--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/memory/genMarkSweep.cpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,392 @@
+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_genMarkSweep.cpp.incl"
+
+void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
+ bool clear_all_softrefs) {
+ assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
+
+ // hook up weak ref data so it can be used during Mark-Sweep
+ assert(ref_processor() == NULL, "no stomping");
+ _ref_processor = rp;
+ assert(rp != NULL, "should be non-NULL");
+
+ TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
+
+ // When collecting the permanent generation methodOops may be moving,
+ // so we either have to flush all bcp data or convert it into bci.
+ CodeCache::gc_prologue();
+ Threads::gc_prologue();
+
+ // Increment the invocation count for the permanent generation, since it is
+ // implicitly collected whenever we do a full mark sweep collection.
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+ gch->perm_gen()->stat_record()->invocations++;
+
+ // Capture heap size before collection for printing.
+ size_t gch_prev_used = gch->used();
+
+ // Some of the card table updates below assume that the perm gen is
+ // also being collected.
+ assert(level == gch->n_gens() - 1,
+ "All generations are being collected, ergo perm gen too.");
+
+ // Capture used regions for each generation that will be
+ // subject to collection, so that card table adjustments can
+ // be made intelligently (see clear / invalidate further below).
+ gch->save_used_regions(level, true /* perm */);
+
+ allocate_stacks();
+
+ mark_sweep_phase1(level, clear_all_softrefs);
+
+ mark_sweep_phase2();
+
+ // Don't add any more derived pointers during phase3
+ COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
+ COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
+
+ mark_sweep_phase3(level);
+
+ VALIDATE_MARK_SWEEP_ONLY(
+ if (ValidateMarkSweep) {
+ guarantee(_root_refs_stack->length() == 0,
+ "should be empty by now");
+ }
+ )
+
+ mark_sweep_phase4();
+
+ VALIDATE_MARK_SWEEP_ONLY(
+ if (ValidateMarkSweep) {
+ guarantee(_live_oops->length() == _live_oops_moved_to->length(),
+ "should be the same size");
+ }
+ )
+
+ restore_marks();
+
+ // Set saved marks for allocation profiler (and other things? -- dld)
+ // (Should this be in general part?)
+ gch->save_marks();
+
+ deallocate_stacks();
+
+ // If compaction completely evacuated all generations younger than this
+ // one, then we can clear the card table. Otherwise, we must invalidate
+ // it (consider all cards dirty). In the future, we might consider doing
+ // compaction within generations only, and doing card-table sliding.
+ bool all_empty = true;
+ for (int i = 0; all_empty && i < level; i++) {
+ Generation* g = gch->get_gen(i);
+ all_empty = all_empty && gch->get_gen(i)->used() == 0;
+ }
+ GenRemSet* rs = gch->rem_set();
+ // Clear/invalidate below make use of the "prev_used_regions" saved earlier.
+ if (all_empty) {
+ // We've evacuated all generations below us.
+ Generation* g = gch->get_gen(level);
+ rs->clear_into_younger(g, true /* perm */);
+ } else {
+ // Invalidate the cards corresponding to the currently used
+ // region and clear those corresponding to the evacuated region
+ // of all generations just collected (i.e. level and younger).
+ rs->invalidate_or_clear(gch->get_gen(level),
+ true /* younger */,
+ true /* perm */);
+ }
+
+ Threads::gc_epilogue();
+ CodeCache::gc_epilogue();
+
+ if (PrintGC && !PrintGCDetails) {
+ gch->print_heap_change(gch_prev_used);
+ }
+
+ // refs processing: clean slate
+ _ref_processor = NULL;
+
+ // Update heap occupancy information which is used as
+ // input to soft ref clearing policy at the next gc.
+ Universe::update_heap_info_at_gc();
+
+ // Update time of last gc for all generations we collected
+ // (which curently is all the generations in the heap).
+ gch->update_time_of_last_gc(os::javaTimeMillis());
+}
+
+void GenMarkSweep::allocate_stacks() {
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+ // Scratch request on behalf of oldest generation; will do no
+ // allocation.
+ ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);
+
+ // $$$ To cut a corner, we'll only use the first scratch block, and then
+ // revert to malloc.
+ if (scratch != NULL) {
+ _preserved_count_max =
+ scratch->num_words * HeapWordSize / sizeof(PreservedMark);
+ } else {
+ _preserved_count_max = 0;
+ }
+
+ _preserved_marks = (PreservedMark*)scratch;
+ _preserved_count = 0;
+ _preserved_mark_stack = NULL;
+ _preserved_oop_stack = NULL;
+
+ _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
+
+ int size = SystemDictionary::number_of_classes() * 2;
+ _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
+
+#ifdef VALIDATE_MARK_SWEEP
+ if (ValidateMarkSweep) {
+ _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+ _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+ _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+ _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true);
+ _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true);
+ _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+ }
+ if (RecordMarkSweepCompaction) {
+ if (_cur_gc_live_oops == NULL) {
+ _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+ _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+ _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+ _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+ _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+ _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+ } else {
+ _cur_gc_live_oops->clear();
+ _cur_gc_live_oops_moved_to->clear();
+ _cur_gc_live_oops_size->clear();
+ }
+ }
+#endif
+}
+
+
+void GenMarkSweep::deallocate_stacks() {
+ if (_preserved_oop_stack) {
+ delete _preserved_mark_stack;
+ _preserved_mark_stack = NULL;
+ delete _preserved_oop_stack;
+ _preserved_oop_stack = NULL;
+ }
+
+ delete _marking_stack;
+ delete _revisit_klass_stack;
+
+#ifdef VALIDATE_MARK_SWEEP
+ if (ValidateMarkSweep) {
+ delete _root_refs_stack;
+ delete _other_refs_stack;
+ delete _adjusted_pointers;
+ delete _live_oops;
+ delete _live_oops_size;
+ delete _live_oops_moved_to;
+ _live_oops_index = 0;
+ _live_oops_index_at_perm = 0;
+ }
+#endif
+}
+
+void GenMarkSweep::mark_sweep_phase1(int level,
+ bool clear_all_softrefs) {
+ // Recursively traverse all live objects and mark them
+ EventMark m("1 mark object");
+ TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
+ trace(" 1");
+
+ VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+
+ // Because follow_root_closure is created statically, cannot
+ // use OopsInGenClosure constructor which takes a generation,
+ // as the Universe has not been created when the static constructors
+ // are run.
+ follow_root_closure.set_orig_generation(gch->get_gen(level));
+
+ gch->gen_process_strong_roots(level,
+ false, // Younger gens are not roots.
+ true, // Collecting permanent generation.
+ SharedHeap::SO_SystemClasses,
+ &follow_root_closure, &follow_root_closure);
+
+ // Process reference objects found during marking
+ {
+ ReferencePolicy *soft_ref_policy;
+ if (clear_all_softrefs) {
+ soft_ref_policy = new AlwaysClearPolicy();
+ } else {
+#ifdef COMPILER2
+ soft_ref_policy = new LRUMaxHeapPolicy();
+#else
+ soft_ref_policy = new LRUCurrentHeapPolicy();
+#endif // COMPILER2
+ }
+ assert(soft_ref_policy != NULL,"No soft reference policy");
+ ref_processor()->process_discovered_references(
+ soft_ref_policy, &is_alive, &keep_alive,
+ &follow_stack_closure, NULL);
+ }
+
+ // Follow system dictionary roots and unload classes
+ bool purged_class = SystemDictionary::do_unloading(&is_alive);
+
+ // Follow code cache roots
+ CodeCache::do_unloading(&is_alive, &keep_alive, purged_class);
+ follow_stack(); // Flush marking stack
+
+ // Update subklass/sibling/implementor links of live klasses
+ follow_weak_klass_links();
+ assert(_marking_stack->is_empty(), "just drained");
+
+ // Visit symbol and interned string tables and delete unmarked oops
+ SymbolTable::unlink(&is_alive);
+ StringTable::unlink(&is_alive);
+
+ assert(_marking_stack->is_empty(), "stack should be empty by now");
+}
+
+
+void GenMarkSweep::mark_sweep_phase2() {
+ // Now all live objects are marked, compute the new object addresses.
+
+ // It is imperative that we traverse perm_gen LAST. If dead space is
+ // allowed a range of dead object may get overwritten by a dead int
+ // array. If perm_gen is not traversed last a klassOop may get
+ // overwritten. This is fine since it is dead, but if the class has dead
+ // instances we have to skip them, and in order to find their size we
+ // need the klassOop!
+ //
+ // It is not required that we traverse spaces in the same order in
+ // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
+ // tracking expects us to do so. See comment under phase4.
+
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+ Generation* pg = gch->perm_gen();
+
+ EventMark m("2 compute new addresses");
+ TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
+ trace("2");
+
+ VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+ gch->prepare_for_compaction();
+
+ VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index);
+ CompactPoint perm_cp(pg, NULL, NULL);
+ pg->prepare_for_compaction(&perm_cp);
+}
+
+class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
+public:
+ void do_generation(Generation* gen) {
+ gen->adjust_pointers();
+ }
+};
+
+void GenMarkSweep::mark_sweep_phase3(int level) {
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+ Generation* pg = gch->perm_gen();
+
+ // Adjust the pointers to reflect the new locations
+ EventMark m("3 adjust pointers");
+ TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
+ trace("3");
+
+ VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+ // Needs to be done before the system dictionary is adjusted.
+ pg->pre_adjust_pointers();
+
+ // Because the two closures below are created statically, cannot
+ // use OopsInGenClosure constructor which takes a generation,
+ // as the Universe has not been created when the static constructors
+ // are run.
+ adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level));
+ adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
+
+ gch->gen_process_strong_roots(level,
+ false, // Younger gens are not roots.
+ true, // Collecting permanent generation.
+ SharedHeap::SO_AllClasses,
+ &adjust_root_pointer_closure,
+ &adjust_root_pointer_closure);
+
+ // Now adjust pointers in remaining weak roots. (All of which should
+ // have been cleared if they pointed to non-surviving objects.)
+ gch->gen_process_weak_roots(&adjust_root_pointer_closure,
+ &adjust_pointer_closure);
+
+ adjust_marks();
+ GenAdjustPointersClosure blk;
+ gch->generation_iterate(&blk, true);
+ pg->adjust_pointers();
+}
+
+class GenCompactClosure: public GenCollectedHeap::GenClosure {
+public:
+ void do_generation(Generation* gen) {
+ gen->compact();
+ }
+};
+
+void GenMarkSweep::mark_sweep_phase4() {
+ // All pointers are now adjusted, move objects accordingly
+
+ // It is imperative that we traverse perm_gen first in phase4. All
+ // classes must be allocated earlier than their instances, and traversing
+ // perm_gen first makes sure that all klassOops have moved to their new
+ // location before any instance does a dispatch through it's klass!
+
+ // The ValidateMarkSweep live oops tracking expects us to traverse spaces
+ // in the same order in phase2, phase3 and phase4. We don't quite do that
+ // here (perm_gen first rather than last), so we tell the validate code
+ // to use a higher index (saved from phase2) when verifying perm_gen.
+ GenCollectedHeap* gch = GenCollectedHeap::heap();
+ Generation* pg = gch->perm_gen();
+
+ EventMark m("4 compact heap");
+ TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
+ trace("4");
+
+ VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true));
+
+ pg->compact();
+
+ VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+ GenCompactClosure blk;
+ gch->generation_iterate(&blk, true);
+
+ VALIDATE_MARK_SWEEP_ONLY(compaction_complete());
+
+ pg->post_compact(); // Shared spaces verification.
+}