Wed, 18 Jan 2012 09:50:16 -0800
7129514: time warp warnings after 7117303
Summary: Replace calls to os::javaTimeMillis() that are used to update the milliseconds since the last GC to an equivalent that uses a monotonically non-decreasing time source.
Reviewed-by: ysr, jmasa
1 /*
2 * Copyright (c) 2000, 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.
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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.
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/shared/cSpaceCounters.hpp"
27 #include "gc_implementation/shared/vmGCOperations.hpp"
28 #include "gc_interface/collectedHeap.inline.hpp"
29 #include "memory/blockOffsetTable.inline.hpp"
30 #include "memory/compactPermGen.hpp"
31 #include "memory/gcLocker.hpp"
32 #include "memory/gcLocker.inline.hpp"
33 #include "memory/genCollectedHeap.hpp"
34 #include "memory/generation.inline.hpp"
35 #include "memory/permGen.hpp"
36 #include "memory/universe.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/java.hpp"
39 #include "runtime/vmThread.hpp"
41 HeapWord* PermGen::request_expand_and_allocate(Generation* gen, size_t size,
42 GCCause::Cause prev_cause) {
43 if (gen->capacity() < _capacity_expansion_limit ||
44 prev_cause != GCCause::_no_gc || UseG1GC) { // last disjunct is a temporary hack for G1
45 return gen->expand_and_allocate(size, false);
46 }
47 // We have reached the limit of capacity expansion where
48 // we will not expand further until a GC is done; request denied.
49 return NULL;
50 }
52 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) {
53 GCCause::Cause next_cause = GCCause::_permanent_generation_full;
54 GCCause::Cause prev_cause = GCCause::_no_gc;
55 unsigned int gc_count_before, full_gc_count_before;
56 HeapWord* obj;
58 for (;;) {
59 {
60 MutexLocker ml(Heap_lock);
61 if ((obj = gen->allocate(size, false)) != NULL) {
62 return obj;
63 }
64 // Attempt to expand and allocate the requested space:
65 // specific subtypes may use specific policy to either expand
66 // or not. The default policy (see above) is to expand until
67 // _capacity_expansion_limit, and no further unless a GC is done.
68 // Concurrent collectors may decide to kick off a concurrent
69 // collection under appropriate conditions.
70 obj = request_expand_and_allocate(gen, size, prev_cause);
72 if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) {
73 return obj;
74 }
75 if (GC_locker::is_active_and_needs_gc()) {
76 // If this thread is not in a jni critical section, we stall
77 // the requestor until the critical section has cleared and
78 // GC allowed. When the critical section clears, a GC is
79 // initiated by the last thread exiting the critical section; so
80 // we retry the allocation sequence from the beginning of the loop,
81 // rather than causing more, now probably unnecessary, GC attempts.
82 JavaThread* jthr = JavaThread::current();
83 if (!jthr->in_critical()) {
84 MutexUnlocker mul(Heap_lock);
85 // Wait for JNI critical section to be exited
86 GC_locker::stall_until_clear();
87 continue;
88 } else {
89 if (CheckJNICalls) {
90 fatal("Possible deadlock due to allocating while"
91 " in jni critical section");
92 }
93 return NULL;
94 }
95 }
96 // Read the GC count while holding the Heap_lock
97 gc_count_before = SharedHeap::heap()->total_collections();
98 full_gc_count_before = SharedHeap::heap()->total_full_collections();
99 }
101 // Give up heap lock above, VMThread::execute below gets it back
102 VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before,
103 next_cause);
104 VMThread::execute(&op);
105 if (!op.prologue_succeeded() || op.gc_locked()) {
106 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
107 continue; // retry and/or stall as necessary
108 }
109 obj = op.result();
110 assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),
111 "result not in heap");
112 if (obj != NULL) {
113 return obj;
114 }
115 prev_cause = next_cause;
116 next_cause = GCCause::_last_ditch_collection;
117 }
118 }
120 CompactingPermGen::CompactingPermGen(ReservedSpace rs,
121 ReservedSpace shared_rs,
122 size_t initial_byte_size,
123 GenRemSet* remset,
124 PermanentGenerationSpec* perm_spec)
125 {
126 CompactingPermGenGen* g =
127 new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset,
128 NULL, perm_spec);
129 if (g == NULL)
130 vm_exit_during_initialization("Could not allocate a CompactingPermGen");
131 _gen = g;
133 g->initialize_performance_counters();
135 _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion;
136 }
138 HeapWord* CompactingPermGen::mem_allocate(size_t size) {
139 return mem_allocate_in_gen(size, _gen);
140 }
142 void CompactingPermGen::compute_new_size() {
143 size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion);
144 if (desired_capacity < PermSize) {
145 desired_capacity = PermSize;
146 }
147 if (_gen->capacity() > desired_capacity) {
148 _gen->shrink(_gen->capacity() - desired_capacity);
149 }
150 set_capacity_expansion_limit(_gen->capacity() + MaxPermHeapExpansion);
151 }