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6668573: CMS: reference processing crash if ParallelCMSThreads > ParallelGCThreads

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Use _max_num_q = max(discovery_degree, processing_degree), and let balance_queues() redistribute from discovery_degree to processing_degree of queues. This should also allow a more dynamic and flexible parallelism policy in the future.

Reviewed-by: jmasa, johnc
This commit is contained in:
Y. Srinivas Ramakrishna 2011-03-17 10:32:46 -07:00
parent 7293fabc43
commit b4b287e7ac
13 changed files with 148 additions and 153 deletions
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38
hotspot/src/share/vm/memory/referenceProcessor.hpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -71,7 +71,7 @@ class ReferenceProcessor : public CHeapObj {
bool _enqueuing_is_done; // true if all weak references enqueued
bool _processing_is_mt; // true during phases when
// reference processing is MT.
int _next_id; // round-robin counter in
int _next_id; // round-robin mod _num_q counter in
// support of work distribution
// For collectors that do not keep GC marking information
@ -103,7 +103,8 @@ class ReferenceProcessor : public CHeapObj {
public:
int num_q() { return _num_q; }
void set_mt_degree(int v) { _num_q = v; }
int max_num_q() { return _max_num_q; }
void set_active_mt_degree(int v) { _num_q = v; }
DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
static oop sentinel_ref() { return _sentinelRef; }
static oop* adr_sentinel_ref() { return &_sentinelRef; }
@ -216,6 +217,7 @@ class ReferenceProcessor : public CHeapObj {
VoidClosure* complete_gc,
YieldClosure* yield);
// round-robin mod _num_q (not: _not_ mode _max_num_q)
int next_id() {
int id = _next_id;
if (++_next_id == _num_q) {
@ -256,24 +258,16 @@ class ReferenceProcessor : public CHeapObj {
_max_num_q(0),
_processing_is_mt(false),
_next_id(0)
{}
{ }
ReferenceProcessor(MemRegion span, bool atomic_discovery,
bool mt_discovery,
int mt_degree = 1,
bool mt_processing = false,
// Default parameters give you a vanilla reference processor.
ReferenceProcessor(MemRegion span,
bool mt_processing = false, int mt_processing_degree = 1,
bool mt_discovery = false, int mt_discovery_degree = 1,
bool atomic_discovery = true,
BoolObjectClosure* is_alive_non_header = NULL,
bool discovered_list_needs_barrier = false);
// Allocates and initializes a reference processor.
static ReferenceProcessor* create_ref_processor(
MemRegion span,
bool atomic_discovery,
bool mt_discovery,
BoolObjectClosure* is_alive_non_header = NULL,
int parallel_gc_threads = 1,
bool mt_processing = false,
bool discovered_list_needs_barrier = false);
// RefDiscoveryPolicy values
enum DiscoveryPolicy {
ReferenceBasedDiscovery = 0,
@ -397,20 +391,20 @@ class ReferenceProcessorSpanMutator: StackObj {
// A utility class to temporarily change the MT'ness of
// reference discovery for the given ReferenceProcessor
// in the scope that contains it.
class ReferenceProcessorMTMutator: StackObj {
class ReferenceProcessorMTDiscoveryMutator: StackObj {
private:
ReferenceProcessor* _rp;
bool _saved_mt;
public:
ReferenceProcessorMTMutator(ReferenceProcessor* rp,
bool mt):
ReferenceProcessorMTDiscoveryMutator(ReferenceProcessor* rp,
bool mt):
_rp(rp) {
_saved_mt = _rp->discovery_is_mt();
_rp->set_mt_discovery(mt);
}
~ReferenceProcessorMTMutator() {
~ReferenceProcessorMTDiscoveryMutator() {
_rp->set_mt_discovery(_saved_mt);
}
};