Mon, 26 Jan 2009 12:47:21 -0800
6786503: Overflow list performance can be improved
Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking.
Reviewed-by: jmasa
1 /*
2 * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_permGen.cpp.incl"
28 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) {
29 GCCause::Cause next_cause = GCCause::_permanent_generation_full;
30 GCCause::Cause prev_cause = GCCause::_no_gc;
31 unsigned int gc_count_before, full_gc_count_before;
32 HeapWord* obj;
34 for (;;) {
35 {
36 MutexLocker ml(Heap_lock);
37 if ((obj = gen->allocate(size, false)) != NULL) {
38 return obj;
39 }
40 if (gen->capacity() < _capacity_expansion_limit ||
41 prev_cause != GCCause::_no_gc) {
42 obj = gen->expand_and_allocate(size, false);
43 }
44 if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) {
45 return obj;
46 }
47 if (GC_locker::is_active_and_needs_gc()) {
48 // If this thread is not in a jni critical section, we stall
49 // the requestor until the critical section has cleared and
50 // GC allowed. When the critical section clears, a GC is
51 // initiated by the last thread exiting the critical section; so
52 // we retry the allocation sequence from the beginning of the loop,
53 // rather than causing more, now probably unnecessary, GC attempts.
54 JavaThread* jthr = JavaThread::current();
55 if (!jthr->in_critical()) {
56 MutexUnlocker mul(Heap_lock);
57 // Wait for JNI critical section to be exited
58 GC_locker::stall_until_clear();
59 continue;
60 } else {
61 if (CheckJNICalls) {
62 fatal("Possible deadlock due to allocating while"
63 " in jni critical section");
64 }
65 return NULL;
66 }
67 }
68 // Read the GC count while holding the Heap_lock
69 gc_count_before = SharedHeap::heap()->total_collections();
70 full_gc_count_before = SharedHeap::heap()->total_full_collections();
71 }
73 // Give up heap lock above, VMThread::execute below gets it back
74 VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before,
75 next_cause);
76 VMThread::execute(&op);
77 if (!op.prologue_succeeded() || op.gc_locked()) {
78 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
79 continue; // retry and/or stall as necessary
80 }
81 obj = op.result();
82 assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),
83 "result not in heap");
84 if (obj != NULL) {
85 return obj;
86 }
87 prev_cause = next_cause;
88 next_cause = GCCause::_last_ditch_collection;
89 }
90 }
92 CompactingPermGen::CompactingPermGen(ReservedSpace rs,
93 ReservedSpace shared_rs,
94 size_t initial_byte_size,
95 GenRemSet* remset,
96 PermanentGenerationSpec* perm_spec)
97 {
98 CompactingPermGenGen* g =
99 new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset,
100 NULL, perm_spec);
101 if (g == NULL)
102 vm_exit_during_initialization("Could not allocate a CompactingPermGen");
103 _gen = g;
105 g->initialize_performance_counters();
107 _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion;
108 }
110 HeapWord* CompactingPermGen::mem_allocate(size_t size) {
111 return mem_allocate_in_gen(size, _gen);
112 }
114 void CompactingPermGen::compute_new_size() {
115 size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion);
116 if (desired_capacity < PermSize) {
117 desired_capacity = PermSize;
118 }
119 if (_gen->capacity() > desired_capacity) {
120 _gen->shrink(_gen->capacity() - desired_capacity);
121 }
122 _capacity_expansion_limit = _gen->capacity() + MaxPermHeapExpansion;
123 }