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6684579: SoftReference processing can be made more efficient

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For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.

Reviewed-by: jmasa
This commit is contained in:
Y. Srinivas Ramakrishna 2008-11-20 16:56:09 -08:00
parent db6bef2c70
commit 7d7cf3f8af
18 changed files with 137 additions and 164 deletions
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24
hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp
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@ -811,6 +811,7 @@ void ConcurrentMark::checkpointRootsInitialPost() {
ReferenceProcessor* rp = g1h->ref_processor();
rp->verify_no_references_recorded();
rp->enable_discovery(); // enable ("weak") refs discovery
rp->snap_policy(false); // snapshot the soft ref policy to be used in this cycle
SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
satb_mq_set.set_process_completed_threshold(G1SATBProcessCompletedThreshold);
@ -1829,32 +1830,21 @@ class G1CMDrainMarkingStackClosure: public VoidClosure {
void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
ResourceMark rm;
HandleMark hm;
ReferencePolicy* soft_ref_policy;
G1CollectedHeap* g1h = G1CollectedHeap::heap();
ReferenceProcessor* rp = g1h->ref_processor();
// Process weak references.
if (clear_all_soft_refs) {
soft_ref_policy = new AlwaysClearPolicy();
} else {
#ifdef COMPILER2
soft_ref_policy = new LRUMaxHeapPolicy();
#else
soft_ref_policy = new LRUCurrentHeapPolicy();
#endif
}
rp->snap_policy(clear_all_soft_refs);
assert(_markStack.isEmpty(), "mark stack should be empty");
G1CollectedHeap* g1 = G1CollectedHeap::heap();
G1CMIsAliveClosure g1IsAliveClosure(g1);
G1CMKeepAliveClosure g1KeepAliveClosure(g1, this, nextMarkBitMap());
G1CMIsAliveClosure g1IsAliveClosure (g1h);
G1CMKeepAliveClosure g1KeepAliveClosure(g1h, this, nextMarkBitMap());
G1CMDrainMarkingStackClosure
g1DrainMarkingStackClosure(nextMarkBitMap(), &_markStack,
&g1KeepAliveClosure);
// XXXYYY Also: copy the parallel ref processing code from CMS.
ReferenceProcessor* rp = g1->ref_processor();
rp->process_discovered_references(soft_ref_policy,
&g1IsAliveClosure,
rp->process_discovered_references(&g1IsAliveClosure,
&g1KeepAliveClosure,
&g1DrainMarkingStackClosure,
NULL);