1 /*
2 * Copyright (c) 2005, 2011, 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 bool VM_GC_HeapInspection::collect() {
148 CollectedHeap* ch = Universe::heap();
149 ch->ensure_parsability(false); // must happen, even if collection does
150 // not happen (e.g. due to GC_locker)
151
152 if (GC_locker::is_active()) {
153 return false;
154 }
155 ch->collect_as_vm_thread(GCCause::_heap_inspection);
156 return true;
157 }
158
159 void VM_GC_HeapInspection::doit() {
160 HandleMark hm;
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::heap_inspection(_out, _need_prologue /* need_prologue */);
177 }
178
179
180 void VM_GenCollectForAllocation::doit() {
181 SvcGCMarker sgcm(SvcGCMarker::MINOR);
182
183 GenCollectedHeap* gch = GenCollectedHeap::heap();
184 GCCauseSetter gccs(gch, _gc_cause);
185 _res = gch->satisfy_failed_allocation(_size, _tlab);
186 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
187
188 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
189 set_gc_locked();
190 }
191 }
192
193 void VM_GenCollectFull::doit() {
194 SvcGCMarker sgcm(SvcGCMarker::FULL);
195
196 GenCollectedHeap* gch = GenCollectedHeap::heap();
197 GCCauseSetter gccs(gch, _gc_cause);
198 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
199 }
200
201 void VM_GenCollectForPermanentAllocation::doit() {
202 SvcGCMarker sgcm(SvcGCMarker::FULL);
203
204 SharedHeap* heap = (SharedHeap*)Universe::heap();
205 GCCauseSetter gccs(heap, _gc_cause);
206 switch (heap->kind()) {
207 case (CollectedHeap::GenCollectedHeap): {
208 GenCollectedHeap* gch = (GenCollectedHeap*)heap;
209 gch->do_full_collection(gch->must_clear_all_soft_refs(),
210 gch->n_gens() - 1);
211 break;
212 }
213 #ifndef SERIALGC
214 case (CollectedHeap::G1CollectedHeap): {
215 G1CollectedHeap* g1h = (G1CollectedHeap*)heap;
216 g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);
217 break;
218 }
219 #endif // SERIALGC
220 default:
221 ShouldNotReachHere();
222 }
223 _res = heap->perm_gen()->allocate(_size, false);
224 assert(heap->is_in_reserved_or_null(_res), "result not in heap");
225 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
226 set_gc_locked();
227 }
228 }