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7143858: G1: Back to back young GCs with the second GC having a minimally sized eden

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Before the last thread to leave a JNI critical region was able to schedule a GCLocker Initiated GC, another thread was attempting an allocation and saw that the GCLocker region was no longer active and successfully scheduled a GC. Stall allocating threads until the GCLocker Initiated GC is performed and then retry the allocation.

Reviewed-by: brutisso, huntch
This commit is contained in:
John Cuthbertson 2012-05-29 10:18:02 -07:00
parent 818597ae4f
commit 3f38785a0a
1 changed files with 30 additions and 6 deletions
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36
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
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@ -952,9 +952,18 @@ HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
}
should_try_gc = false;
} else {
// Read the GC count while still holding the Heap_lock.
gc_count_before = total_collections();
should_try_gc = true;
// The GCLocker may not be active but the GCLocker initiated
// GC may not yet have been performed (GCLocker::needs_gc()
// returns true). In this case we do not try this GC and
// wait until the GCLocker initiated GC is performed, and
// then retry the allocation.
if (GC_locker::needs_gc()) {
should_try_gc = false;
} else {
// Read the GC count while still holding the Heap_lock.
gc_count_before = total_collections();
should_try_gc = true;
}
}
}
@ -975,6 +984,9 @@ HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
return NULL;
}
} else {
// The GCLocker is either active or the GCLocker initiated
// GC has not yet been performed. Stall until it is and
// then retry the allocation.
GC_locker::stall_until_clear();
}
@ -1054,9 +1066,18 @@ HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
if (GC_locker::is_active_and_needs_gc()) {
should_try_gc = false;
} else {
// Read the GC count while still holding the Heap_lock.
gc_count_before = total_collections();
should_try_gc = true;
// The GCLocker may not be active but the GCLocker initiated
// GC may not yet have been performed (GCLocker::needs_gc()
// returns true). In this case we do not try this GC and
// wait until the GCLocker initiated GC is performed, and
// then retry the allocation.
if (GC_locker::needs_gc()) {
should_try_gc = false;
} else {
// Read the GC count while still holding the Heap_lock.
gc_count_before = total_collections();
should_try_gc = true;
}
}
}
@ -1081,6 +1102,9 @@ HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
return NULL;
}
} else {
// The GCLocker is either active or the GCLocker initiated
// GC has not yet been performed. Stall until it is and
// then retry the allocation.
GC_locker::stall_until_clear();
}