp"
29 #include "memory/gcLocker.inline.hpp"
30 #include "memory/genCollectedHeap.hpp"
31 #include "memory/oopFactory.hpp"
32 #include "oops/instanceKlass.hpp"
33 #include "oops/instanceRefKlass.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/init.hpp"
36 #include "runtime/interfaceSupport.hpp"
37 #include "utilities/dtrace.hpp"
38 #include "utilities/preserveException.hpp"
39 #ifndef SERIALGC
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #endif
42
43 #ifndef USDT2
44 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
45 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
46 #endif /* !USDT2 */
47
48 // The same dtrace probe can't be inserted in two different files, so we
49 // have to call it here, so it's only in one file. Can't create new probes
50 // for the other file anymore. The dtrace probes have to remain stable.
51 void VM_GC_Operation::notify_gc_begin(bool full) {
52 #ifndef USDT2
53 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
54 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
55 #else /* USDT2 */
56 HOTSPOT_GC_BEGIN(
57 full);
58 #endif /* USDT2 */
59 }
60
61 void VM_GC_Operation::notify_gc_end() {
62 #ifndef USDT2
63 HS_DTRACE_PROBE(hotspot, gc__end);
64 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
65 #else /* USDT2 */
66 HOTSPOT_GC_END(
67 );
68 #endif /* USDT2 */
69 }
70
71 void VM_GC_Operation::acquire_pending_list_lock() {
72 // we may enter this with pending exception set
73 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
74 }
75
76
77 void VM_GC_Operation::release_and_notify_pending_list_lock() {
78
79 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
80 }
81
82 // Allocations may fail in several threads at about the same time,
83 // resulting in multiple gc requests. We only want to do one of them.
84 // In case a GC locker is active and the need for a GC is already signalled,
85 // we want to skip this GC attempt altogether, without doing a futile
86 // safepoint operation.
87 bool VM_GC_Operation::skip_operation() const {
88 bool skip = (_gc_count_before != Universe::heap()->total_collections());
89 if (_full && skip) {
90 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
91 }
92 if (!skip && GC_locker::is_active_and_needs_gc()) {
93 skip = Universe::heap()->is_maximal_no_gc();
94 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
95 "GC_locker cannot be active when initiating GC");
96 }
97 return skip;
98 }
99
100 bool VM_GC_Operation::doit_prologue() {
101 assert(Thread::current()->is_Java_thread(), "just checking");
102 assert(((_gc_cause != GCCause::_no_gc) &&
103 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
104
105 acquire_pending_list_lock();
106 // If the GC count has changed someone beat us to the collection
107 // Get the Heap_lock after the pending_list_lock.
108 Heap_lock->lock();
109
110 // Check invocations
111 if (skip_operation()) {
112 // skip collection
113 Heap_lock->unlock();
114 release_and_notify_pending_list_lock();
115 _prologue_succeeded = false;
116 } else {
117 _prologue_succeeded = true;
118 SharedHeap* sh = SharedHeap::heap();
119 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
120 }
121 return _prologue_succeeded;
122 }
123
124
125 void VM_GC_Operation::doit_epilogue() {
126 assert(Thread::current()->is_Java_thread(), "just checking");
127 // Release the Heap_lock first.
128 SharedHeap* sh = SharedHeap::heap();
129 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
130 Heap_lock->unlock();
131 release_and_notify_pending_list_lock();
132 }
133
134 bool VM_GC_HeapInspection::doit_prologue() {
135 if (Universe::heap()->supports_heap_inspection()) {
136 return VM_GC_Operation::doit_prologue();
137 } else {
138 return false;
139 }
140 }
141
142 bool VM_GC_HeapInspection::skip_operation() const {
143 assert(Universe::heap()->supports_heap_inspection(), "huh?");
144 return false;
145 }
146
147 void VM_GC_HeapInspection::doit() {
148 HandleMark hm;
149 CollectedHeap* ch = Universe::heap();
150 ch->ensure_parsability(false); // must happen, even if collection does
151 // not happen (e.g. due to GC_locker)
152 if (_full_gc) {
153 // The collection attempt below would be skipped anyway if
154 // the gc locker is held. The following dump may then be a tad
155 // misleading to someone expecting only live objects to show
156 // up in the dump (see CR 6944195). Just issue a suitable warning
157 // in that case and do not attempt to do a collection.
158 // The latter is a subtle point, because even a failed attempt
159 // to GC will, in fact, induce one in the future, which we
160 // probably want to avoid in this case because the GC that we may
161 // be about to attempt holds value for us only
162 // if it happens now and not if it happens in the eventual
163 // future.
164 if (GC_locker::is_active()) {
165 warning("GC locker is held; pre-dump GC was skipped");
166 } else {
167 ch->collect_as_vm_thread(GCCause::_heap_inspection);
168 }
169 }
170 HeapInspection::heap_inspection(_out, _need_prologue /* need_prologue */);
171 }
172
173
174 void VM_GenCollectForAllocation::doit() {
175 SvcGCMarker sgcm(SvcGCMarker::MINOR);
176
177 GenCollectedHeap* gch = GenCollectedHeap::heap();
178 GCCauseSetter gccs(gch, _gc_cause);
179 _res = gch->satisfy_failed_allocation(_size, _tlab);
180 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
181
182 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
183 set_gc_locked();
184 }
185 }
186
187 void VM_GenCollectFull::doit() {
188 SvcGCMarker sgcm(SvcGCMarker::FULL);
189
190 GenCollectedHeap* gch = GenCollectedHeap::heap();
191 GCCauseSetter gccs(gch, _gc_cause);
192 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
193 }
194
195 void VM_CollectForMetadataAllocation::doit() {
196 SvcGCMarker sgcm(SvcGCMarker::FULL);
197
198 CollectedHeap* heap = Universe::heap();
199 GCCauseSetter gccs(heap, _gc_cause);
200
201 // Check again if the space is available. Another thread
202 // may have similarly failed a metadata allocation and induced
203 // a GC that freed space for the allocation.
204 if (!MetadataAllocationFailALot) {
205 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
206 }
207
208 if (_result == NULL) {
209 if (UseConcMarkSweepGC) {
210 if (CMSClassUnloadingEnabled) {
211 MetaspaceGC::set_should_concurrent_collect(true);
212 }
213 // For CMS expand since the collection is going to be concurrent.
214 _result =
215 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
216 }
217 if (_result == NULL) {
218 // Don't clear the soft refs. This GC is for reclaiming metadata
219 // and is unrelated to the fullness of the Java heap which should
220 // be the criteria for clearing SoftReferences.
221 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) {
222 gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
223 }
224 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
225 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
226 }
227 if (_result == NULL && !UseConcMarkSweepGC /* CMS already tried */) {
228 // If still failing, allow the Metaspace to expand.
229 // See delta_capacity_until_GC() for explanation of the
230 // amount of the expansion.
231 // This should work unless there really is no more space
232 // or a MaxMetaspaceSize has been specified on the command line.
233 _result =
234 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
235
236 }
237 if (Verbose && PrintGCDetails && _result == NULL) {
238 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
239 SIZE_FORMAT, _size);
240 }
241 }
242
243 if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
244 set_gc_locked();
245 }
246 }