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提交 0ce87a38 编写于 作者: T tonyp
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上级 0838dcdc f903d5a1
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Showing with 198 addition and 109 deletion
src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
浏览文件 @ 0ce87a38
......@@ -225,6 +225,34 @@ ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration(
assert(_dilatation_factor >= 1.0, "from previous assert");
}
// The field "_initiating_occupancy" represents the occupancy percentage
// at which we trigger a new collection cycle. Unless explicitly specified
// via CMSInitiating[Perm]OccupancyFraction (argument "io" below), it
// is calculated by:
//
// Let "f" be MinHeapFreeRatio in
//
// _intiating_occupancy = 100-f +
// f * (CMSTrigger[Perm]Ratio/100)
// where CMSTrigger[Perm]Ratio is the argument "tr" below.
//
// That is, if we assume the heap is at its desired maximum occupancy at the
// end of a collection, we let CMSTrigger[Perm]Ratio of the (purported) free
// space be allocated before initiating a new collection cycle.
//
void ConcurrentMarkSweepGeneration::init_initiating_occupancy(intx io, intx tr) {
assert(io <= 100 && tr >= 0 && tr <= 100, "Check the arguments");
if (io >= 0) {
_initiating_occupancy = (double)io / 100.0;
} else {
_initiating_occupancy = ((100 - MinHeapFreeRatio) +
(double)(tr * MinHeapFreeRatio) / 100.0)
/ 100.0;
}
}
void ConcurrentMarkSweepGeneration::ref_processor_init() {
assert(collector() != NULL, "no collector");
collector()->ref_processor_init();
......@@ -520,8 +548,8 @@ CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
_verification_mark_bm(0, Mutex::leaf + 1, "CMS_verification_mark_bm_lock"),
_completed_initialization(false),
_collector_policy(cp),
_unload_classes(false),
_unloaded_classes_last_cycle(false),
_should_unload_classes(false),
_concurrent_cycles_since_last_unload(0),
_sweep_estimate(CMS_SweepWeight, CMS_SweepPadding)
{
if (ExplicitGCInvokesConcurrentAndUnloadsClasses) {
......@@ -642,26 +670,11 @@ CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
}
}
// "initiatingOccupancy" is the occupancy ratio at which we trigger
// a new collection cycle. Unless explicitly specified via
// CMSTriggerRatio, it is calculated by:
// Let "f" be MinHeapFreeRatio in
//
// intiatingOccupancy = 100-f +
// f * (CMSTriggerRatio/100)
// That is, if we assume the heap is at its desired maximum occupancy at the
// end of a collection, we let CMSTriggerRatio of the (purported) free
// space be allocated before initiating a new collection cycle.
if (CMSInitiatingOccupancyFraction > 0) {
_initiatingOccupancy = (double)CMSInitiatingOccupancyFraction / 100.0;
} else {
_initiatingOccupancy = ((100 - MinHeapFreeRatio) +
(double)(CMSTriggerRatio *
MinHeapFreeRatio) / 100.0)
/ 100.0;
}
_cmsGen ->init_initiating_occupancy(CMSInitiatingOccupancyFraction, CMSTriggerRatio);
_permGen->init_initiating_occupancy(CMSInitiatingPermOccupancyFraction, CMSTriggerPermRatio);
// Clip CMSBootstrapOccupancy between 0 and 100.
_bootstrap_occupancy = ((double)MIN2((intx)100, MAX2((intx)0, CMSBootstrapOccupancy)))
_bootstrap_occupancy = ((double)MIN2((uintx)100, MAX2((uintx)0, CMSBootstrapOccupancy)))
/(double)100;
_full_gcs_since_conc_gc = 0;
......@@ -1413,7 +1426,8 @@ bool CMSCollector::shouldConcurrentCollect() {
gclog_or_tty->print_cr("promotion_rate=%g", stats().promotion_rate());
gclog_or_tty->print_cr("cms_allocation_rate=%g", stats().cms_allocation_rate());
gclog_or_tty->print_cr("occupancy=%3.7f", _cmsGen->occupancy());
gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", initiatingOccupancy());
gclog_or_tty->print_cr("initiatingOccupancy=%3.7f", _cmsGen->initiating_occupancy());
gclog_or_tty->print_cr("initiatingPermOccupancy=%3.7f", _permGen->initiating_occupancy());
}
// ------------------------------------------------------------------
......@@ -1446,22 +1460,36 @@ bool CMSCollector::shouldConcurrentCollect() {
// old gen want a collection cycle started. Each may use
// an appropriate criterion for making this decision.
// XXX We need to make sure that the gen expansion
// criterion dovetails well with this.
if (_cmsGen->shouldConcurrentCollect(initiatingOccupancy())) {
// criterion dovetails well with this. XXX NEED TO FIX THIS
if (_cmsGen->should_concurrent_collect()) {
if (Verbose && PrintGCDetails) {
gclog_or_tty->print_cr("CMS old gen initiated");
}
return true;
}
if (cms_should_unload_classes() &&
_permGen->shouldConcurrentCollect(initiatingOccupancy())) {
if (Verbose && PrintGCDetails) {
gclog_or_tty->print_cr("CMS perm gen initiated");
// We start a collection if we believe an incremental collection may fail;
// this is not likely to be productive in practice because it's probably too
// late anyway.
GenCollectedHeap* gch = GenCollectedHeap::heap();
assert(gch->collector_policy()->is_two_generation_policy(),
"You may want to check the correctness of the following");
if (gch->incremental_collection_will_fail()) {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print("CMSCollector: collect because incremental collection will fail ");
}
return true;
}
if (CMSClassUnloadingEnabled && _permGen->should_concurrent_collect()) {
bool res = update_should_unload_classes();
if (res) {
if (Verbose && PrintGCDetails) {
gclog_or_tty->print_cr("CMS perm gen initiated");
}
return true;
}
}
return false;
}
......@@ -1471,32 +1499,36 @@ void CMSCollector::clear_expansion_cause() {
_permGen->clear_expansion_cause();
}
bool ConcurrentMarkSweepGeneration::shouldConcurrentCollect(
double initiatingOccupancy) {
// We should be conservative in starting a collection cycle. To
// start too eagerly runs the risk of collecting too often in the
// extreme. To collect too rarely falls back on full collections,
// which works, even if not optimum in terms of concurrent work.
// As a work around for too eagerly collecting, use the flag
// UseCMSInitiatingOccupancyOnly. This also has the advantage of
// giving the user an easily understandable way of controlling the
// collections.
// We want to start a new collection cycle if any of the following
// conditions hold:
// . our current occupancy exceeds the initiating occupancy, or
// . we recently needed to expand and have not since that expansion,
// collected, or
// . we are not using adaptive free lists and linear allocation is
// going to fail, or
// . (for old gen) incremental collection has already failed or
// may soon fail in the near future as we may not be able to absorb
// promotions.
assert_lock_strong(freelistLock());
// We should be conservative in starting a collection cycle. To
// start too eagerly runs the risk of collecting too often in the
// extreme. To collect too rarely falls back on full collections,
// which works, even if not optimum in terms of concurrent work.
// As a work around for too eagerly collecting, use the flag
// UseCMSInitiatingOccupancyOnly. This also has the advantage of
// giving the user an easily understandable way of controlling the
// collections.
// We want to start a new collection cycle if any of the following
// conditions hold:
// . our current occupancy exceeds the configured initiating occupancy
// for this generation, or
// . we recently needed to expand this space and have not, since that
// expansion, done a collection of this generation, or
// . the underlying space believes that it may be a good idea to initiate
// a concurrent collection (this may be based on criteria such as the
// following: the space uses linear allocation and linear allocation is
// going to fail, or there is believed to be excessive fragmentation in
// the generation, etc... or ...
// [.(currently done by CMSCollector::shouldConcurrentCollect() only for
// the case of the old generation, not the perm generation; see CR 6543076):
// we may be approaching a point at which allocation requests may fail because
// we will be out of sufficient free space given allocation rate estimates.]
bool ConcurrentMarkSweepGeneration::should_concurrent_collect() const {
if (occupancy() > initiatingOccupancy) {
assert_lock_strong(freelistLock());
if (occupancy() > initiating_occupancy()) {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(" %s: collect because of occupancy %f / %f ",
short_name(), occupancy(), initiatingOccupancy);
short_name(), occupancy(), initiating_occupancy());
}
return true;
}
......@@ -1510,20 +1542,9 @@ bool ConcurrentMarkSweepGeneration::shouldConcurrentCollect(
}
return true;
}
GenCollectedHeap* gch = GenCollectedHeap::heap();
assert(gch->collector_policy()->is_two_generation_policy(),
"You may want to check the correctness of the following");
if (gch->incremental_collection_will_fail()) {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(" %s: collect because incremental collection will fail ",
short_name());
}
return true;
}
if (!_cmsSpace->adaptive_freelists() &&
_cmsSpace->linearAllocationWouldFail()) {
if (_cmsSpace->should_concurrent_collect()) {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print(" %s: collect because of linAB ",
gclog_or_tty->print(" %s: collect because cmsSpace says so ",
short_name());
}
return true;
......@@ -1970,8 +1991,9 @@ void CMSCollector::do_compaction_work(bool clear_all_soft_refs) {
"Should have been NULL'd before baton was passed");
reset(false /* == !asynch */);
_cmsGen->reset_after_compaction();
_concurrent_cycles_since_last_unload = 0;
if (verifying() && !cms_should_unload_classes()) {
if (verifying() && !should_unload_classes()) {
perm_gen_verify_bit_map()->clear_all();
}
......@@ -2098,6 +2120,7 @@ void CMSCollector::collect_in_background(bool clear_all_soft_refs) {
{
bool safepoint_check = Mutex::_no_safepoint_check_flag;
MutexLockerEx hl(Heap_lock, safepoint_check);
FreelistLocker fll(this);
MutexLockerEx x(CGC_lock, safepoint_check);
if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) {
// The foreground collector is active or we're
......@@ -2112,13 +2135,9 @@ void CMSCollector::collect_in_background(bool clear_all_soft_refs) {
// a new cycle.
clear_expansion_cause();
}
_unloaded_classes_last_cycle = cms_should_unload_classes(); // ... from last cycle
// This controls class unloading in response to an explicit gc request.
// If ExplicitGCInvokesConcurrentAndUnloadsClasses is set, then
// we will unload classes even if CMSClassUnloadingEnabled is not set.
// See CR 6541037 and related CRs.
_unload_classes = _full_gc_requested // ... for this cycle
&& ExplicitGCInvokesConcurrentAndUnloadsClasses;
// Decide if we want to enable class unloading as part of the
// ensuing concurrent GC cycle.
update_should_unload_classes();
_full_gc_requested = false; // acks all outstanding full gc requests
// Signal that we are about to start a collection
gch->increment_total_full_collections(); // ... starting a collection cycle
......@@ -3047,21 +3066,62 @@ void CMSCollector::verify_overflow_empty() const {
}
#endif // PRODUCT
// Decide if we want to enable class unloading as part of the
// ensuing concurrent GC cycle. We will collect the perm gen and
// unload classes if it's the case that:
// (1) an explicit gc request has been made and the flag
// ExplicitGCInvokesConcurrentAndUnloadsClasses is set, OR
// (2) (a) class unloading is enabled at the command line, and
// (b) (i) perm gen threshold has been crossed, or
// (ii) old gen is getting really full, or
// (iii) the previous N CMS collections did not collect the
// perm gen
// NOTE: Provided there is no change in the state of the heap between
// calls to this method, it should have idempotent results. Moreover,
// its results should be monotonically increasing (i.e. going from 0 to 1,
// but not 1 to 0) between successive calls between which the heap was
// not collected. For the implementation below, it must thus rely on
// the property that concurrent_cycles_since_last_unload()
// will not decrease unless a collection cycle happened and that
// _permGen->should_concurrent_collect() and _cmsGen->is_too_full() are
// themselves also monotonic in that sense. See check_monotonicity()
// below.
bool CMSCollector::update_should_unload_classes() {
_should_unload_classes = false;
// Condition 1 above
if (_full_gc_requested && ExplicitGCInvokesConcurrentAndUnloadsClasses) {
_should_unload_classes = true;
} else if (CMSClassUnloadingEnabled) { // Condition 2.a above
// Disjuncts 2.b.(i,ii,iii) above
_should_unload_classes = (concurrent_cycles_since_last_unload() >=
CMSClassUnloadingMaxInterval)
|| _permGen->should_concurrent_collect()
|| _cmsGen->is_too_full();
}
return _should_unload_classes;
}
bool ConcurrentMarkSweepGeneration::is_too_full() const {
bool res = should_concurrent_collect();
res = res && (occupancy() > (double)CMSIsTooFullPercentage/100.0);
return res;
}
void CMSCollector::setup_cms_unloading_and_verification_state() {
const bool should_verify = VerifyBeforeGC || VerifyAfterGC || VerifyDuringGC
|| VerifyBeforeExit;
const int rso = SharedHeap::SO_Symbols | SharedHeap::SO_Strings
| SharedHeap::SO_CodeCache;
if (cms_should_unload_classes()) { // Should unload classes this cycle
if (should_unload_classes()) { // Should unload classes this cycle
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
}
// Not unloading classes this cycle
assert(!cms_should_unload_classes(), "Inconsitency!");
if ((!verifying() || cms_unloaded_classes_last_cycle()) && should_verify) {
assert(!should_unload_classes(), "Inconsitency!");
if ((!verifying() || unloaded_classes_last_cycle()) && should_verify) {
// We were not verifying, or we _were_ unloading classes in the last cycle,
// AND some verification options are enabled this cycle; in this case,
// we must make sure that the deadness map is allocated if not already so,
......@@ -4693,7 +4753,7 @@ void CMSCollector::checkpointRootsFinalWork(bool asynch,
GenCollectedHeap* gch = GenCollectedHeap::heap();
if (cms_should_unload_classes()) {
if (should_unload_classes()) {
CodeCache::gc_prologue();
}
assert(haveFreelistLocks(), "must have free list locks");
......@@ -4753,7 +4813,7 @@ void CMSCollector::checkpointRootsFinalWork(bool asynch,
verify_work_stacks_empty();
verify_overflow_empty();
if (cms_should_unload_classes()) {
if (should_unload_classes()) {
CodeCache::gc_epilogue();
}
......@@ -5623,7 +5683,7 @@ void CMSCollector::refProcessingWork(bool asynch, bool clear_all_soft_refs) {
verify_work_stacks_empty();
}
if (cms_should_unload_classes()) {
if (should_unload_classes()) {
{
TraceTime t("class unloading", PrintGCDetails, false, gclog_or_tty);
......@@ -5726,7 +5786,7 @@ void CMSCollector::sweep(bool asynch) {
// this cycle, we preserve the perm gen object "deadness" information
// in the perm_gen_verify_bit_map. In order to do that we traverse
// all blocks in perm gen and mark all dead objects.
if (verifying() && !cms_should_unload_classes()) {
if (verifying() && !should_unload_classes()) {
assert(perm_gen_verify_bit_map()->sizeInBits() != 0,
"Should have already been allocated");
MarkDeadObjectsClosure mdo(this, _permGen->cmsSpace(),
......@@ -5753,7 +5813,7 @@ void CMSCollector::sweep(bool asynch) {
}
// Now repeat for perm gen
if (cms_should_unload_classes()) {
if (should_unload_classes()) {
CMSTokenSyncWithLocks ts(true, _permGen->freelistLock(),
bitMapLock());
sweepWork(_permGen, asynch);
......@@ -5775,7 +5835,7 @@ void CMSCollector::sweep(bool asynch) {
// already have needed locks
sweepWork(_cmsGen, asynch);
if (cms_should_unload_classes()) {
if (should_unload_classes()) {
sweepWork(_permGen, asynch);
}
// Update heap occupancy information which is used as
......@@ -5937,6 +5997,11 @@ void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* gen,
}
gen->cmsSpace()->sweep_completed();
gen->cmsSpace()->endSweepFLCensus(sweepCount());
if (should_unload_classes()) { // unloaded classes this cycle,
_concurrent_cycles_since_last_unload = 0; // ... reset count
} else { // did not unload classes,
_concurrent_cycles_since_last_unload++; // ... increment count
}
}
// Reset CMS data structures (for now just the marking bit map)
......@@ -7194,7 +7259,7 @@ PushOrMarkClosure::PushOrMarkClosure(CMSCollector* collector,
_revisitStack(revisitStack),
_finger(finger),
_parent(parent),
_should_remember_klasses(collector->cms_should_unload_classes())
_should_remember_klasses(collector->should_unload_classes())
{ }
Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector,
......@@ -7217,7 +7282,7 @@ Par_PushOrMarkClosure::Par_PushOrMarkClosure(CMSCollector* collector,
_finger(finger),
_global_finger_addr(global_finger_addr),
_parent(parent),
_should_remember_klasses(collector->cms_should_unload_classes())
_should_remember_klasses(collector->should_unload_classes())
{ }
......@@ -7360,7 +7425,7 @@ PushAndMarkClosure::PushAndMarkClosure(CMSCollector* collector,
_mark_stack(mark_stack),
_revisit_stack(revisit_stack),
_concurrent_precleaning(concurrent_precleaning),
_should_remember_klasses(collector->cms_should_unload_classes())
_should_remember_klasses(collector->should_unload_classes())
{
assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL");
}
......@@ -7422,7 +7487,7 @@ Par_PushAndMarkClosure::Par_PushAndMarkClosure(CMSCollector* collector,
_bit_map(bit_map),
_work_queue(work_queue),
_revisit_stack(revisit_stack),
_should_remember_klasses(collector->cms_should_unload_classes())
_should_remember_klasses(collector->should_unload_classes())
{
assert(_ref_processor != NULL, "_ref_processor shouldn't be NULL");
}
......@@ -7944,7 +8009,7 @@ size_t SweepClosure::doLiveChunk(FreeChunk* fc) {
#ifdef DEBUG
if (oop(addr)->klass() != NULL &&
( !_collector->cms_should_unload_classes()
( !_collector->should_unload_classes()
|| oop(addr)->is_parsable())) {
// Ignore mark word because we are running concurrent with mutators
assert(oop(addr)->is_oop(true), "live block should be an oop");
......@@ -7957,7 +8022,7 @@ size_t SweepClosure::doLiveChunk(FreeChunk* fc) {
} else {
// This should be an initialized object that's alive.
assert(oop(addr)->klass() != NULL &&
(!_collector->cms_should_unload_classes()
(!_collector->should_unload_classes()
|| oop(addr)->is_parsable()),
"Should be an initialized object");
// Ignore mark word because we are running concurrent with mutators
......
src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp
浏览文件 @ 0ce87a38
......@@ -535,13 +535,16 @@ class CMSCollector: public CHeapObj {
// In support of ExplicitGCInvokesConcurrent
static bool _full_gc_requested;
unsigned int _collection_count_start;
// Should we unload classes this concurrent cycle?
// Set in response to a concurrent full gc request.
bool _unload_classes;
bool _unloaded_classes_last_cycle;
bool _should_unload_classes;
unsigned int _concurrent_cycles_since_last_unload;
unsigned int concurrent_cycles_since_last_unload() const {
return _concurrent_cycles_since_last_unload;
}
// Did we (allow) unload classes in the previous concurrent cycle?
bool cms_unloaded_classes_last_cycle() const {
return _unloaded_classes_last_cycle || CMSClassUnloadingEnabled;
bool unloaded_classes_last_cycle() const {
return concurrent_cycles_since_last_unload() == 0;
}
// Verification support
......@@ -651,8 +654,6 @@ class CMSCollector: public CHeapObj {
// number of full gc's since the last concurrent gc.
uint _full_gcs_since_conc_gc;
// if occupancy exceeds this, start a new gc cycle
double _initiatingOccupancy;
// occupancy used for bootstrapping stats
double _bootstrap_occupancy;
......@@ -825,7 +826,6 @@ class CMSCollector: public CHeapObj {
Mutex* bitMapLock() const { return _markBitMap.lock(); }
static CollectorState abstract_state() { return _collectorState; }
double initiatingOccupancy() const { return _initiatingOccupancy; }
bool should_abort_preclean() const; // Whether preclean should be aborted.
size_t get_eden_used() const;
......@@ -849,11 +849,10 @@ class CMSCollector: public CHeapObj {
// In support of ExplicitGCInvokesConcurrent
static void request_full_gc(unsigned int full_gc_count);
// Should we unload classes in a particular concurrent cycle?
bool cms_should_unload_classes() const {
assert(!_unload_classes || ExplicitGCInvokesConcurrentAndUnloadsClasses,
"Inconsistency; see CR 6541037");
return _unload_classes || CMSClassUnloadingEnabled;
bool should_unload_classes() const {
return _should_unload_classes;
}
bool update_should_unload_classes();
void direct_allocated(HeapWord* start, size_t size);
......@@ -1022,6 +1021,10 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
_incremental_collection_failed = false;
}
// accessors
void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;}
CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; }
private:
// For parallel young-gen GC support.
CMSParGCThreadState** _par_gc_thread_states;
......@@ -1029,10 +1032,6 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
// Reason generation was expanded
CMSExpansionCause::Cause _expansion_cause;
// accessors
void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;}
CMSExpansionCause::Cause expansion_cause() { return _expansion_cause; }
// In support of MinChunkSize being larger than min object size
const double _dilatation_factor;
......@@ -1045,6 +1044,10 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
CollectionTypes _debug_collection_type;
// Fraction of current occupancy at which to start a CMS collection which
// will collect this generation (at least).
double _initiating_occupancy;
protected:
// Grow generation by specified size (returns false if unable to grow)
bool grow_by(size_t bytes);
......@@ -1060,6 +1063,10 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
// space.
size_t max_available() const;
// getter and initializer for _initiating_occupancy field.
double initiating_occupancy() const { return _initiating_occupancy; }
void init_initiating_occupancy(intx io, intx tr);
public:
ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size,
int level, CardTableRS* ct,
......@@ -1103,7 +1110,7 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
size_t capacity() const;
size_t used() const;
size_t free() const;
double occupancy() { return ((double)used())/((double)capacity()); }
double occupancy() const { return ((double)used())/((double)capacity()); }
size_t contiguous_available() const;
size_t unsafe_max_alloc_nogc() const;
......@@ -1158,8 +1165,8 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
bool younger_handles_promotion_failure) const;
bool should_collect(bool full, size_t size, bool tlab);
// XXXPERM
bool shouldConcurrentCollect(double initiatingOccupancy); // XXXPERM
virtual bool should_concurrent_collect() const;
virtual bool is_too_full() const;
void collect(bool full,
bool clear_all_soft_refs,
size_t size,
......
src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp
浏览文件 @ 0ce87a38
......@@ -267,7 +267,7 @@ inline bool CMSCollector::is_dead_obj(oop obj) const {
(_permGen->cmsSpace()->is_in_reserved(addr)
&& _permGen->cmsSpace()->block_is_obj(addr)),
"must be object");
return cms_should_unload_classes() &&
return should_unload_classes() &&
_collectorState == Sweeping &&
!_markBitMap.isMarked(addr);
}
......
src/share/vm/runtime/globals.hpp
浏览文件 @ 0ce87a38
......@@ -1319,6 +1319,10 @@ class CommandLineFlags {
product(bool, CMSClassUnloadingEnabled, false, \
"Whether class unloading enabled when using CMS GC") \
\
product(uintx, CMSClassUnloadingMaxInterval, 0, \
"When CMS class unloading is enabled, the maximum CMS cycle count"\
" for which classes may not be unloaded") \
\
product(bool, CMSCompactWhenClearAllSoftRefs, true, \
"Compact when asked to collect CMS gen with clear_all_soft_refs") \
\
......@@ -1504,17 +1508,30 @@ class CommandLineFlags {
"Percentage of MinHeapFreeRatio in CMS generation that is " \
" allocated before a CMS collection cycle commences") \
\
product(intx, CMSBootstrapOccupancy, 50, \
product(intx, CMSTriggerPermRatio, 80, \
"Percentage of MinHeapFreeRatio in the CMS perm generation that" \
" is allocated before a CMS collection cycle commences, that " \
" also collects the perm generation") \
\
product(uintx, CMSBootstrapOccupancy, 50, \
"Percentage CMS generation occupancy at which to " \
" initiate CMS collection for bootstrapping collection stats") \
\
product(intx, CMSInitiatingOccupancyFraction, -1, \
"Percentage CMS generation occupancy to start a CMS collection " \
" cycle (A negative value means that CMSTirggerRatio is used)") \
" cycle (A negative value means that CMSTriggerRatio is used)") \
\
product(intx, CMSInitiatingPermOccupancyFraction, -1, \
"Percentage CMS perm generation occupancy to start a CMScollection"\
" cycle (A negative value means that CMSTriggerPermRatio is used)")\
\
product(bool, UseCMSInitiatingOccupancyOnly, false, \
"Only use occupancy as a crierion for starting a CMS collection") \
\
product(intx, CMSIsTooFullPercentage, 98, \
"An absolute ceiling above which CMS will always consider the" \
" perm gen ripe for collection") \
\
develop(bool, CMSTestInFreeList, false, \
"Check if the coalesced range is already in the " \
"free lists as claimed.") \
......
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