1 /*
2 * Copyright (c) 2005, 2013, 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 #include "utilities/macros.hpp"
40 #if INCLUDE_ALL_GCS
41 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
42 #endif // INCLUDE_ALL_GCS
43
44 #ifndef USDT2
45 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
46 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
47 #endif /* !USDT2 */
48
49 // The same dtrace probe can't be inserted in two different files, so we
50 // have to call it here, so it's only in one file. Can't create new probes
51 // for the other file anymore. The dtrace probes have to remain stable.
52 void VM_GC_Operation::notify_gc_begin(bool full) {
53 #ifndef USDT2
54 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
55 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
56 #else /* USDT2 */
57 HOTSPOT_GC_BEGIN(
58 full);
59 #endif /* USDT2 */
60 }
61
62 void VM_GC_Operation::notify_gc_end() {
63 #ifndef USDT2
64 HS_DTRACE_PROBE(hotspot, gc__end);
65 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
66 #else /* USDT2 */
67 HOTSPOT_GC_END(
68 );
69 #endif /* USDT2 */
70 }
71
72 void VM_GC_Operation::acquire_pending_list_lock() {
73 // we may enter this with pending exception set
74 InstanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
75 }
76
77
78 void VM_GC_Operation::release_and_notify_pending_list_lock() {
79
80 InstanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
81 }
82
83 // Allocations may fail in several threads at about the same time,
84 // resulting in multiple gc requests. We only want to do one of them.
85 // In case a GC locker is active and the need for a GC is already signaled,
86 // we want to skip this GC attempt altogether, without doing a futile
87 // safepoint operation.
88 bool VM_GC_Operation::skip_operation() const {
89 bool skip = (_gc_count_before != Universe::heap()->total_collections());
90 if (_full && skip) {
91 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
92 }
93 if (!skip && GC_locker::is_active_and_needs_gc()) {
94 skip = Universe::heap()->is_maximal_no_gc();
95 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
96 "GC_locker cannot be active when initiating GC");
97 }
98 return skip;
99 }
100
101 bool VM_GC_Operation::doit_prologue() {
102 assert(Thread::current()->is_Java_thread(), "just checking");
103 assert(((_gc_cause != GCCause::_no_gc) &&
104 (_gc_cause != GCCause::_no_cause_specified)), "Illegal GCCause");
105
106 acquire_pending_list_lock();
107 // If the GC count has changed someone beat us to the collection
108 // Get the Heap_lock after the pending_list_lock.
109 Heap_lock->lock();
110
111 // Check invocations
112 if (skip_operation()) {
113 // skip collection
114 Heap_lock->unlock();
115 release_and_notify_pending_list_lock();
116 _prologue_succeeded = false;
117 } else {
118 _prologue_succeeded = true;
119 SharedHeap* sh = SharedHeap::heap();
120 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = 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 SharedHeap* sh = SharedHeap::heap();
130 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
131 Heap_lock->unlock();
132 release_and_notify_pending_list_lock();
133 }
134
135 bool VM_GC_HeapInspection::doit_prologue() {
136 if (Universe::heap()->supports_heap_inspection()) {
137 return VM_GC_Operation::doit_prologue();
138 } else {
139 return false;
140 }
141 }
142
143 bool VM_GC_HeapInspection::skip_operation() const {
144 assert(Universe::heap()->supports_heap_inspection(), "huh?");
145 return false;
146 }
147
148 bool VM_GC_HeapInspection::collect() {
149 if (GC_locker::is_active()) {
150 return false;
151 }
152 Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
153 return true;
154 }
155
156 void VM_GC_HeapInspection::doit() {
157 HandleMark hm;
158 Universe::heap()->ensure_parsability(false); // must happen, even if collection does
159 // not happen (e.g. due to GC_locker)
160 // or _full_gc being false
161 if (_full_gc) {
162 if (!collect()) {
163 // The collection attempt was skipped because the gc locker is held.
164 // The following dump may then be a tad misleading to someone expecting
165 // only live objects to show up in the dump (see CR 6944195). Just issue
166 // a suitable warning in that case and do not attempt to do a collection.
167 // The latter is a subtle point, because even a failed attempt
168 // to GC will, in fact, induce one in the future, which we
169 // probably want to avoid in this case because the GC that we may
170 // be about to attempt holds value for us only
171 // if it happens now and not if it happens in the eventual
172 // future.
173 warning("GC locker is held; pre-dump GC was skipped");
174 }
175 }
176 HeapInspection inspect(_csv_format, _print_help, _print_class_stats,
177 _columns);
178 inspect.heap_inspection(_out);
179 }
180
181
182 void VM_GenCollectForAllocation::doit() {
183 SvcGCMarker sgcm(SvcGCMarker::MINOR);
184
185 GenCollectedHeap* gch = GenCollectedHeap::heap();
186 GCCauseSetter gccs(gch, _gc_cause);
187 _res = gch->satisfy_failed_allocation(_size, _tlab);
188 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
189
190 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
191 set_gc_locked();
192 }
193 }
194
195 void VM_GenCollectFull::doit() {
196 SvcGCMarker sgcm(SvcGCMarker::FULL);
197
198 GenCollectedHeap* gch = GenCollectedHeap::heap();
199 GCCauseSetter gccs(gch, _gc_cause);
200 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
201 }
202
203 void VM_CollectForMetadataAllocation::doit() {
204 SvcGCMarker sgcm(SvcGCMarker::FULL);
205
206 CollectedHeap* heap = Universe::heap();
207 GCCauseSetter gccs(heap, _gc_cause);
208
209 // Check again if the space is available. Another thread
210 // may have similarly failed a metadata allocation and induced
211 // a GC that freed space for the allocation.
212 if (!MetadataAllocationFailALot) {
213 _result = _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
214 }
215
216 if (_result == NULL) {
217 if (UseConcMarkSweepGC) {
218 if (CMSClassUnloadingEnabled) {
219 MetaspaceGC::set_should_concurrent_collect(true);
220 }
221 // For CMS expand since the collection is going to be concurrent.
222 _result =
223 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
224 }
225 if (_result == NULL) {
226 // Don't clear the soft refs yet.
227 if (Verbose && PrintGCDetails && UseConcMarkSweepGC) {
228 gclog_or_tty->print_cr("\nCMS full GC for Metaspace");
229 }
230 heap->collect_as_vm_thread(GCCause::_metadata_GC_threshold);
231 // After a GC try to allocate without expanding. Could fail
232 // and expansion will be tried below.
233 _result =
234 _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
235 }
236 if (_result == NULL) {
237 // If still failing, allow the Metaspace to expand.
238 // See delta_capacity_until_GC() for explanation of the
239 // amount of the expansion.
240 // This should work unless there really is no more space
241 // or a MaxMetaspaceSize has been specified on the command line.
242 _result =
243 _loader_data->metaspace_non_null()->expand_and_allocate(_size, _mdtype);
244 if (_result == NULL) {
245 // If expansion failed, do a last-ditch collection and try allocating
246 // again. A last-ditch collection will clear softrefs. This
247 // behavior is similar to the last-ditch collection done for perm
248 // gen when it was full and a collection for failed allocation
249 // did not free perm gen space.
250 heap->collect_as_vm_thread(GCCause::_last_ditch_collection);
251 _result =
252 _loader_data->metaspace_non_null()->allocate(_size, _mdtype);
253 }
254 }
255 if (Verbose && PrintGCDetails && _result == NULL) {
256 gclog_or_tty->print_cr("\nAfter Metaspace GC failed to allocate size "
257 SIZE_FORMAT, _size);
258 }
259 }
260
261 if (_result == NULL && GC_locker::is_active_and_needs_gc()) {
262 set_gc_locked();
263 }
264 }