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comparison src/share/vm/memory/permGen.cpp @ 480:d249b360e026

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6782457: CMS: Livelock in CompactibleFreeListSpace::block_size() 6736295: SIGSEGV in product jvm, assertion "these are the only valid states during a mark sweep" in fastdebug Summary: Restructured the code in the perm gen allocation retry loop so as to avoid "safepoint-blocking" on locks, in this case the Heap_lock, while holding uninitialized allocated heap storage. Reviewed-by: apetrusenko, iveresov, jcoomes, jmasa, poonam
author ysr
date Wed, 10 Dec 2008 23:46:10 -0800
parents d1605aabd0a1
children 0fbdb4381b99
comparison
equal deleted inserted replaced
464:8a0c882e46d6 480:d249b360e026
24 24
25 #include "incls/_precompiled.incl" 25 #include "incls/_precompiled.incl"
26 #include "incls/_permGen.cpp.incl" 26 #include "incls/_permGen.cpp.incl"
27 27
28 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) { 28 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) {
29 MutexLocker ml(Heap_lock);
30 GCCause::Cause next_cause = GCCause::_permanent_generation_full; 29 GCCause::Cause next_cause = GCCause::_permanent_generation_full;
31 GCCause::Cause prev_cause = GCCause::_no_gc; 30 GCCause::Cause prev_cause = GCCause::_no_gc;
31 unsigned int gc_count_before, full_gc_count_before;
32 HeapWord* obj;
32 33
33 for (;;) { 34 for (;;) {
34 HeapWord* obj = gen->allocate(size, false); 35 {
35 if (obj != NULL) { 36 MutexLocker ml(Heap_lock);
36 return obj; 37 if ((obj = gen->allocate(size, false)) != NULL) {
37 } 38 return obj;
38 if (gen->capacity() < _capacity_expansion_limit || 39 }
39 prev_cause != GCCause::_no_gc) { 40 if (gen->capacity() < _capacity_expansion_limit ||
40 obj = gen->expand_and_allocate(size, false); 41 prev_cause != GCCause::_no_gc) {
41 } 42 obj = gen->expand_and_allocate(size, false);
42 if (obj == NULL && prev_cause != GCCause::_last_ditch_collection) { 43 }
44 if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) {
45 return obj;
46 }
43 if (GC_locker::is_active_and_needs_gc()) { 47 if (GC_locker::is_active_and_needs_gc()) {
44 // If this thread is not in a jni critical section, we stall 48 // If this thread is not in a jni critical section, we stall
45 // the requestor until the critical section has cleared and 49 // the requestor until the critical section has cleared and
46 // GC allowed. When the critical section clears, a GC is 50 // GC allowed. When the critical section clears, a GC is
47 // initiated by the last thread exiting the critical section; so 51 // initiated by the last thread exiting the critical section; so
59 " in jni critical section"); 63 " in jni critical section");
60 } 64 }
61 return NULL; 65 return NULL;
62 } 66 }
63 } 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 }
64 72
65 // Read the GC count while holding the Heap_lock 73 // Give up heap lock above, VMThread::execute below gets it back
66 unsigned int gc_count_before = SharedHeap::heap()->total_collections(); 74 VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before,
67 unsigned int full_gc_count_before = SharedHeap::heap()->total_full_collections(); 75 next_cause);
68 { 76 VMThread::execute(&op);
69 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 77 if (!op.prologue_succeeded() || op.gc_locked()) {
70 VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before, 78 assert(op.result() == NULL, "must be NULL if gc_locked() is true");
71 next_cause); 79 continue; // retry and/or stall as necessary
72 VMThread::execute(&op); 80 }
73 if (!op.prologue_succeeded() || op.gc_locked()) { 81 obj = op.result();
74 assert(op.result() == NULL, "must be NULL if gc_locked() is true"); 82 assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),
75 continue; // retry and/or stall as necessary 83 "result not in heap");
76 } 84 if (obj != NULL) {
77 obj = op.result();
78 assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),
79 "result not in heap");
80 if (obj != NULL) {
81 return obj;
82 }
83 }
84 prev_cause = next_cause;
85 next_cause = GCCause::_last_ditch_collection;
86 } else {
87 return obj; 85 return obj;
88 } 86 }
87 prev_cause = next_cause;
88 next_cause = GCCause::_last_ditch_collection;
89 } 89 }
90 } 90 }
91 91
92 CompactingPermGen::CompactingPermGen(ReservedSpace rs, 92 CompactingPermGen::CompactingPermGen(ReservedSpace rs,
93 ReservedSpace shared_rs, 93 ReservedSpace shared_rs,