1 #ifdef USE_PRAGMA_IDENT_HDR
2 #pragma ident "@(#)vmGCOperations.cpp 1.21 07/05/29 09:44:12 JVM"
3 #endif
4 /*
5 * Copyright 2005-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27 # include "incls/_precompiled.incl"
28 # include "incls/_vmGCOperations.cpp.incl"
29
30 HS_DTRACE_PROBE_DECL1(hotspot, gc__begin, bool);
31 HS_DTRACE_PROBE_DECL(hotspot, gc__end);
32
33 // The same dtrace probe can't be inserted in two different files, so we
34 // have to call it here, so it's only in one file. Can't create new probes
35 // for the other file anymore. The dtrace probes have to remain stable.
36 void VM_GC_Operation::notify_gc_begin(bool full) {
37 HS_DTRACE_PROBE1(hotspot, gc__begin, full);
38 }
39
40 void VM_GC_Operation::notify_gc_end() {
41 HS_DTRACE_PROBE(hotspot, gc__end);
42 }
43
44 void VM_GC_Operation::acquire_pending_list_lock() {
45 // we may enter this with pending exception set
46 instanceRefKlass::acquire_pending_list_lock(&_pending_list_basic_lock);
47 }
48
49
50 void VM_GC_Operation::release_and_notify_pending_list_lock() {
51
52 instanceRefKlass::release_and_notify_pending_list_lock(&_pending_list_basic_lock);
53 }
54
55 // Allocations may fail in several threads at about the same time,
56 // resulting in multiple gc requests. We only want to do one of them.
57 // In case a GC locker is active and the need for a GC is already signalled,
58 // we want to skip this GC attempt altogether, without doing a futile
59 // safepoint operation.
60 bool VM_GC_Operation::skip_operation() const {
61 bool skip = (_gc_count_before != Universe::heap()->total_collections());
62 if (_full && skip) {
63 skip = (_full_gc_count_before != Universe::heap()->total_full_collections());
64 }
65 if (!skip && GC_locker::is_active_and_needs_gc()) {
66 skip = Universe::heap()->is_maximal_no_gc();
67 assert(!(skip && (_gc_cause == GCCause::_gc_locker)),
68 "GC_locker cannot be active when initiating GC");
69 }
70 return skip;
71 }
72
73 bool VM_GC_Operation::doit_prologue() {
74 assert(Thread::current()->is_Java_thread(), "just checking");
75
76 acquire_pending_list_lock();
77 // If the GC count has changed someone beat us to the collection
78 // Get the Heap_lock after the pending_list_lock.
79 Heap_lock->lock();
80
81 // Check invocations
82 if (skip_operation()) {
83 // skip collection
84 Heap_lock->unlock();
85 release_and_notify_pending_list_lock();
86 _prologue_succeeded = false;
87 } else {
88 _prologue_succeeded = true;
89 SharedHeap* sh = SharedHeap::heap();
90 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = true;
91 }
92 return _prologue_succeeded;
93 }
94
95
96 void VM_GC_Operation::doit_epilogue() {
97 assert(Thread::current()->is_Java_thread(), "just checking");
98 // Release the Heap_lock first.
99 SharedHeap* sh = SharedHeap::heap();
100 if (sh != NULL) sh->_thread_holds_heap_lock_for_gc = false;
101 Heap_lock->unlock();
102 release_and_notify_pending_list_lock();
103 }
104
105 bool VM_GC_HeapInspection::doit_prologue() {
106 if (Universe::heap()->supports_heap_inspection()) {
107 return VM_GC_Operation::doit_prologue();
108 } else {
109 return false;
110 }
111 }
112
113 bool VM_GC_HeapInspection::skip_operation() const {
114 assert(Universe::heap()->supports_heap_inspection(), "huh?");
115 return false;
116 }
117
118 void VM_GC_HeapInspection::doit() {
119 HandleMark hm;
120 CollectedHeap* ch = Universe::heap();
121 if (_full_gc) {
122 ch->collect_as_vm_thread(GCCause::_heap_inspection);
123 } else {
124 // make the heap parsable (no need to retire TLABs)
125 ch->ensure_parsability(false);
126 }
127 HeapInspection::heap_inspection(_out);
128 }
129
130
131 void VM_GenCollectForAllocation::doit() {
132 JvmtiGCForAllocationMarker jgcm;
133 notify_gc_begin(false);
134
135 GenCollectedHeap* gch = GenCollectedHeap::heap();
136 GCCauseSetter gccs(gch, _gc_cause);
137 _res = gch->satisfy_failed_allocation(_size, _tlab);
138 assert(gch->is_in_reserved_or_null(_res), "result not in heap");
139
140 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
141 set_gc_locked();
142 }
143 notify_gc_end();
144 }
145
146 void VM_GenCollectFull::doit() {
147 JvmtiGCFullMarker jgcm;
148 notify_gc_begin(true);
149
150 GenCollectedHeap* gch = GenCollectedHeap::heap();
151 GCCauseSetter gccs(gch, _gc_cause);
152 gch->do_full_collection(gch->must_clear_all_soft_refs(), _max_level);
153 notify_gc_end();
154 }
155
156 void VM_GenCollectForPermanentAllocation::doit() {
157 JvmtiGCForAllocationMarker jgcm;
158 notify_gc_begin(true);
159 SharedHeap* heap = (SharedHeap*)Universe::heap();
160 GCCauseSetter gccs(heap, _gc_cause);
161 switch (heap->kind()) {
162 case (CollectedHeap::GenCollectedHeap): {
163 GenCollectedHeap* gch = (GenCollectedHeap*)heap;
164 gch->do_full_collection(gch->must_clear_all_soft_refs(),
165 gch->n_gens() - 1);
166 break;
167 }
168 #ifndef SERIALGC
169 case (CollectedHeap::G1CollectedHeap): {
170 G1CollectedHeap* g1h = (G1CollectedHeap*)heap;
171 g1h->do_full_collection(_gc_cause == GCCause::_last_ditch_collection);
172 break;
173 }
174 #endif // SERIALGC
175 default:
176 ShouldNotReachHere();
177 }
178 _res = heap->perm_gen()->allocate(_size, false);
179 assert(heap->is_in_reserved_or_null(_res), "result not in heap");
180 if (_res == NULL && GC_locker::is_active_and_needs_gc()) {
181 set_gc_locked();
182 }
183 notify_gc_end();
184 }