1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp Thu Jun 05 15:57:56 2008 -0700
1.3 @@ -0,0 +1,381 @@
1.4 +/*
1.5 + * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "incls/_precompiled.incl"
1.29 +#include "incls/_g1MarkSweep.cpp.incl"
1.30 +
1.31 +class HeapRegion;
1.32 +
1.33 +void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
1.34 + bool clear_all_softrefs) {
1.35 + assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1.36 +
1.37 + // hook up weak ref data so it can be used during Mark-Sweep
1.38 + assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
1.39 + GenMarkSweep::_ref_processor = rp;
1.40 + assert(rp != NULL, "should be non-NULL");
1.41 +
1.42 + // When collecting the permanent generation methodOops may be moving,
1.43 + // so we either have to flush all bcp data or convert it into bci.
1.44 + CodeCache::gc_prologue();
1.45 + Threads::gc_prologue();
1.46 +
1.47 + // Increment the invocation count for the permanent generation, since it is
1.48 + // implicitly collected whenever we do a full mark sweep collection.
1.49 + SharedHeap* sh = SharedHeap::heap();
1.50 + sh->perm_gen()->stat_record()->invocations++;
1.51 +
1.52 + bool marked_for_unloading = false;
1.53 +
1.54 + allocate_stacks();
1.55 +
1.56 + mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
1.57 +
1.58 + if (G1VerifyConcMark) {
1.59 + G1CollectedHeap* g1h = G1CollectedHeap::heap();
1.60 + g1h->checkConcurrentMark();
1.61 + }
1.62 +
1.63 + mark_sweep_phase2();
1.64 +
1.65 + // Don't add any more derived pointers during phase3
1.66 + COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
1.67 +
1.68 + mark_sweep_phase3();
1.69 +
1.70 + mark_sweep_phase4();
1.71 +
1.72 + GenMarkSweep::restore_marks();
1.73 +
1.74 + GenMarkSweep::deallocate_stacks();
1.75 +
1.76 + // We must invalidate the perm-gen rs, so that it gets rebuilt.
1.77 + GenRemSet* rs = sh->rem_set();
1.78 + rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/);
1.79 +
1.80 + // "free at last gc" is calculated from these.
1.81 + // CHF: cheating for now!!!
1.82 + // Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
1.83 + // Universe::set_heap_used_at_last_gc(Universe::heap()->used());
1.84 +
1.85 + Threads::gc_epilogue();
1.86 + CodeCache::gc_epilogue();
1.87 +
1.88 + // refs processing: clean slate
1.89 + GenMarkSweep::_ref_processor = NULL;
1.90 +}
1.91 +
1.92 +
1.93 +void G1MarkSweep::allocate_stacks() {
1.94 + GenMarkSweep::_preserved_count_max = 0;
1.95 + GenMarkSweep::_preserved_marks = NULL;
1.96 + GenMarkSweep::_preserved_count = 0;
1.97 + GenMarkSweep::_preserved_mark_stack = NULL;
1.98 + GenMarkSweep::_preserved_oop_stack = NULL;
1.99 +
1.100 + GenMarkSweep::_marking_stack =
1.101 + new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
1.102 +
1.103 + size_t size = SystemDictionary::number_of_classes() * 2;
1.104 + GenMarkSweep::_revisit_klass_stack =
1.105 + new (ResourceObj::C_HEAP) GrowableArray<Klass*>((int)size, true);
1.106 +}
1.107 +
1.108 +void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
1.109 + bool clear_all_softrefs) {
1.110 + // Recursively traverse all live objects and mark them
1.111 + EventMark m("1 mark object");
1.112 + TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
1.113 + GenMarkSweep::trace(" 1");
1.114 +
1.115 + SharedHeap* sh = SharedHeap::heap();
1.116 +
1.117 + sh->process_strong_roots(true, // Collecting permanent generation.
1.118 + SharedHeap::SO_SystemClasses,
1.119 + &GenMarkSweep::follow_root_closure,
1.120 + &GenMarkSweep::follow_root_closure);
1.121 +
1.122 + // Process reference objects found during marking
1.123 + ReferencePolicy *soft_ref_policy;
1.124 + if (clear_all_softrefs) {
1.125 + soft_ref_policy = new AlwaysClearPolicy();
1.126 + } else {
1.127 +#ifdef COMPILER2
1.128 + soft_ref_policy = new LRUMaxHeapPolicy();
1.129 +#else
1.130 + soft_ref_policy = new LRUCurrentHeapPolicy();
1.131 +#endif
1.132 + }
1.133 + assert(soft_ref_policy != NULL,"No soft reference policy");
1.134 + GenMarkSweep::ref_processor()->process_discovered_references(
1.135 + soft_ref_policy,
1.136 + &GenMarkSweep::is_alive,
1.137 + &GenMarkSweep::keep_alive,
1.138 + &GenMarkSweep::follow_stack_closure,
1.139 + NULL);
1.140 +
1.141 + // Follow system dictionary roots and unload classes
1.142 + bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
1.143 + assert(GenMarkSweep::_marking_stack->is_empty(),
1.144 + "stack should be empty by now");
1.145 +
1.146 + // Follow code cache roots (has to be done after system dictionary,
1.147 + // assumes all live klasses are marked)
1.148 + CodeCache::do_unloading(&GenMarkSweep::is_alive,
1.149 + &GenMarkSweep::keep_alive,
1.150 + purged_class);
1.151 + GenMarkSweep::follow_stack();
1.152 +
1.153 + // Update subklass/sibling/implementor links of live klasses
1.154 + GenMarkSweep::follow_weak_klass_links();
1.155 + assert(GenMarkSweep::_marking_stack->is_empty(),
1.156 + "stack should be empty by now");
1.157 +
1.158 + // Visit symbol and interned string tables and delete unmarked oops
1.159 + SymbolTable::unlink(&GenMarkSweep::is_alive);
1.160 + StringTable::unlink(&GenMarkSweep::is_alive);
1.161 +
1.162 + assert(GenMarkSweep::_marking_stack->is_empty(),
1.163 + "stack should be empty by now");
1.164 +}
1.165 +
1.166 +class G1PrepareCompactClosure: public HeapRegionClosure {
1.167 + ModRefBarrierSet* _mrbs;
1.168 + CompactPoint _cp;
1.169 + bool _popular_only;
1.170 +
1.171 + void free_humongous_region(HeapRegion* hr) {
1.172 + HeapWord* bot = hr->bottom();
1.173 + HeapWord* end = hr->end();
1.174 + assert(hr->startsHumongous(),
1.175 + "Only the start of a humongous region should be freed.");
1.176 + G1CollectedHeap::heap()->free_region(hr);
1.177 + hr->prepare_for_compaction(&_cp);
1.178 + // Also clear the part of the card table that will be unused after
1.179 + // compaction.
1.180 + _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
1.181 + }
1.182 +
1.183 +public:
1.184 + G1PrepareCompactClosure(CompactibleSpace* cs, bool popular_only) :
1.185 + _cp(NULL, cs, cs->initialize_threshold()),
1.186 + _mrbs(G1CollectedHeap::heap()->mr_bs()),
1.187 + _popular_only(popular_only)
1.188 + {}
1.189 + bool doHeapRegion(HeapRegion* hr) {
1.190 + if (_popular_only && !hr->popular())
1.191 + return true; // terminate early
1.192 + else if (!_popular_only && hr->popular())
1.193 + return false; // skip this one.
1.194 +
1.195 + if (hr->isHumongous()) {
1.196 + if (hr->startsHumongous()) {
1.197 + oop obj = oop(hr->bottom());
1.198 + if (obj->is_gc_marked()) {
1.199 + obj->forward_to(obj);
1.200 + } else {
1.201 + free_humongous_region(hr);
1.202 + }
1.203 + } else {
1.204 + assert(hr->continuesHumongous(), "Invalid humongous.");
1.205 + }
1.206 + } else {
1.207 + hr->prepare_for_compaction(&_cp);
1.208 + // Also clear the part of the card table that will be unused after
1.209 + // compaction.
1.210 + _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
1.211 + }
1.212 + return false;
1.213 + }
1.214 +};
1.215 +// Stolen verbatim from g1CollectedHeap.cpp
1.216 +class FindFirstRegionClosure: public HeapRegionClosure {
1.217 + HeapRegion* _a_region;
1.218 + bool _find_popular;
1.219 +public:
1.220 + FindFirstRegionClosure(bool find_popular) :
1.221 + _a_region(NULL), _find_popular(find_popular) {}
1.222 + bool doHeapRegion(HeapRegion* r) {
1.223 + if (r->popular() == _find_popular) {
1.224 + _a_region = r;
1.225 + return true;
1.226 + } else {
1.227 + return false;
1.228 + }
1.229 + }
1.230 + HeapRegion* result() { return _a_region; }
1.231 +};
1.232 +
1.233 +void G1MarkSweep::mark_sweep_phase2() {
1.234 + // Now all live objects are marked, compute the new object addresses.
1.235 +
1.236 + // It is imperative that we traverse perm_gen LAST. If dead space is
1.237 + // allowed a range of dead object may get overwritten by a dead int
1.238 + // array. If perm_gen is not traversed last a klassOop may get
1.239 + // overwritten. This is fine since it is dead, but if the class has dead
1.240 + // instances we have to skip them, and in order to find their size we
1.241 + // need the klassOop!
1.242 + //
1.243 + // It is not required that we traverse spaces in the same order in
1.244 + // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
1.245 + // tracking expects us to do so. See comment under phase4.
1.246 +
1.247 + G1CollectedHeap* g1h = G1CollectedHeap::heap();
1.248 + Generation* pg = g1h->perm_gen();
1.249 +
1.250 + EventMark m("2 compute new addresses");
1.251 + TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
1.252 + GenMarkSweep::trace("2");
1.253 +
1.254 + // First we compact the popular regions.
1.255 + if (G1NumPopularRegions > 0) {
1.256 + CompactibleSpace* sp = g1h->first_compactible_space();
1.257 + FindFirstRegionClosure cl(true /*find_popular*/);
1.258 + g1h->heap_region_iterate(&cl);
1.259 + HeapRegion *r = cl.result();
1.260 + assert(r->popular(), "should have found a popular region.");
1.261 + assert(r == sp, "first popular heap region should "
1.262 + "== first compactible space");
1.263 + G1PrepareCompactClosure blk(sp, true/*popular_only*/);
1.264 + g1h->heap_region_iterate(&blk);
1.265 + }
1.266 +
1.267 + // Now we do the regular regions.
1.268 + FindFirstRegionClosure cl(false /*find_popular*/);
1.269 + g1h->heap_region_iterate(&cl);
1.270 + HeapRegion *r = cl.result();
1.271 + assert(!r->popular(), "should have founda non-popular region.");
1.272 + CompactibleSpace* sp = r;
1.273 + if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
1.274 + sp = r->next_compaction_space();
1.275 + }
1.276 +
1.277 + G1PrepareCompactClosure blk(sp, false/*popular_only*/);
1.278 + g1h->heap_region_iterate(&blk);
1.279 +
1.280 + CompactPoint perm_cp(pg, NULL, NULL);
1.281 + pg->prepare_for_compaction(&perm_cp);
1.282 +}
1.283 +
1.284 +class G1AdjustPointersClosure: public HeapRegionClosure {
1.285 + public:
1.286 + bool doHeapRegion(HeapRegion* r) {
1.287 + if (r->isHumongous()) {
1.288 + if (r->startsHumongous()) {
1.289 + // We must adjust the pointers on the single H object.
1.290 + oop obj = oop(r->bottom());
1.291 + debug_only(GenMarkSweep::track_interior_pointers(obj));
1.292 + // point all the oops to the new location
1.293 + obj->adjust_pointers();
1.294 + debug_only(GenMarkSweep::check_interior_pointers());
1.295 + }
1.296 + } else {
1.297 + // This really ought to be "as_CompactibleSpace"...
1.298 + r->adjust_pointers();
1.299 + }
1.300 + return false;
1.301 + }
1.302 +};
1.303 +
1.304 +void G1MarkSweep::mark_sweep_phase3() {
1.305 + G1CollectedHeap* g1h = G1CollectedHeap::heap();
1.306 + Generation* pg = g1h->perm_gen();
1.307 +
1.308 + // Adjust the pointers to reflect the new locations
1.309 + EventMark m("3 adjust pointers");
1.310 + TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
1.311 + GenMarkSweep::trace("3");
1.312 +
1.313 + SharedHeap* sh = SharedHeap::heap();
1.314 +
1.315 + sh->process_strong_roots(true, // Collecting permanent generation.
1.316 + SharedHeap::SO_AllClasses,
1.317 + &GenMarkSweep::adjust_root_pointer_closure,
1.318 + &GenMarkSweep::adjust_pointer_closure);
1.319 +
1.320 + g1h->ref_processor()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure);
1.321 +
1.322 + // Now adjust pointers in remaining weak roots. (All of which should
1.323 + // have been cleared if they pointed to non-surviving objects.)
1.324 + g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure,
1.325 + &GenMarkSweep::adjust_pointer_closure);
1.326 +
1.327 + GenMarkSweep::adjust_marks();
1.328 +
1.329 + G1AdjustPointersClosure blk;
1.330 + g1h->heap_region_iterate(&blk);
1.331 + pg->adjust_pointers();
1.332 +}
1.333 +
1.334 +class G1SpaceCompactClosure: public HeapRegionClosure {
1.335 +public:
1.336 + G1SpaceCompactClosure() {}
1.337 +
1.338 + bool doHeapRegion(HeapRegion* hr) {
1.339 + if (hr->isHumongous()) {
1.340 + if (hr->startsHumongous()) {
1.341 + oop obj = oop(hr->bottom());
1.342 + if (obj->is_gc_marked()) {
1.343 + obj->init_mark();
1.344 + } else {
1.345 + assert(hr->is_empty(), "Should have been cleared in phase 2.");
1.346 + }
1.347 + hr->reset_during_compaction();
1.348 + }
1.349 + } else {
1.350 + hr->compact();
1.351 + }
1.352 + return false;
1.353 + }
1.354 +};
1.355 +
1.356 +void G1MarkSweep::mark_sweep_phase4() {
1.357 + // All pointers are now adjusted, move objects accordingly
1.358 +
1.359 + // It is imperative that we traverse perm_gen first in phase4. All
1.360 + // classes must be allocated earlier than their instances, and traversing
1.361 + // perm_gen first makes sure that all klassOops have moved to their new
1.362 + // location before any instance does a dispatch through it's klass!
1.363 +
1.364 + // The ValidateMarkSweep live oops tracking expects us to traverse spaces
1.365 + // in the same order in phase2, phase3 and phase4. We don't quite do that
1.366 + // here (perm_gen first rather than last), so we tell the validate code
1.367 + // to use a higher index (saved from phase2) when verifying perm_gen.
1.368 + G1CollectedHeap* g1h = G1CollectedHeap::heap();
1.369 + Generation* pg = g1h->perm_gen();
1.370 +
1.371 + EventMark m("4 compact heap");
1.372 + TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
1.373 + GenMarkSweep::trace("4");
1.374 +
1.375 + pg->compact();
1.376 +
1.377 + G1SpaceCompactClosure blk;
1.378 + g1h->heap_region_iterate(&blk);
1.379 +
1.380 +}
1.381 +
1.382 +// Local Variables: ***
1.383 +// c-indentation-style: gnu ***
1.384 +// End: ***
