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rev 2755 : 7099824: G1: we should take the pending list lock before doing the remark pause
Summary: Acquire the pending list lock in the prologue method of G1's
concurrent VM_Operation and release the lock in the epilogue() method.
The locking/unlocking order of the pending list lock and the Heap_lock
should match that in the prologue and epilogue methods of VM_GC_Operation.
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--- old/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp
+++ new/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp
1 1 /*
2 2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
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16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #include "precompiled.hpp"
26 +#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
26 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
27 28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
28 29 #include "gc_implementation/g1/vm_operations_g1.hpp"
29 30 #include "gc_implementation/shared/isGCActiveMark.hpp"
30 31 #include "gc_implementation/g1/vm_operations_g1.hpp"
31 32 #include "runtime/interfaceSupport.hpp"
32 33
33 34 VM_G1CollectForAllocation::VM_G1CollectForAllocation(
34 35 unsigned int gc_count_before,
35 36 size_t word_size)
36 37 : VM_G1OperationWithAllocRequest(gc_count_before, word_size) {
37 38 guarantee(word_size > 0, "an allocation should always be requested");
38 39 }
39 40
40 41 void VM_G1CollectForAllocation::doit() {
41 42 G1CollectedHeap* g1h = G1CollectedHeap::heap();
42 43 _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
43 44 assert(_result == NULL || _pause_succeeded,
44 45 "if we get back a result, the pause should have succeeded");
45 46 }
46 47
47 48 void VM_G1CollectFull::doit() {
48 49 G1CollectedHeap* g1h = G1CollectedHeap::heap();
49 50 GCCauseSetter x(g1h, _gc_cause);
50 51 g1h->do_full_collection(false /* clear_all_soft_refs */);
51 52 }
52 53
53 54 VM_G1IncCollectionPause::VM_G1IncCollectionPause(
54 55 unsigned int gc_count_before,
55 56 size_t word_size,
56 57 bool should_initiate_conc_mark,
57 58 double target_pause_time_ms,
58 59 GCCause::Cause gc_cause)
59 60 : VM_G1OperationWithAllocRequest(gc_count_before, word_size),
60 61 _should_initiate_conc_mark(should_initiate_conc_mark),
61 62 _target_pause_time_ms(target_pause_time_ms),
62 63 _full_collections_completed_before(0) {
63 64 guarantee(target_pause_time_ms > 0.0,
64 65 err_msg("target_pause_time_ms = %1.6lf should be positive",
65 66 target_pause_time_ms));
66 67 guarantee(word_size == 0 || gc_cause == GCCause::_g1_inc_collection_pause,
67 68 "we can only request an allocation if the GC cause is for "
68 69 "an incremental GC pause");
69 70 _gc_cause = gc_cause;
70 71 }
71 72
72 73 void VM_G1IncCollectionPause::doit() {
73 74 G1CollectedHeap* g1h = G1CollectedHeap::heap();
74 75 assert(!_should_initiate_conc_mark ||
75 76 ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
76 77 (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
77 78 "only a GC locker or a System.gc() induced GC should start a cycle");
78 79
79 80 if (_word_size > 0) {
80 81 // An allocation has been requested. So, try to do that first.
81 82 _result = g1h->attempt_allocation_at_safepoint(_word_size,
82 83 false /* expect_null_cur_alloc_region */);
83 84 if (_result != NULL) {
84 85 // If we can successfully allocate before we actually do the
85 86 // pause then we will consider this pause successful.
86 87 _pause_succeeded = true;
87 88 return;
88 89 }
89 90 }
90 91
91 92 GCCauseSetter x(g1h, _gc_cause);
92 93 if (_should_initiate_conc_mark) {
93 94 // It's safer to read full_collections_completed() here, given
94 95 // that noone else will be updating it concurrently. Since we'll
95 96 // only need it if we're initiating a marking cycle, no point in
96 97 // setting it earlier.
97 98 _full_collections_completed_before = g1h->full_collections_completed();
98 99
99 100 // At this point we are supposed to start a concurrent cycle. We
100 101 // will do so if one is not already in progress.
101 102 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
102 103
103 104 // The above routine returns true if we were able to force the
104 105 // next GC pause to be an initial mark; it returns false if a
105 106 // marking cycle is already in progress.
106 107 //
107 108 // If a marking cycle is already in progress just return and skip
108 109 // the pause - the requesting thread should block in doit_epilogue
109 110 // until the marking cycle is complete.
110 111 if (!res) {
111 112 assert(_word_size == 0, "ExplicitGCInvokesConcurrent shouldn't be allocating");
112 113 return;
113 114 }
114 115 }
115 116
116 117 _pause_succeeded =
117 118 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
118 119 if (_pause_succeeded && _word_size > 0) {
119 120 // An allocation had been requested.
120 121 _result = g1h->attempt_allocation_at_safepoint(_word_size,
121 122 true /* expect_null_cur_alloc_region */);
122 123 } else {
123 124 assert(_result == NULL, "invariant");
124 125 }
125 126 }
126 127
127 128 void VM_G1IncCollectionPause::doit_epilogue() {
128 129 VM_GC_Operation::doit_epilogue();
129 130
130 131 // If the pause was initiated by a System.gc() and
131 132 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
132 133 // that just started (or maybe one that was already in progress) to
133 134 // finish.
134 135 if (_gc_cause == GCCause::_java_lang_system_gc &&
135 136 _should_initiate_conc_mark) {
136 137 assert(ExplicitGCInvokesConcurrent,
137 138 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
138 139
139 140 G1CollectedHeap* g1h = G1CollectedHeap::heap();
140 141
141 142 // In the doit() method we saved g1h->full_collections_completed()
142 143 // in the _full_collections_completed_before field. We have to
143 144 // wait until we observe that g1h->full_collections_completed()
144 145 // has increased by at least one. This can happen if a) we started
145 146 // a cycle and it completes, b) a cycle already in progress
146 147 // completes, or c) a Full GC happens.
147 148
148 149 // If the condition has already been reached, there's no point in
149 150 // actually taking the lock and doing the wait.
150 151 if (g1h->full_collections_completed() <=
151 152 _full_collections_completed_before) {
152 153 // The following is largely copied from CMS
153 154
154 155 Thread* thr = Thread::current();
155 156 assert(thr->is_Java_thread(), "invariant");
156 157 JavaThread* jt = (JavaThread*)thr;
157 158 ThreadToNativeFromVM native(jt);
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158 159
159 160 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
160 161 while (g1h->full_collections_completed() <=
161 162 _full_collections_completed_before) {
162 163 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
163 164 }
164 165 }
165 166 }
166 167 }
167 168
169 +void VM_CGC_Operation::acquire_pending_list_lock() {
170 + // The caller may block while communicating
171 + // with the SLT thread in order to acquire/release the PLL.
172 + ConcurrentMarkThread::slt()->
173 + manipulatePLL(SurrogateLockerThread::acquirePLL);
174 +}
175 +
176 +void VM_CGC_Operation::release_and_notify_pending_list_lock() {
177 + // The caller may block while communicating
178 + // with the SLT thread in order to acquire/release the PLL.
179 + ConcurrentMarkThread::slt()->
180 + manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
181 +}
182 +
168 183 void VM_CGC_Operation::doit() {
169 184 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
170 185 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
171 186 TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);
172 187 SharedHeap* sh = SharedHeap::heap();
173 188 // This could go away if CollectedHeap gave access to _gc_is_active...
174 189 if (sh != NULL) {
175 190 IsGCActiveMark x;
176 191 _cl->do_void();
177 192 } else {
178 193 _cl->do_void();
179 194 }
180 195 }
181 196
182 197 bool VM_CGC_Operation::doit_prologue() {
198 + // Note the relative order of the locks must match that in
199 + // VM_GC_Operation::doit_prologue() or deadlocks can occur
200 + acquire_pending_list_lock();
201 +
183 202 Heap_lock->lock();
184 203 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
185 204 return true;
186 205 }
187 206
188 207 void VM_CGC_Operation::doit_epilogue() {
208 + // Note the relative order of the unlocks must match that in
209 + // VM_GC_Operation::doit_epilogue()
189 210 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
190 211 Heap_lock->unlock();
212 + release_and_notify_pending_list_lock();
191 213 }
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