Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/g1/concurrentZFThread.cpp @ 1995:8df09fb45352
7005259: CMS: BubbleUpRef asserts referent(obj)->is_oop() failed: Enqueued a bad referent
Summary: Relaxed the assert by allowing NULL referents when discovery may be concurrent.
Reviewed-by: johnc, jcoomes
author | ysr |
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date | Thu, 09 Dec 2010 09:22:57 -0800 |
parents | f95d63e2154a |
children |
rev | line source |
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342 | 1 /* |
1972 | 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
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4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
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7 * published by the Free Software Foundation. | |
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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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/g1/concurrentZFThread.hpp" | |
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" | |
28 #include "gc_implementation/g1/heapRegion.hpp" | |
29 #include "memory/space.inline.hpp" | |
30 #include "runtime/mutexLocker.hpp" | |
31 #include "utilities/copy.hpp" | |
342 | 32 |
33 // ======= Concurrent Zero-Fill Thread ======== | |
34 | |
35 // The CM thread is created when the G1 garbage collector is used | |
36 | |
37 int ConcurrentZFThread::_region_allocs = 0; | |
38 int ConcurrentZFThread::_sync_zfs = 0; | |
39 int ConcurrentZFThread::_zf_waits = 0; | |
40 int ConcurrentZFThread::_regions_filled = 0; | |
41 | |
42 ConcurrentZFThread::ConcurrentZFThread() : | |
936 | 43 ConcurrentGCThread() |
342 | 44 { |
45 create_and_start(); | |
46 } | |
47 | |
48 void ConcurrentZFThread::wait_for_ZF_completed(HeapRegion* hr) { | |
49 assert(ZF_mon->owned_by_self(), "Precondition."); | |
50 note_zf_wait(); | |
51 while (hr->zero_fill_state() == HeapRegion::ZeroFilling) { | |
52 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
53 } | |
54 } | |
55 | |
56 void ConcurrentZFThread::processHeapRegion(HeapRegion* hr) { | |
57 assert(!Universe::heap()->is_gc_active(), | |
58 "This should not happen during GC."); | |
59 assert(hr != NULL, "Precondition"); | |
60 // These are unlocked reads, but if this test is successful, then no | |
61 // other thread will attempt this zero filling. Only a GC thread can | |
62 // modify the ZF state of a region whose state is zero-filling, and this | |
63 // should only happen while the ZF thread is locking out GC. | |
64 if (hr->zero_fill_state() == HeapRegion::ZeroFilling | |
65 && hr->zero_filler() == Thread::current()) { | |
66 assert(hr->top() == hr->bottom(), "better be empty!"); | |
67 assert(!hr->isHumongous(), "Only free regions on unclean list."); | |
68 Copy::fill_to_words(hr->bottom(), hr->capacity()/HeapWordSize); | |
69 note_region_filled(); | |
70 } | |
71 } | |
72 | |
73 void ConcurrentZFThread::run() { | |
74 initialize_in_thread(); | |
75 Thread* thr_self = Thread::current(); | |
76 _vtime_start = os::elapsedVTime(); | |
77 wait_for_universe_init(); | |
78 | |
79 G1CollectedHeap* g1 = G1CollectedHeap::heap(); | |
80 _sts.join(); | |
81 while (!_should_terminate) { | |
82 _sts.leave(); | |
83 | |
84 { | |
85 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); | |
86 | |
87 // This local variable will hold a region being zero-filled. This | |
88 // region will neither be on the unclean or zero-filled lists, and | |
89 // will not be available for allocation; thus, we might have an | |
90 // allocation fail, causing a full GC, because of this, but this is a | |
91 // price we will pay. (In future, we might want to make the fact | |
92 // that there's a region being zero-filled apparent to the G1 heap, | |
93 // which could then wait for it in this extreme case...) | |
94 HeapRegion* to_fill; | |
95 | |
96 while (!g1->should_zf() | |
97 || (to_fill = g1->pop_unclean_region_list_locked()) == NULL) | |
98 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
99 while (to_fill->zero_fill_state() == HeapRegion::ZeroFilling) | |
100 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
101 | |
102 // So now to_fill is non-NULL and is not ZeroFilling. It might be | |
103 // Allocated or ZeroFilled. (The latter could happen if this thread | |
104 // starts the zero-filling of a region, but a GC intervenes and | |
105 // pushes new regions needing on the front of the filling on the | |
106 // front of the list.) | |
107 | |
108 switch (to_fill->zero_fill_state()) { | |
109 case HeapRegion::Allocated: | |
110 to_fill = NULL; | |
111 break; | |
112 | |
113 case HeapRegion::NotZeroFilled: | |
114 to_fill->set_zero_fill_in_progress(thr_self); | |
115 | |
116 ZF_mon->unlock(); | |
117 _sts.join(); | |
118 processHeapRegion(to_fill); | |
119 _sts.leave(); | |
120 ZF_mon->lock_without_safepoint_check(); | |
121 | |
122 if (to_fill->zero_fill_state() == HeapRegion::ZeroFilling | |
123 && to_fill->zero_filler() == thr_self) { | |
124 to_fill->set_zero_fill_complete(); | |
125 (void)g1->put_free_region_on_list_locked(to_fill); | |
126 } | |
127 break; | |
128 | |
129 case HeapRegion::ZeroFilled: | |
130 (void)g1->put_free_region_on_list_locked(to_fill); | |
131 break; | |
132 | |
133 case HeapRegion::ZeroFilling: | |
134 ShouldNotReachHere(); | |
135 break; | |
136 } | |
137 } | |
138 _vtime_accum = (os::elapsedVTime() - _vtime_start); | |
139 _sts.join(); | |
140 } | |
141 _sts.leave(); | |
142 | |
143 assert(_should_terminate, "just checking"); | |
144 terminate(); | |
145 } | |
146 | |
147 bool ConcurrentZFThread::offer_yield() { | |
148 if (_sts.should_yield()) { | |
149 _sts.yield("Concurrent ZF"); | |
150 return true; | |
151 } else { | |
152 return false; | |
153 } | |
154 } | |
155 | |
156 void ConcurrentZFThread::stop() { | |
157 // it is ok to take late safepoints here, if needed | |
158 MutexLockerEx mu(Terminator_lock); | |
159 _should_terminate = true; | |
160 while (!_has_terminated) { | |
161 Terminator_lock->wait(); | |
162 } | |
163 } | |
164 | |
1019 | 165 void ConcurrentZFThread::print() const { |
166 print_on(tty); | |
167 } | |
168 | |
169 void ConcurrentZFThread::print_on(outputStream* st) const { | |
170 st->print("\"G1 Concurrent Zero-Fill Thread\" "); | |
171 Thread::print_on(st); | |
172 st->cr(); | |
342 | 173 } |
174 | |
175 | |
176 double ConcurrentZFThread::_vtime_accum; | |
177 | |
178 void ConcurrentZFThread::print_summary_info() { | |
179 gclog_or_tty->print("\nConcurrent Zero-Filling:\n"); | |
180 gclog_or_tty->print(" Filled %d regions, used %5.2fs.\n", | |
181 _regions_filled, | |
182 vtime_accum()); | |
183 gclog_or_tty->print(" Of %d region allocs, %d (%5.2f%%) required sync ZF,\n", | |
184 _region_allocs, _sync_zfs, | |
185 (_region_allocs > 0 ? | |
186 (float)_sync_zfs/(float)_region_allocs*100.0 : | |
187 0.0)); | |
188 gclog_or_tty->print(" and %d (%5.2f%%) required a ZF wait.\n", | |
189 _zf_waits, | |
190 (_region_allocs > 0 ? | |
191 (float)_zf_waits/(float)_region_allocs*100.0 : | |
192 0.0)); | |
193 | |
194 } |