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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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71
hotspot/src/share/vm/memory/referenceProcessor.cpp
View file

@ -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
@ -102,40 +102,17 @@ void ReferenceProcessor::init_statics() {
"Unrecongnized RefDiscoveryPolicy");
}
ReferenceProcessor*
ReferenceProcessor::create_ref_processor(MemRegion span,
bool atomic_discovery,
bool mt_discovery,
BoolObjectClosure* is_alive_non_header,
int parallel_gc_threads,
bool mt_processing,
bool dl_needs_barrier) {
int mt_degree = 1;
if (parallel_gc_threads > 1) {
mt_degree = parallel_gc_threads;
}
ReferenceProcessor* rp =
new ReferenceProcessor(span, atomic_discovery,
mt_discovery, mt_degree,
mt_processing && (parallel_gc_threads > 0),
dl_needs_barrier);
if (rp == NULL) {
vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
}
rp->set_is_alive_non_header(is_alive_non_header);
rp->setup_policy(false /* default soft ref policy */);
return rp;
}
ReferenceProcessor::ReferenceProcessor(MemRegion span,
bool atomic_discovery,
bool mt_discovery,
int mt_degree,
bool mt_processing,
int mt_processing_degree,
bool mt_discovery,
int mt_discovery_degree,
bool atomic_discovery,
BoolObjectClosure* is_alive_non_header,
bool discovered_list_needs_barrier) :
_discovering_refs(false),
_enqueuing_is_done(false),
_is_alive_non_header(NULL),
_is_alive_non_header(is_alive_non_header),
_discovered_list_needs_barrier(discovered_list_needs_barrier),
_bs(NULL),
_processing_is_mt(mt_processing),
@ -144,8 +121,8 @@ ReferenceProcessor::ReferenceProcessor(MemRegion span,
_span = span;
_discovery_is_atomic = atomic_discovery;
_discovery_is_mt = mt_discovery;
_num_q = mt_degree;
_max_num_q = mt_degree;
_num_q = MAX2(1, mt_processing_degree);
_max_num_q = MAX2(_num_q, mt_discovery_degree);
_discoveredSoftRefs = NEW_C_HEAP_ARRAY(DiscoveredList, _max_num_q * subclasses_of_ref);
if (_discoveredSoftRefs == NULL) {
vm_exit_during_initialization("Could not allocated RefProc Array");
@ -163,6 +140,7 @@ ReferenceProcessor::ReferenceProcessor(MemRegion span,
if (discovered_list_needs_barrier) {
_bs = Universe::heap()->barrier_set();
}
setup_policy(false /* default soft ref policy */);
}
#ifndef PRODUCT
@ -405,15 +383,14 @@ public:
{ }
virtual void work(unsigned int work_id) {
assert(work_id < (unsigned int)_ref_processor.num_q(), "Index out-of-bounds");
assert(work_id < (unsigned int)_ref_processor.max_num_q(), "Index out-of-bounds");
// Simplest first cut: static partitioning.
int index = work_id;
// The increment on "index" must correspond to the maximum number of queues
// (n_queues) with which that ReferenceProcessor was created. That
// is because of the "clever" way the discovered references lists were
// allocated and are indexed into. That number is ParallelGCThreads
// currently. Assert that.
assert(_n_queues == (int) ParallelGCThreads, "Different number not expected");
// allocated and are indexed into.
assert(_n_queues == (int) _ref_processor.max_num_q(), "Different number not expected");
for (int j = 0;
j < subclasses_of_ref;
j++, index += _n_queues) {
@ -672,7 +649,7 @@ ReferenceProcessor::pp2_work(DiscoveredList& refs_list,
}
}
NOT_PRODUCT(
if (PrintGCDetails && TraceReferenceGC) {
if (PrintGCDetails && TraceReferenceGC && (iter.processed() > 0)) {
gclog_or_tty->print_cr(" Dropped %d active Refs out of %d "
"Refs in discovered list " INTPTR_FORMAT,
iter.removed(), iter.processed(), (address)refs_list.head());
@ -711,7 +688,7 @@ ReferenceProcessor::pp2_work_concurrent_discovery(DiscoveredList& refs_list,
// Now close the newly reachable set
complete_gc->do_void();
NOT_PRODUCT(
if (PrintGCDetails && TraceReferenceGC) {
if (PrintGCDetails && TraceReferenceGC && (iter.processed() > 0)) {
gclog_or_tty->print_cr(" Dropped %d active Refs out of %d "
"Refs in discovered list " INTPTR_FORMAT,
iter.removed(), iter.processed(), (address)refs_list.head());
@ -951,7 +928,7 @@ ReferenceProcessor::process_discovered_reflist(
}
if (PrintReferenceGC && PrintGCDetails) {
size_t total = 0;
for (int i = 0; i < _num_q; ++i) {
for (int i = 0; i < _max_num_q; ++i) {
total += refs_lists[i].length();
}
gclog_or_tty->print(", %u refs", total);
@ -967,7 +944,7 @@ ReferenceProcessor::process_discovered_reflist(
RefProcPhase1Task phase1(*this, refs_lists, policy, true /*marks_oops_alive*/);
task_executor->execute(phase1);
} else {
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
process_phase1(refs_lists[i], policy,
is_alive, keep_alive, complete_gc);
}
@ -983,7 +960,7 @@ ReferenceProcessor::process_discovered_reflist(
RefProcPhase2Task phase2(*this, refs_lists, !discovery_is_atomic() /*marks_oops_alive*/);
task_executor->execute(phase2);
} else {
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
process_phase2(refs_lists[i], is_alive, keep_alive, complete_gc);
}
}
@ -994,7 +971,7 @@ ReferenceProcessor::process_discovered_reflist(
RefProcPhase3Task phase3(*this, refs_lists, clear_referent, true /*marks_oops_alive*/);
task_executor->execute(phase3);
} else {
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
process_phase3(refs_lists[i], clear_referent,
is_alive, keep_alive, complete_gc);
}
@ -1008,7 +985,7 @@ void ReferenceProcessor::clean_up_discovered_references() {
// for (int j = 0; j < _num_q; j++) {
// int index = i * _max_num_q + j;
for (int i = 0; i < _max_num_q * subclasses_of_ref; i++) {
if (TraceReferenceGC && PrintGCDetails && ((i % _num_q) == 0)) {
if (TraceReferenceGC && PrintGCDetails && ((i % _max_num_q) == 0)) {
gclog_or_tty->print_cr(
"\nScrubbing %s discovered list of Null referents",
list_name(i));
@ -1350,7 +1327,7 @@ void ReferenceProcessor::preclean_discovered_references(
{
TraceTime tt("Preclean WeakReferences", PrintGCDetails && PrintReferenceGC,
false, gclog_or_tty);
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
if (yield->should_return()) {
return;
}
@ -1363,7 +1340,7 @@ void ReferenceProcessor::preclean_discovered_references(
{
TraceTime tt("Preclean FinalReferences", PrintGCDetails && PrintReferenceGC,
false, gclog_or_tty);
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
if (yield->should_return()) {
return;
}
@ -1376,7 +1353,7 @@ void ReferenceProcessor::preclean_discovered_references(
{
TraceTime tt("Preclean PhantomReferences", PrintGCDetails && PrintReferenceGC,
false, gclog_or_tty);
for (int i = 0; i < _num_q; i++) {
for (int i = 0; i < _max_num_q; i++) {
if (yield->should_return()) {
return;
}
@ -1433,7 +1410,7 @@ ReferenceProcessor::preclean_discovered_reflist(DiscoveredList& refs_list,
complete_gc->do_void();
NOT_PRODUCT(
if (PrintGCDetails && PrintReferenceGC) {
if (PrintGCDetails && PrintReferenceGC && (iter.processed() > 0)) {
gclog_or_tty->print_cr(" Dropped %d Refs out of %d "
"Refs in discovered list " INTPTR_FORMAT,
iter.removed(), iter.processed(), (address)refs_list.head());