1 /*
2 * Copyright (c) 2005, 2010, 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 "prims/jvmtiExport.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/init.hpp"
37 #include "runtime/interfaceSupport.hpp"
38 #include "utilities/dtrace.hpp"
39 #include "utilities/preserveException.hpp"
40 #ifndef SERIALGC
41 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
42 #endif
43 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
44 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
45
46 // The same dtrace probe can't be inserted in two different files, so we
47 // have to call it here, so it's only in one file. Can't create new probes
48 // for the other file anymore. The dtrace probes have to remain stable.
49 void VM_GC_Operation::notify_gc_begin(bool full) {
50 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
51 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
52 }
53
54 void VM_GC_Operation::notify_gc_end() {
55 HS_DTRACE_PROBE(hotspot, gc__end);
56 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
57 }
58
59 void VM_GC_Operation::acquire_pending_list_lock() {
60 // we may enter this with pending exception set
61 instanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
62 }
63
64
65 void VM_GC_Operation::release_and_notify_pending_list_lock() {
66
67 instanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
68 }
69
70 // Allocations may fail in several threads at about the same time,
71 // resulting in multiple gc requests. We only want to do one of them.
72 // In case a GC locker is active and the need for a GC is already signalled,
73 // we want to skip this GC attempt altogether, without doing a futile
74 // safepoint operation.
75 bool VM_GC_Operation::skip_operation() const {
76 bool skip = (_gc_count_before != Universe::heap()->total_collections());
77 if (_full && skip) {
78 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
79 }
80 if (!skip && GC_locker::is_active_and_needs_gc()) {
81 skip = Universe::heap()->is_maximal_no_gc();
82 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
83 "GC_locker cannot be active when initiating GC");
84 }
85 return skip;
86 }
87
88 bool VM_GC_Operation::doit_prologue() {
89 assert(Thread::current()->is_Java_thread(), "just checking");
90
91 acquire_pending_list_lock();
92 // If the GC count has changed someone beat us to the collection
93 // Get the Heap_lock after the pending_list_lock.
94 Heap_lock->lock();
95
96 // Check invocations
97 if (skip_operation()) {
98 // skip collection
99 Heap_lock->unlock();
100 release_and_notify_pending_list_lock();
101 _prologue_succeeded = false;
102 } else {
103 _prologue_succeeded = true;
104 SharedHeap* sh = SharedHeap::heap();
105 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
106 }
107 return _prologue_succeeded;
108 }
109
110
111 void VM_GC_Operation::doit_epilogue() {
112 assert(Thread::current()->is_Java_thread(), "just checking");
113 // Release the Heap_lock first.
114 SharedHeap* sh = SharedHeap::heap();
115 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
116 Heap_lock->unlock();
117 release_and_notify_pending_list_lock();
118 }
119
120 bool VM_GC_HeapInspection::doit_prologue() {
121 if (Universe::heap()->supports_heap_inspection()) {
122 return VM_GC_Operation::doit_prologue();
123 } else {
124 return false;
125 }
126 }
127
128 bool VM_GC_HeapInspection::skip_operation() const {
129 assert(Universe::heap()->supports_heap_inspection(), "huh?");
130 return false;
131 }
132
133 void VM_GC_HeapInspection::doit() {
134 HandleMark hm;
135 CollectedHeap* ch = Universe::heap();
136 ch->ensure_parsability(false); // must happen, even if collection does
137 // not happen (e.g. due to GC_locker)
138 if (_full_gc) {
139 // The collection attempt below would be skipped anyway if
140 // the gc locker is held. The following dump may then be a tad
141 // misleading to someone expecting only live objects to show
142 // up in the dump (see CR 6944195). Just issue a suitable warning
143 // in that case and do not attempt to do a collection.
144 // The latter is a subtle point, because even a failed attempt
145 // to GC will, in fact, induce one in the future, which we
146 // probably want to avoid in this case because the GC that we may
147 // be about to attempt holds value for us only
148 // if it happens now and not if it happens in the eventual
149 // future.
150 if (GC_locker::is_active()) {
151 warning("GC locker is held; pre-dump GC was skipped");
152 } else {
153 ch->collect_as_vm_thread(GCCause::_heap_inspection);
154 }
155 }
156 HeapInspection::heap_inspection(_out, _need_prologue /* need_prologue */);
157 }
158
159
160 void VM_GenCollectForAllocation::doit() {
161 JvmtiGCForAllocationMarker jgcm;
162 notify_gc_begin(false);
163
164 GenCollectedHeap* gch = GenCollectedHeap::heap();
165 GCCauseSetter gccs(gch, _gc_cause);
166 _res = gch->satisfy_failed_allocation(_size, _tlab);
167 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
168
169 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
170 set_gc_locked();
171 }
172 notify_gc_end();
173 }
174
175 void VM_GenCollectFull::doit() {
176 JvmtiGCFullMarker jgcm;
177 notify_gc_begin(true);
178
179 GenCollectedHeap* gch = GenCollectedHeap::heap();
180 GCCauseSetter gccs(gch, _gc_cause);
181 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
182 notify_gc_end();
183 }
184
185 void VM_GenCollectForPermanentAllocation::doit() {
186 JvmtiGCForAllocationMarker jgcm;
187 notify_gc_begin(true);
188 SharedHeap* heap = (SharedHeap*)Universe::heap();
189 GCCauseSetter gccs(heap, _gc_cause);
190 switch (heap->kind()) {
191 case (CollectedHeap::GenCollectedHeap): {
192 GenCollectedHeap* gch = (GenCollectedHeap*)heap;
193 gch->do_full_collection(gch->must_clear_all_soft_refs(),
194 gch->n_gens() - 1);
195 break;
196 }
197 #ifndef SERIALGC
198 case (CollectedHeap::G1CollectedHeap): {
199 G1CollectedHeap* g1h = (G1CollectedHeap*)heap;
200 g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);
201 break;
202 }
203 #endif // SERIALGC
204 default:
205 ShouldNotReachHere();
206 }
207 _res = heap->perm_gen()->allocate(_size, false);
208 assert(heap->is_in_reserved_or_null(_res), "result not in heap");
209 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
210 set_gc_locked();
211 }
212 notify_gc_end();
213 }