1 /*
2 * Copyright (c) 2005, 2008, 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 # include "incls/_precompiled.incl"
25 # include "incls/_vmGCOperations.cpp.incl"
26
27 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
28 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
29
30 // The same dtrace probe can't be inserted in two different files, so we
31 // have to call it here, so it's only in one file. Can't create new probes
32 // for the other file anymore. The dtrace probes have to remain stable.
33 void VM_GC_Operation::notify_gc_begin(bool full) {
34 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
35 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
36 }
37
38 void VM_GC_Operation::notify_gc_end() {
39 HS_DTRACE_PROBE(hotspot, gc__end);
40 HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
41 }
42
43 void VM_GC_Operation::acquire_pending_list_lock() {
44 // we may enter this with pending exception set
45 instanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
46 }
47
48
49 void VM_GC_Operation::release_and_notify_pending_list_lock() {
50
51 instanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
52 }
53
54 // Allocations may fail in several threads at about the same time,
55 // resulting in multiple gc requests. We only want to do one of them.
56 // In case a GC locker is active and the need for a GC is already signalled,
57 // we want to skip this GC attempt altogether, without doing a futile
58 // safepoint operation.
59 bool VM_GC_Operation::skip_operation() const {
60 bool skip = (_gc_count_before != Universe::heap()->total_collections());
61 if (_full && skip) {
62 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
63 }
64 if (!skip && GC_locker::is_active_and_needs_gc()) {
65 skip = Universe::heap()->is_maximal_no_gc();
66 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
67 "GC_locker cannot be active when initiating GC");
68 }
69 return skip;
70 }
71
72 bool VM_GC_Operation::doit_prologue() {
73 assert(Thread::current()->is_Java_thread(), "just checking");
74
75 acquire_pending_list_lock();
76 // If the GC count has changed someone beat us to the collection
77 // Get the Heap_lock after the pending_list_lock.
78 Heap_lock->lock();
79
80 // Check invocations
81 if (skip_operation()) {
82 // skip collection
83 Heap_lock->unlock();
84 release_and_notify_pending_list_lock();
85 _prologue_succeeded = false;
86 } else {
87 _prologue_succeeded = true;
88 SharedHeap* sh = SharedHeap::heap();
89 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
90 }
91 return _prologue_succeeded;
92 }
93
94
95 void VM_GC_Operation::doit_epilogue() {
96 assert(Thread::current()->is_Java_thread(), "just checking");
97 // Release the Heap_lock first.
98 SharedHeap* sh = SharedHeap::heap();
99 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
100 Heap_lock->unlock();
101 release_and_notify_pending_list_lock();
102 }
103
104 bool VM_GC_HeapInspection::doit_prologue() {
105 if (Universe::heap()->supports_heap_inspection()) {
106 return VM_GC_Operation::doit_prologue();
107 } else {
108 return false;
109 }
110 }
111
112 bool VM_GC_HeapInspection::skip_operation() const {
113 assert(Universe::heap()->supports_heap_inspection(), "huh?");
114 return false;
115 }
116
117 void VM_GC_HeapInspection::doit() {
118 HandleMark hm;
119 CollectedHeap* ch = Universe::heap();
120 ch->ensure_parsability(false); // must happen, even if collection does
121 // not happen (e.g. due to GC_locker)
122 if (_full_gc) {
123 // The collection attempt below would be skipped anyway if
124 // the gc locker is held. The following dump may then be a tad
125 // misleading to someone expecting only live objects to show
126 // up in the dump (see CR 6944195). Just issue a suitable warning
127 // in that case and do not attempt to do a collection.
128 // The latter is a subtle point, because even a failed attempt
129 // to GC will, in fact, induce one in the future, which we
130 // probably want to avoid in this case because the GC that we may
131 // be about to attempt holds value for us only
132 // if it happens now and not if it happens in the eventual
133 // future.
134 if (GC_locker::is_active()) {
135 warning("GC locker is held; pre-dump GC was skipped");
136 } else {
137 ch->collect_as_vm_thread(GCCause::_heap_inspection);
138 }
139 }
140 HeapInspection::heap_inspection(_out, _need_prologue /* need_prologue */);
141 }
142
143
144 void VM_GenCollectForAllocation::doit() {
145 JvmtiGCForAllocationMarker jgcm;
146 notify_gc_begin(false);
147
148 GenCollectedHeap* gch = GenCollectedHeap::heap();
149 GCCauseSetter gccs(gch, _gc_cause);
150 _res = gch->satisfy_failed_allocation(_size, _tlab);
151 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
152
153 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
154 set_gc_locked();
155 }
156 notify_gc_end();
157 }
158
159 void VM_GenCollectFull::doit() {
160 JvmtiGCFullMarker jgcm;
161 notify_gc_begin(true);
162
163 GenCollectedHeap* gch = GenCollectedHeap::heap();
164 GCCauseSetter gccs(gch, _gc_cause);
165 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
166 notify_gc_end();
167 }
168
169 void VM_GenCollectForPermanentAllocation::doit() {
170 JvmtiGCForAllocationMarker jgcm;
171 notify_gc_begin(true);
172 SharedHeap* heap = (SharedHeap*)Universe::heap();
173 GCCauseSetter gccs(heap, _gc_cause);
174 switch (heap->kind()) {
175 case (CollectedHeap::GenCollectedHeap): {
176 GenCollectedHeap* gch = (GenCollectedHeap*)heap;
177 gch->do_full_collection(gch->must_clear_all_soft_refs(),
178 gch->n_gens() - 1);
179 break;
180 }
181 #ifndef SERIALGC
182 case (CollectedHeap::G1CollectedHeap): {
183 G1CollectedHeap* g1h = (G1CollectedHeap*)heap;
184 g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);
185 break;
186 }
187 #endif // SERIALGC
188 default:
189 ShouldNotReachHere();
190 }
191 _res = heap->perm_gen()->allocate(_size, false);
192 assert(heap->is_in_reserved_or_null(_res), "result not in heap");
193 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
194 set_gc_locked();
195 }
196 notify_gc_end();
197 }