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8048248: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
This commit is contained in:
Stefan Karlsson
parent
b0138be158
commit
8c3aced316
75 changed files with 2169 additions and 874 deletions
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@ -24,6 +24,7 @@
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#include "precompiled.hpp"
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#include "classfile/symbolTable.hpp"
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#include "code/codeCache.hpp"
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#include "gc_implementation/g1/concurrentMark.inline.hpp"
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#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
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#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
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@ -39,6 +40,7 @@
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#include "gc_implementation/shared/gcTimer.hpp"
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#include "gc_implementation/shared/gcTrace.hpp"
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#include "gc_implementation/shared/gcTraceTime.hpp"
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#include "memory/allocation.hpp"
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#include "memory/genOopClosures.inline.hpp"
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#include "memory/referencePolicy.hpp"
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#include "memory/resourceArea.hpp"
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@ -58,8 +60,8 @@ CMBitMapRO::CMBitMapRO(int shifter) :
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_bmWordSize = 0;
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}
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HeapWord* CMBitMapRO::getNextMarkedWordAddress(HeapWord* addr,
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HeapWord* limit) const {
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HeapWord* CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
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const HeapWord* limit) const {
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// First we must round addr *up* to a possible object boundary.
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addr = (HeapWord*)align_size_up((intptr_t)addr,
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HeapWordSize << _shifter);
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@ -76,8 +78,8 @@ HeapWord* CMBitMapRO::getNextMarkedWordAddress(HeapWord* addr,
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return nextAddr;
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}
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HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(HeapWord* addr,
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HeapWord* limit) const {
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HeapWord* CMBitMapRO::getNextUnmarkedWordAddress(const HeapWord* addr,
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const HeapWord* limit) const {
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size_t addrOffset = heapWordToOffset(addr);
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if (limit == NULL) {
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limit = _bmStartWord + _bmWordSize;
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@ -1223,6 +1225,9 @@ public:
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};
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void ConcurrentMark::scanRootRegions() {
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// Start of concurrent marking.
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ClassLoaderDataGraph::clear_claimed_marks();
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// scan_in_progress() will have been set to true only if there was
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// at least one root region to scan. So, if it's false, we
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// should not attempt to do any further work.
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@ -1271,7 +1276,7 @@ void ConcurrentMark::markFromRoots() {
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CMConcurrentMarkingTask markingTask(this, cmThread());
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if (use_parallel_marking_threads()) {
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_parallel_workers->set_active_workers((int)active_workers);
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// Don't set _n_par_threads because it affects MT in process_strong_roots()
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// Don't set _n_par_threads because it affects MT in process_roots()
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// and the decisions on that MT processing is made elsewhere.
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assert(_parallel_workers->active_workers() > 0, "Should have been set");
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_parallel_workers->run_task(&markingTask);
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@ -2142,23 +2147,29 @@ void ConcurrentMark::cleanup() {
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// Update the soft reference policy with the new heap occupancy.
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Universe::update_heap_info_at_gc();
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// We need to make this be a "collection" so any collection pause that
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// races with it goes around and waits for completeCleanup to finish.
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g1h->increment_total_collections();
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// We reclaimed old regions so we should calculate the sizes to make
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// sure we update the old gen/space data.
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g1h->g1mm()->update_sizes();
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if (VerifyDuringGC) {
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HandleMark hm; // handle scope
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Universe::heap()->prepare_for_verify();
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Universe::verify(VerifyOption_G1UsePrevMarking,
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" VerifyDuringGC:(after)");
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}
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g1h->check_bitmaps("Cleanup End");
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g1h->verify_region_sets_optional();
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// We need to make this be a "collection" so any collection pause that
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// races with it goes around and waits for completeCleanup to finish.
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g1h->increment_total_collections();
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// Clean out dead classes and update Metaspace sizes.
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ClassLoaderDataGraph::purge();
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MetaspaceGC::compute_new_size();
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// We reclaimed old regions so we should calculate the sizes to make
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// sure we update the old gen/space data.
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g1h->g1mm()->update_sizes();
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g1h->trace_heap_after_concurrent_cycle();
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}
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@ -2445,6 +2456,26 @@ void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
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_g1h->set_par_threads(0);
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}
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void ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
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G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
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}
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// Helper class to get rid of some boilerplate code.
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class G1RemarkGCTraceTime : public GCTraceTime {
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static bool doit_and_prepend(bool doit) {
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if (doit) {
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gclog_or_tty->put(' ');
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}
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return doit;
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}
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public:
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G1RemarkGCTraceTime(const char* title, bool doit)
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: GCTraceTime(title, doit_and_prepend(doit), false, G1CollectedHeap::heap()->gc_timer_cm(),
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G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()) {
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}
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};
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void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
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if (has_overflown()) {
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// Skip processing the discovered references if we have
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@ -2557,9 +2588,28 @@ void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
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return;
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}
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g1h->unlink_string_and_symbol_table(&g1_is_alive,
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/* process_strings */ false, // currently strings are always roots
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/* process_symbols */ true);
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assert(_markStack.isEmpty(), "Marking should have completed");
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// Unload Klasses, String, Symbols, Code Cache, etc.
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G1RemarkGCTraceTime trace("Unloading", G1Log::finer());
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bool purged_classes;
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{
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G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest());
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purged_classes = SystemDictionary::do_unloading(&g1_is_alive);
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}
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{
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G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest());
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weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
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}
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if (G1StringDedup::is_enabled()) {
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G1RemarkGCTraceTime trace("String Deduplication Unlink", G1Log::finest());
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G1StringDedup::unlink(&g1_is_alive);
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}
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}
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void ConcurrentMark::swapMarkBitMaps() {
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@ -2568,6 +2618,57 @@ void ConcurrentMark::swapMarkBitMaps() {
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_nextMarkBitMap = (CMBitMap*) temp;
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}
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class CMObjectClosure;
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// Closure for iterating over objects, currently only used for
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// processing SATB buffers.
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class CMObjectClosure : public ObjectClosure {
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private:
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CMTask* _task;
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public:
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void do_object(oop obj) {
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_task->deal_with_reference(obj);
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}
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CMObjectClosure(CMTask* task) : _task(task) { }
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};
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class G1RemarkThreadsClosure : public ThreadClosure {
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CMObjectClosure _cm_obj;
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G1CMOopClosure _cm_cl;
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MarkingCodeBlobClosure _code_cl;
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int _thread_parity;
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bool _is_par;
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public:
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G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task, bool is_par) :
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_cm_obj(task), _cm_cl(g1h, g1h->concurrent_mark(), task), _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
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_thread_parity(SharedHeap::heap()->strong_roots_parity()), _is_par(is_par) {}
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void do_thread(Thread* thread) {
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if (thread->is_Java_thread()) {
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if (thread->claim_oops_do(_is_par, _thread_parity)) {
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JavaThread* jt = (JavaThread*)thread;
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// In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
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// however the liveness of oops reachable from nmethods have very complex lifecycles:
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// * Alive if on the stack of an executing method
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// * Weakly reachable otherwise
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// Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
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// live by the SATB invariant but other oops recorded in nmethods may behave differently.
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jt->nmethods_do(&_code_cl);
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jt->satb_mark_queue().apply_closure_and_empty(&_cm_obj);
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}
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} else if (thread->is_VM_thread()) {
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if (thread->claim_oops_do(_is_par, _thread_parity)) {
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JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_obj);
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}
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}
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}
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};
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class CMRemarkTask: public AbstractGangTask {
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private:
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ConcurrentMark* _cm;
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@ -2579,6 +2680,14 @@ public:
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if (worker_id < _cm->active_tasks()) {
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CMTask* task = _cm->task(worker_id);
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task->record_start_time();
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{
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ResourceMark rm;
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HandleMark hm;
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G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task, !_is_serial);
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Threads::threads_do(&threads_f);
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}
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do {
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task->do_marking_step(1000000000.0 /* something very large */,
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true /* do_termination */,
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@ -2601,6 +2710,8 @@ void ConcurrentMark::checkpointRootsFinalWork() {
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HandleMark hm;
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G1CollectedHeap* g1h = G1CollectedHeap::heap();
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G1RemarkGCTraceTime trace("Finalize Marking", G1Log::finer());
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g1h->ensure_parsability(false);
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if (G1CollectedHeap::use_parallel_gc_threads()) {
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@ -3430,20 +3541,6 @@ public:
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}
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};
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// Closure for iterating over objects, currently only used for
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// processing SATB buffers.
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class CMObjectClosure : public ObjectClosure {
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private:
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CMTask* _task;
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public:
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void do_object(oop obj) {
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_task->deal_with_reference(obj);
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}
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CMObjectClosure(CMTask* task) : _task(task) { }
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};
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G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
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ConcurrentMark* cm,
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CMTask* task)
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@ -3908,15 +4005,6 @@ void CMTask::drain_satb_buffers() {
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}
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}
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if (!concurrent() && !has_aborted()) {
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// We should only do this during remark.
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if (G1CollectedHeap::use_parallel_gc_threads()) {
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satb_mq_set.par_iterate_closure_all_threads(_worker_id);
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} else {
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satb_mq_set.iterate_closure_all_threads();
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}
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}
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_draining_satb_buffers = false;
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assert(has_aborted() ||
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