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8049421: G1 Class Unloading after completing a concurrent mark cycle

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Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
This commit is contained in:
Stefan Karlsson 2014-07-07 10:12:40 +02:00
parent ef1e9b3c80
commit 1b001a2afd
75 changed files with 2169 additions and 874 deletions
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138
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
View file

@ -1558,11 +1558,11 @@ bool CMSCollector::shouldConcurrentCollect() {
}
if (MetaspaceGC::should_concurrent_collect()) {
if (Verbose && PrintGCDetails) {
if (Verbose && PrintGCDetails) {
gclog_or_tty->print("CMSCollector: collect for metadata allocation ");
}
return true;
}
return true;
}
// CMSTriggerInterval starts a CMS cycle if enough time has passed.
if (CMSTriggerInterval >= 0) {
@ -2997,20 +2997,21 @@ void CMSCollector::verify_after_remark_work_1() {
HandleMark hm;
GenCollectedHeap* gch = GenCollectedHeap::heap();
// Get a clear set of claim bits for the strong roots processing to work with.
// Get a clear set of claim bits for the roots processing to work with.
ClassLoaderDataGraph::clear_claimed_marks();
// Mark from roots one level into CMS
MarkRefsIntoClosure notOlder(_span, verification_mark_bm());
gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
gch->gen_process_strong_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
&notOlder,
NULL,
NULL); // SSS: Provide correct closure
gch->gen_process_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
should_unload_classes(),
&notOlder,
NULL,
NULL); // SSS: Provide correct closure
// Now mark from the roots
MarkFromRootsClosure markFromRootsClosure(this, _span,
@ -3061,22 +3062,24 @@ void CMSCollector::verify_after_remark_work_2() {
HandleMark hm;
GenCollectedHeap* gch = GenCollectedHeap::heap();
// Get a clear set of claim bits for the strong roots processing to work with.
// Get a clear set of claim bits for the roots processing to work with.
ClassLoaderDataGraph::clear_claimed_marks();
// Mark from roots one level into CMS
MarkRefsIntoVerifyClosure notOlder(_span, verification_mark_bm(),
markBitMap());
KlassToOopClosure klass_closure(&notOlder);
CLDToOopClosure cld_closure(&notOlder, true);
gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
gch->gen_process_strong_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
&notOlder,
NULL,
&klass_closure);
gch->gen_process_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
should_unload_classes(),
&notOlder,
NULL,
&cld_closure);
// Now mark from the roots
MarkFromRootsVerifyClosure markFromRootsClosure(this, _span,
@ -3263,12 +3266,10 @@ bool ConcurrentMarkSweepGeneration::is_too_full() const {
void CMSCollector::setup_cms_unloading_and_verification_state() {
const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC
|| VerifyBeforeExit;
const int rso = SharedHeap::SO_Strings | SharedHeap::SO_AllCodeCache;
const int rso = SharedHeap::SO_AllCodeCache;
// We set the proper root for this CMS cycle here.
if (should_unload_classes()) { // Should unload classes this cycle
remove_root_scanning_option(SharedHeap::SO_AllClasses);
add_root_scanning_option(SharedHeap::SO_SystemClasses);
remove_root_scanning_option(rso); // Shrink the root set appropriately
set_verifying(should_verify); // Set verification state for this cycle
return; // Nothing else needs to be done at this time
@ -3276,8 +3277,6 @@ void CMSCollector::setup_cms_unloading_and_verification_state() {
// Not unloading classes this cycle
assert(!should_unload_classes(), "Inconsistency!");
remove_root_scanning_option(SharedHeap::SO_SystemClasses);
add_root_scanning_option(SharedHeap::SO_AllClasses);
if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) {
// Include symbols, strings and code cache elements to prevent their resurrection.
@ -3685,15 +3684,16 @@ void CMSCollector::checkpointRootsInitialWork(bool asynch) {
gch->set_par_threads(0);
} else {
// The serial version.
KlassToOopClosure klass_closure(&notOlder);
CLDToOopClosure cld_closure(&notOlder, true);
gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
gch->gen_process_strong_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
&notOlder,
NULL,
&klass_closure);
gch->gen_process_roots(_cmsGen->level(),
true, // younger gens are roots
true, // activate StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
should_unload_classes(),
&notOlder,
NULL,
&cld_closure);
}
}
@ -5139,7 +5139,6 @@ void CMSParInitialMarkTask::work(uint worker_id) {
_timer.start();
GenCollectedHeap* gch = GenCollectedHeap::heap();
Par_MarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap));
KlassToOopClosure klass_closure(&par_mri_cl);
// ---------- young gen roots --------------
{
@ -5155,13 +5154,17 @@ void CMSParInitialMarkTask::work(uint worker_id) {
// ---------- remaining roots --------------
_timer.reset();
_timer.start();
gch->gen_process_strong_roots(_collector->_cmsGen->level(),
false, // yg was scanned above
false, // this is parallel code
SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
&par_mri_cl,
NULL,
&klass_closure);
CLDToOopClosure cld_closure(&par_mri_cl, true);
gch->gen_process_roots(_collector->_cmsGen->level(),
false, // yg was scanned above
false, // this is parallel code
SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
_collector->should_unload_classes(),
&par_mri_cl,
NULL,
&cld_closure);
assert(_collector->should_unload_classes()
|| (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_AllCodeCache),
"if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops");
@ -5290,13 +5293,15 @@ void CMSParRemarkTask::work(uint worker_id) {
// ---------- remaining roots --------------
_timer.reset();
_timer.start();
gch->gen_process_strong_roots(_collector->_cmsGen->level(),
false, // yg was scanned above
false, // this is parallel code
SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
&par_mrias_cl,
NULL,
NULL); // The dirty klasses will be handled below
gch->gen_process_roots(_collector->_cmsGen->level(),
false, // yg was scanned above
false, // this is parallel code
SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
_collector->should_unload_classes(),
&par_mrias_cl,
NULL,
NULL); // The dirty klasses will be handled below
assert(_collector->should_unload_classes()
|| (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_AllCodeCache),
"if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops");
@ -5351,7 +5356,7 @@ void CMSParRemarkTask::work(uint worker_id) {
// We might have added oops to ClassLoaderData::_handles during the
// concurrent marking phase. These oops point to newly allocated objects
// that are guaranteed to be kept alive. Either by the direct allocation
// code, or when the young collector processes the strong roots. Hence,
// code, or when the young collector processes the roots. Hence,
// we don't have to revisit the _handles block during the remark phase.
// ---------- rescan dirty cards ------------
@ -5773,7 +5778,7 @@ void CMSCollector::do_remark_parallel() {
cms_space,
n_workers, workers, task_queues());
// Set up for parallel process_strong_roots work.
// Set up for parallel process_roots work.
gch->set_par_threads(n_workers);
// We won't be iterating over the cards in the card table updating
// the younger_gen cards, so we shouldn't call the following else
@ -5782,7 +5787,7 @@ void CMSCollector::do_remark_parallel() {
// gch->rem_set()->prepare_for_younger_refs_iterate(true); // parallel
// The young gen rescan work will not be done as part of
// process_strong_roots (which currently doesn't knw how to
// process_roots (which currently doesn't know how to
// parallelize such a scan), but rather will be broken up into
// a set of parallel tasks (via the sampling that the [abortable]
// preclean phase did of EdenSpace, plus the [two] tasks of
@ -5879,13 +5884,15 @@ void CMSCollector::do_remark_non_parallel() {
gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
GenCollectedHeap::StrongRootsScope srs(gch);
gch->gen_process_strong_roots(_cmsGen->level(),
true, // younger gens as roots
false, // use the local StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
&mrias_cl,
NULL,
NULL); // The dirty klasses will be handled below
gch->gen_process_roots(_cmsGen->level(),
true, // younger gens as roots
false, // use the local StrongRootsScope
SharedHeap::ScanningOption(roots_scanning_options()),
should_unload_classes(),
&mrias_cl,
NULL,
NULL); // The dirty klasses will be handled below
assert(should_unload_classes()
|| (roots_scanning_options() & SharedHeap::SO_AllCodeCache),
@ -5925,7 +5932,7 @@ void CMSCollector::do_remark_non_parallel() {
// We might have added oops to ClassLoaderData::_handles during the
// concurrent marking phase. These oops point to newly allocated objects
// that are guaranteed to be kept alive. Either by the direct allocation
// code, or when the young collector processes the strong roots. Hence,
// code, or when the young collector processes the roots. Hence,
// we don't have to revisit the _handles block during the remark phase.
verify_work_stacks_empty();
@ -6175,15 +6182,14 @@ void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) {
// Clean up unreferenced symbols in symbol table.
SymbolTable::unlink();
}
{
GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
// Delete entries for dead interned strings.
StringTable::unlink(&_is_alive_closure);
}
}
// CMS doesn't use the StringTable as hard roots when class unloading is turned off.
// Need to check if we really scanned the StringTable.
if ((roots_scanning_options() & SharedHeap::SO_Strings) == 0) {
GCTraceTime t("scrub string table", PrintGCDetails, false, _gc_timer_cm, _gc_tracer_cm->gc_id());
// Delete entries for dead interned strings.
StringTable::unlink(&_is_alive_closure);
}
// Restore any preserved marks as a result of mark stack or
// work queue overflow