jdk-sandbox: comparison hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

equal deleted inserted replaced

-:70fb742e40aa
+:d27050bdfb04
 #include "gc_implementation/shared/gcHeapSummary.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
 #include "gc_implementation/shared/isGCActiveMark.hpp"
+#include "memory/allocation.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "memory/generationSpec.hpp"
 #include "memory/iterator.hpp"
 #include "memory/referenceProcessor.hpp"
 #include "oops/oop.inline.hpp"
 // Notes on implementation of parallelism in different tasks.
 //
 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
 // The number of GC workers is passed to heap_region_par_iterate_chunked().
 // It does use run_task() which sets _n_workers in the task.
-// G1ParTask executes g1_process_strong_roots() ->
+// G1ParTask executes g1_process_roots() ->
-// SharedHeap::process_strong_roots() which calls eventually to
+// SharedHeap::process_roots() which calls eventually to
 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
-// SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
+// SequentialSubTasksDone.  SharedHeap::process_roots() also
 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
 //
 // Local to this file.
 "Expected to be executed serially by the VM thread at this point");
 if (!silent) { gclog_or_tty->print("Roots "); }
 VerifyRootsClosure rootsCl(vo);
 VerifyKlassClosure klassCl(this, &rootsCl);
+CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
 // We apply the relevant closures to all the oops in the
-// system dictionary, class loader data graph and the string table.
+// system dictionary, class loader data graph, the string table
-// Don't verify the code cache here, since it's verified below.
+// and the nmethods in the code cache.
-const int so = SO_AllClasses | SO_Strings;
-// Need cleared claim bits for the strong roots processing
-ClassLoaderDataGraph::clear_claimed_marks();
-process_strong_roots(true,      // activate StrongRootsScope
-ScanningOption(so),  // roots scanning options
-&rootsCl,
-&klassCl
-);
-// Verify the nmethods in the code cache.
 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
-CodeCache::blobs_do(&blobsCl);
+process_all_roots(true,            // activate StrongRootsScope
+SO_AllCodeCache, // roots scanning options
+&rootsCl,
+&cldCl,
+&blobsCl);
 bool failures = rootsCl.failures() || codeRootsCl.failures();
 if (vo != VerifyOption_G1UseMarkWord) {
 // If we're verifying during a full GC then the region sets
 gc_prologue(false);
 increment_total_collections(false /* full gc */);
 increment_gc_time_stamp();
 verify_before_gc();
 check_bitmaps("GC Start");
 COMPILER2_PRESENT(DerivedPointerTable::clear());
 // Please see comment in g1CollectedHeap.hpp and
 void G1CollectedHeap::release_mutator_alloc_region() {
 _mutator_alloc_region.release();
 assert(_mutator_alloc_region.get() == NULL, "post-condition");
 }
-void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
+void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
-assert_at_safepoint(true /* should_be_vm_thread */);
-_survivor_gc_alloc_region.init();
-_old_gc_alloc_region.init();
 HeapRegion* retained_region = _retained_old_gc_alloc_region;
 _retained_old_gc_alloc_region = NULL;
 // We will discard the current GC alloc region if:
 // a) it's in the collection set (it can happen!),
 _hr_printer.reuse(retained_region);
 evacuation_info.set_alloc_regions_used_before(retained_region->used());
 }
 }
+void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
+assert_at_safepoint(true /* should_be_vm_thread */);
+_survivor_gc_alloc_region.init();
+_old_gc_alloc_region.init();
+use_retained_old_gc_alloc_region(evacuation_info);
+}
 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
 _old_gc_alloc_region.count());
 _survivor_gc_alloc_region.release();
 // If we have an old GC alloc region to release, we'll save it in
 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
 _scanned_klass->record_modified_oops();
 }
 }
-template <G1Barrier barrier, bool do_mark_object>
+template <G1Barrier barrier, G1Mark do_mark_object>
 template <class T>
 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
 T heap_oop = oopDesc::load_heap_oop(p);
 if (oopDesc::is_null(heap_oop)) {
 } else {
 forwardee = _par_scan_state->copy_to_survivor_space(obj);
 }
 assert(forwardee != NULL, "forwardee should not be NULL");
 oopDesc::encode_store_heap_oop(p, forwardee);
-if (do_mark_object && forwardee != obj) {
+if (do_mark_object != G1MarkNone && forwardee != obj) {
 // If the object is self-forwarded we don't need to explicitly
 // mark it, the evacuation failure protocol will do so.
 mark_forwarded_object(obj, forwardee);
 }
 if (barrier == G1BarrierKlass) {
 do_klass_barrier(p, forwardee);
 }
 } else {
 // The object is not in collection set. If we're a root scanning
-// closure during an initial mark pause (i.e. do_mark_object will
+// closure during an initial mark pause then attempt to mark the object.
-// be true) then attempt to mark the object.
+if (do_mark_object == G1MarkFromRoot) {
-if (do_mark_object) {
 mark_object(obj);
 }
 }
 if (barrier == G1BarrierEvac) {
 _par_scan_state->update_rs(_from, p, _worker_id);
 }
 }
-template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
+template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
-template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
+template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
 class G1ParEvacuateFollowersClosure : public VoidClosure {
 protected:
 G1CollectedHeap*              _g1h;
 G1ParScanThreadState*         _par_scan_state;
 _g1h->set_n_termination(active_workers);
 terminator()->reset_for_reuse(active_workers);
 _n_workers = active_workers;
 }
+// Helps out with CLD processing.
+//
+// During InitialMark we need to:
+// 1) Scavenge all CLDs for the young GC.
+// 2) Mark all objects directly reachable from strong CLDs.
+template <G1Mark do_mark_object>
+class G1CLDClosure : public CLDClosure {
+G1ParCopyClosure<G1BarrierNone,  do_mark_object>* _oop_closure;
+G1ParCopyClosure<G1BarrierKlass, do_mark_object>  _oop_in_klass_closure;
+G1KlassScanClosure                                _klass_in_cld_closure;
+bool                                              _claim;
+public:
+G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
+bool only_young, bool claim)
+: _oop_closure(oop_closure),
+_oop_in_klass_closure(oop_closure->g1(),
+oop_closure->pss(),
+oop_closure->rp()),
+_klass_in_cld_closure(&_oop_in_klass_closure, only_young),
+_claim(claim) {
+}
+void do_cld(ClassLoaderData* cld) {
+cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
+}
+};
+class G1CodeBlobClosure: public CodeBlobClosure {
+OopClosure* _f;
+public:
+G1CodeBlobClosure(OopClosure* f) : _f(f) {}
+void do_code_blob(CodeBlob* blob) {
+nmethod* that = blob->as_nmethod_or_null();
+if (that != NULL) {
+if (!that->test_set_oops_do_mark()) {
+that->oops_do(_f);
+that->fix_oop_relocations();
+}
+}
+}
+};
 void work(uint worker_id) {
 if (worker_id >= _n_workers) return;  // no work needed this round
 double start_time_ms = os::elapsedTime() * 1000.0;
 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
 G1ParScanThreadState            pss(_g1h, worker_id, rp);
 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
 pss.set_evac_failure_closure(&evac_failure_cl);
-G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
+bool only_young = _g1h->g1_policy()->gcs_are_young();
-G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
+// Non-IM young GC.
-G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
+G1ParCopyClosure<G1BarrierNone, G1MarkNone>             scan_only_root_cl(_g1h, &pss, rp);
-G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
+G1CLDClosure<G1MarkNone>                                scan_only_cld_cl(&scan_only_root_cl,
+only_young, // Only process dirty klasses.
-bool only_young                 = _g1h->g1_policy()->gcs_are_young();
+false);     // No need to claim CLDs.
-G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
+// IM young GC.
-G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
+//    Strong roots closures.
+G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot>         scan_mark_root_cl(_g1h, &pss, rp);
-OopClosure*                    scan_root_cl = &only_scan_root_cl;
+G1CLDClosure<G1MarkFromRoot>                            scan_mark_cld_cl(&scan_mark_root_cl,
-G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
+false, // Process all klasses.
+true); // Need to claim CLDs.
+//    Weak roots closures.
+G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
+G1CLDClosure<G1MarkPromotedFromRoot>                    scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
+false, // Process all klasses.
+true); // Need to claim CLDs.
+G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
+G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
+// IM Weak code roots are handled later.
+OopClosure* strong_root_cl;
+OopClosure* weak_root_cl;
+CLDClosure* strong_cld_cl;
+CLDClosure* weak_cld_cl;
+CodeBlobClosure* strong_code_cl;
 if (_g1h->g1_policy()->during_initial_mark_pause()) {
 // We also need to mark copied objects.
-scan_root_cl = &scan_mark_root_cl;
+strong_root_cl = &scan_mark_root_cl;
-scan_klasses_cl = &scan_mark_klasses_cl_s;
+weak_root_cl   = &scan_mark_weak_root_cl;
+strong_cld_cl  = &scan_mark_cld_cl;
+weak_cld_cl    = &scan_mark_weak_cld_cl;
+strong_code_cl = &scan_mark_code_cl;
+} else {
+strong_root_cl = &scan_only_root_cl;
+weak_root_cl   = &scan_only_root_cl;
+strong_cld_cl  = &scan_only_cld_cl;
+weak_cld_cl    = &scan_only_cld_cl;
+strong_code_cl = &scan_only_code_cl;
 }
-G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
+G1ParPushHeapRSClosure  push_heap_rs_cl(_g1h, &pss);
-// Don't scan the scavengable methods in the code cache as part
-// of strong root scanning. The code roots that point into a
-// region in the collection set are scanned when we scan the
-// region's RSet.
-int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
 pss.start_strong_roots();
-_g1h->g1_process_strong_roots(/* is scavenging */ true,
+_g1h->g1_process_roots(strong_root_cl,
-SharedHeap::ScanningOption(so),
+weak_root_cl,
-scan_root_cl,
+&push_heap_rs_cl,
-&push_heap_rs_cl,
+strong_cld_cl,
-scan_klasses_cl,
+weak_cld_cl,
-worker_id);
+strong_code_cl,
+worker_id);
 pss.end_strong_roots();
 {
 double start = os::elapsedTime();
 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
 // This method is run in a GC worker.
 void
 G1CollectedHeap::
-g1_process_strong_roots(bool is_scavenging,
+g1_process_roots(OopClosure* scan_non_heap_roots,
-ScanningOption so,
+OopClosure* scan_non_heap_weak_roots,
-OopClosure* scan_non_heap_roots,
+OopsInHeapRegionClosure* scan_rs,
-OopsInHeapRegionClosure* scan_rs,
+CLDClosure* scan_strong_clds,
-G1KlassScanClosure* scan_klasses,
+CLDClosure* scan_weak_clds,
-uint worker_i) {
+CodeBlobClosure* scan_strong_code,
+uint worker_i) {
-// First scan the strong roots
+// First scan the shared roots.
 double ext_roots_start = os::elapsedTime();
 double closure_app_time_sec = 0.0;
+bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
+BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
-process_strong_roots(false, // no scoping; this is parallel code
-so,
+process_roots(false, // no scoping; this is parallel code
-&buf_scan_non_heap_roots,
+SharedHeap::SO_None,
-scan_klasses
+&buf_scan_non_heap_roots,
-);
+&buf_scan_non_heap_weak_roots,
+scan_strong_clds,
+// Initial Mark handles the weak CLDs separately.
+(during_im ? NULL : scan_weak_clds),
+scan_strong_code);
 // Now the CM ref_processor roots.
 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
 // We need to treat the discovered reference lists of the
 // concurrent mark ref processor as roots and keep entries
 // (which are added by the marking threads) on them live
 // until they can be processed at the end of marking.
 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
 }
+if (during_im) {
+// Barrier to make sure all workers passed
+// the strong CLD and strong nmethods phases.
+active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
+// Now take the complement of the strong CLDs.
+ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
+}
 // Finish up any enqueued closure apps (attributed as object copy time).
 buf_scan_non_heap_roots.done();
+buf_scan_non_heap_weak_roots.done();
-double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
+double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
++ buf_scan_non_heap_weak_roots.closure_app_seconds();
 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
 double ext_root_time_ms =
 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
 }
 }
 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
-// If this is an initial mark pause, and we're not scanning
-// the entire code cache, we need to mark the oops in the
-// strong code root lists for the regions that are not in
-// the collection set.
-// Note all threads participate in this set of root tasks.
-double mark_strong_code_roots_ms = 0.0;
-if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
-double mark_strong_roots_start = os::elapsedTime();
-mark_strong_code_roots(worker_i);
-mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
-}
-g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
 // Now scan the complement of the collection set.
-CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
+MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
-g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
+g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
 _process_strong_tasks->all_tasks_completed();
 }
 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
 int _symbols_removed;
 bool _do_in_parallel;
 public:
 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
-AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
+AbstractGangTask("String/Symbol Unlinking"),
+_is_alive(is_alive),
 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
 _initial_string_table_size = StringTable::the_table()->table_size();
 err_msg("claim value %d after unlink less than initial string table size %d",
 StringTable::parallel_claimed_index(), _initial_string_table_size));
 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
 err_msg("claim value %d after unlink less than initial symbol table size %d",
 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
+if (G1TraceStringSymbolTableScrubbing) {
+gclog_or_tty->print_cr("Cleaned string and symbol table, "
+"strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
+"symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
+strings_processed(), strings_removed(),
+symbols_processed(), symbols_removed());
+}
 }
 void work(uint worker_id) {
 if (_do_in_parallel) {
 int strings_processed = 0;
 size_t symbols_processed() const { return (size_t)_symbols_processed; }
 size_t symbols_removed()   const { return (size_t)_symbols_removed; }
 };
-void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
+class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
-bool process_strings, bool process_symbols) {
+private:
+static Monitor* _lock;
+BoolObjectClosure* const _is_alive;
+const bool               _unloading_occurred;
+const uint               _num_workers;
+// Variables used to claim nmethods.
+nmethod* _first_nmethod;
+volatile nmethod* _claimed_nmethod;
+// The list of nmethods that need to be processed by the second pass.
+volatile nmethod* _postponed_list;
+volatile uint     _num_entered_barrier;
+public:
+G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
+_is_alive(is_alive),
+_unloading_occurred(unloading_occurred),
+_num_workers(num_workers),
+_first_nmethod(NULL),
+_claimed_nmethod(NULL),
+_postponed_list(NULL),
+_num_entered_barrier(0)
+{
+nmethod::increase_unloading_clock();
+_first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
+_claimed_nmethod = (volatile nmethod*)_first_nmethod;
+}
+~G1CodeCacheUnloadingTask() {
+CodeCache::verify_clean_inline_caches();
+CodeCache::set_needs_cache_clean(false);
+guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
+CodeCache::verify_icholder_relocations();
+}
+private:
+void add_to_postponed_list(nmethod* nm) {
+nmethod* old;
+do {
+old = (nmethod*)_postponed_list;
+nm->set_unloading_next(old);
+} while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
+}
+void clean_nmethod(nmethod* nm) {
+bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
+if (postponed) {
+// This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
+add_to_postponed_list(nm);
+}
+// Mark that this thread has been cleaned/unloaded.
+// After this call, it will be safe to ask if this nmethod was unloaded or not.
+nm->set_unloading_clock(nmethod::global_unloading_clock());
+}
+void clean_nmethod_postponed(nmethod* nm) {
+nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
+}
+static const int MaxClaimNmethods = 16;
+void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
+nmethod* first;
+nmethod* last;
+do {
+*num_claimed_nmethods = 0;
+first = last = (nmethod*)_claimed_nmethod;
+if (first != NULL) {
+for (int i = 0; i < MaxClaimNmethods; i++) {
+last = CodeCache::alive_nmethod(CodeCache::next(last));
+if (last == NULL) {
+break;
+}
+claimed_nmethods[i] = last;
+(*num_claimed_nmethods)++;
+}
+}
+} while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
+}
+nmethod* claim_postponed_nmethod() {
+nmethod* claim;
+nmethod* next;
+do {
+claim = (nmethod*)_postponed_list;
+if (claim == NULL) {
+return NULL;
+}
+next = claim->unloading_next();
+} while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
+return claim;
+}
+public:
+// Mark that we're done with the first pass of nmethod cleaning.
+void barrier_mark(uint worker_id) {
+MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+_num_entered_barrier++;
+if (_num_entered_barrier == _num_workers) {
+ml.notify_all();
+}
+}
+// See if we have to wait for the other workers to
+// finish their first-pass nmethod cleaning work.
+void barrier_wait(uint worker_id) {
+if (_num_entered_barrier < _num_workers) {
+MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
+while (_num_entered_barrier < _num_workers) {
+ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
+}
+}
+}
+// Cleaning and unloading of nmethods. Some work has to be postponed
+// to the second pass, when we know which nmethods survive.
+void work_first_pass(uint worker_id) {
+// The first nmethods is claimed by the first worker.
+if (worker_id == 0 && _first_nmethod != NULL) {
+clean_nmethod(_first_nmethod);
+_first_nmethod = NULL;
+}
+int num_claimed_nmethods;
+nmethod* claimed_nmethods[MaxClaimNmethods];
+while (true) {
+claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
+if (num_claimed_nmethods == 0) {
+break;
+}
+for (int i = 0; i < num_claimed_nmethods; i++) {
+clean_nmethod(claimed_nmethods[i]);
+}
+}
+}
+void work_second_pass(uint worker_id) {
+nmethod* nm;
+// Take care of postponed nmethods.
+while ((nm = claim_postponed_nmethod()) != NULL) {
+clean_nmethod_postponed(nm);
+}
+}
+};
+Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
+class G1KlassCleaningTask : public StackObj {
+BoolObjectClosure*                      _is_alive;
+volatile jint                           _clean_klass_tree_claimed;
+ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
+public:
+G1KlassCleaningTask(BoolObjectClosure* is_alive) :
+_is_alive(is_alive),
+_clean_klass_tree_claimed(0),
+_klass_iterator() {
+}
+private:
+bool claim_clean_klass_tree_task() {
+if (_clean_klass_tree_claimed) {
+return false;
+}
+return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
+}
+InstanceKlass* claim_next_klass() {
+Klass* klass;
+do {
+klass =_klass_iterator.next_klass();
+} while (klass != NULL && !klass->oop_is_instance());
+return (InstanceKlass*)klass;
+}
+public:
+void clean_klass(InstanceKlass* ik) {
+ik->clean_implementors_list(_is_alive);
+ik->clean_method_data(_is_alive);
+// G1 specific cleanup work that has
+// been moved here to be done in parallel.
+ik->clean_dependent_nmethods();
+}
+void work() {
+ResourceMark rm;
+// One worker will clean the subklass/sibling klass tree.
+if (claim_clean_klass_tree_task()) {
+Klass::clean_subklass_tree(_is_alive);
+}
+// All workers will help cleaning the classes,
+InstanceKlass* klass;
+while ((klass = claim_next_klass()) != NULL) {
+clean_klass(klass);
+}
+}
+};
+// To minimize the remark pause times, the tasks below are done in parallel.
+class G1ParallelCleaningTask : public AbstractGangTask {
+private:
+G1StringSymbolTableUnlinkTask _string_symbol_task;
+G1CodeCacheUnloadingTask      _code_cache_task;
+G1KlassCleaningTask           _klass_cleaning_task;
+public:
+// The constructor is run in the VMThread.
+G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
+AbstractGangTask("Parallel Cleaning"),
+_string_symbol_task(is_alive, process_strings, process_symbols),
+_code_cache_task(num_workers, is_alive, unloading_occurred),
+_klass_cleaning_task(is_alive) {
+}
+// The parallel work done by all worker threads.
+void work(uint worker_id) {
+// Do first pass of code cache cleaning.
+_code_cache_task.work_first_pass(worker_id);
+// Let the threads, mark that the first pass is done.
+_code_cache_task.barrier_mark(worker_id);
+// Clean the Strings and Symbols.
+_string_symbol_task.work(worker_id);
+// Wait for all workers to finish the first code cache cleaning pass.
+_code_cache_task.barrier_wait(worker_id);
+// Do the second code cache cleaning work, which realize on
+// the liveness information gathered during the first pass.
+_code_cache_task.work_second_pass(worker_id);
+// Clean all klasses that were not unloaded.
+_klass_cleaning_task.work();
+}
+};
+void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
+bool process_strings,
+bool process_symbols,
+bool class_unloading_occurred) {
 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
-_g1h->workers()->active_workers() : 1);
+workers()->active_workers() : 1);
-G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
+G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
+n_workers, class_unloading_occurred);
 if (G1CollectedHeap::use_parallel_gc_threads()) {
 set_par_threads(n_workers);
 workers()->run_task(&g1_unlink_task);
 set_par_threads(0);
 } else {
 g1_unlink_task.work(0);
 }
-if (G1TraceStringSymbolTableScrubbing) {
+}
-gclog_or_tty->print_cr("Cleaned string and symbol table, "
-"strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
+void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
-"symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
+bool process_strings, bool process_symbols) {
-g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
+{
-g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
+uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
+_g1h->workers()->active_workers() : 1);
+G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
+if (G1CollectedHeap::use_parallel_gc_threads()) {
+set_par_threads(n_workers);
+workers()->run_task(&g1_unlink_task);
+set_par_threads(0);
+} else {
+g1_unlink_task.work(0);
+}
 }
 if (G1StringDedup::is_enabled()) {
 G1StringDedup::unlink(is_alive);
 }
 double start_par_time_sec = os::elapsedTime();
 double end_par_time_sec;
 {
 StrongRootsScope srs(this);
+// InitialMark needs claim bits to keep track of the marked-through CLDs.
+if (g1_policy()->during_initial_mark_pause()) {
+ClassLoaderDataGraph::clear_claimed_marks();
+}
 if (G1CollectedHeap::use_parallel_gc_threads()) {
 // The individual threads will set their evac-failure closures.
 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
 // These tasks use ShareHeap::_process_strong_tasks
 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
 }
-// Mark all the code roots that point into regions *not* in the
-// collection set.
-//
-// Note we do not want to use a "marking" CodeBlobToOopClosure while
-// walking the the code roots lists of regions not in the collection
-// set. Suppose we have an nmethod (M) that points to objects in two
-// separate regions - one in the collection set (R1) and one not (R2).
-// Using a "marking" CodeBlobToOopClosure here would result in "marking"
-// nmethod M when walking the code roots for R1. When we come to scan
-// the code roots for R2, we would see that M is already marked and it
-// would be skipped and the objects in R2 that are referenced from M
-// would not be evacuated.
-class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
-class MarkStrongCodeRootOopClosure: public OopClosure {
-ConcurrentMark* _cm;
-HeapRegion* _hr;
-uint _worker_id;
-template <class T> void do_oop_work(T* p) {
-T heap_oop = oopDesc::load_heap_oop(p);
-if (!oopDesc::is_null(heap_oop)) {
-oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
-// Only mark objects in the region (which is assumed
-// to be not in the collection set).
-if (_hr->is_in(obj)) {
-_cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
-}
-}
-}
-public:
-MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
-_cm(cm), _hr(hr), _worker_id(worker_id) {
-assert(!_hr->in_collection_set(), "sanity");
-}
-void do_oop(narrowOop* p) { do_oop_work(p); }
-void do_oop(oop* p)       { do_oop_work(p); }
-};
-MarkStrongCodeRootOopClosure _oop_cl;
-public:
-MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
-_oop_cl(cm, hr, worker_id) {}
-void do_code_blob(CodeBlob* cb) {
-nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
-if (nm != NULL) {
-nm->oops_do(&_oop_cl);
-}
-}
-};
-class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
-G1CollectedHeap* _g1h;
-uint _worker_id;
-public:
-MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
-_g1h(g1h), _worker_id(worker_id) {}
-bool doHeapRegion(HeapRegion *hr) {
-HeapRegionRemSet* hrrs = hr->rem_set();
-if (hr->continuesHumongous()) {
-// Code roots should never be attached to a continuation of a humongous region
-assert(hrrs->strong_code_roots_list_length() == 0,
-err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
-" starting at "HR_FORMAT", but has "SIZE_FORMAT,
-HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
-hrrs->strong_code_roots_list_length()));
-return false;
-}
-if (hr->in_collection_set()) {
-// Don't mark code roots into regions in the collection set here.
-// They will be marked when we scan them.
-return false;
-}
-MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
-hr->strong_code_roots_do(&cb_cl);
-return false;
-}
-};
-void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
-MarkStrongCodeRootsHRClosure cl(this, worker_id);
-if (G1CollectedHeap::use_parallel_gc_threads()) {
-heap_region_par_iterate_chunked(&cl,
-worker_id,
-workers()->active_workers(),
-HeapRegion::ParMarkRootClaimValue);
-} else {
-heap_region_iterate(&cl);
-}
-}
 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
 G1CollectedHeap* _g1h;
 public:
 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :

changeset 25492	d27050bdfb04
parent 25491	70fb742e40aa
child 25500	4d2e06147d1e