rev 5892 : imported patch moveStringsProcessing

   1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
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  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/javaClasses.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "code/codeCache.hpp"
  31 #include "code/icBuffer.hpp"
  32 #include "gc_implementation/g1/g1Log.hpp"
  33 #include "gc_implementation/g1/g1MarkSweep.hpp"
  34 #include "gc_implementation/shared/gcHeapSummary.hpp"
  35 #include "gc_implementation/shared/gcTimer.hpp"
  36 #include "gc_implementation/shared/gcTrace.hpp"
  37 #include "gc_implementation/shared/gcTraceTime.hpp"
  38 #include "memory/gcLocker.hpp"
  39 #include "memory/genCollectedHeap.hpp"
  40 #include "memory/modRefBarrierSet.hpp"
  41 #include "memory/referencePolicy.hpp"
  42 #include "memory/space.hpp"
  43 #include "oops/instanceRefKlass.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "prims/jvmtiExport.hpp"
  46 #include "runtime/biasedLocking.hpp"
  47 #include "runtime/fprofiler.hpp"
  48 #include "runtime/synchronizer.hpp"
  49 #include "runtime/thread.hpp"
  50 #include "runtime/vmThread.hpp"
  51 #include "utilities/copy.hpp"
  52 #include "utilities/events.hpp"
  53 
  54 class HeapRegion;
  55 
  56 void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
  57                                       bool clear_all_softrefs) {
  58   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
  59 
  60   SharedHeap* sh = SharedHeap::heap();
  61 #ifdef ASSERT
  62   if (sh->collector_policy()->should_clear_all_soft_refs()) {
  63     assert(clear_all_softrefs, "Policy should have been checked earler");
  64   }
  65 #endif
  66   // hook up weak ref data so it can be used during Mark-Sweep
  67   assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
  68   assert(rp != NULL, "should be non-NULL");
  69   assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
  70 
  71   GenMarkSweep::_ref_processor = rp;
  72   rp->setup_policy(clear_all_softrefs);
  73 
  74   // When collecting the permanent generation Method*s may be moving,
  75   // so we either have to flush all bcp data or convert it into bci.
  76   CodeCache::gc_prologue();
  77   Threads::gc_prologue();
  78 
  79   bool marked_for_unloading = false;
  80 
  81   allocate_stacks();
  82 
  83   // We should save the marks of the currently locked biased monitors.
  84   // The marking doesn't preserve the marks of biased objects.
  85   BiasedLocking::preserve_marks();
  86 
  87   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
  88 
  89   mark_sweep_phase2();
  90 
  91   // Don't add any more derived pointers during phase3
  92   COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
  93 
  94   mark_sweep_phase3();
  95 
  96   mark_sweep_phase4();
  97 
  98   GenMarkSweep::restore_marks();
  99   BiasedLocking::restore_marks();
 100   GenMarkSweep::deallocate_stacks();
 101 
 102   // "free at last gc" is calculated from these.
 103   // CHF: cheating for now!!!
 104   //  Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
 105   //  Universe::set_heap_used_at_last_gc(Universe::heap()->used());
 106 
 107   Threads::gc_epilogue();
 108   CodeCache::gc_epilogue();
 109   JvmtiExport::gc_epilogue();
 110 
 111   // refs processing: clean slate
 112   GenMarkSweep::_ref_processor = NULL;
 113 }
 114 
 115 
 116 void G1MarkSweep::allocate_stacks() {
 117   GenMarkSweep::_preserved_count_max = 0;
 118   GenMarkSweep::_preserved_marks = NULL;
 119   GenMarkSweep::_preserved_count = 0;
 120 }
 121 
 122 void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
 123                                     bool clear_all_softrefs) {
 124   // Recursively traverse all live objects and mark them
 125   GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer());
 126   GenMarkSweep::trace(" 1");
 127 
 128   SharedHeap* sh = SharedHeap::heap();
 129 
 130   // Need cleared claim bits for the strong roots processing
 131   ClassLoaderDataGraph::clear_claimed_marks();
 132 
 133   sh->process_strong_roots(true,  // activate StrongRootsScope
 134                            SharedHeap::SO_SystemClasses,
 135                            &GenMarkSweep::follow_root_closure,
 136                            &GenMarkSweep::follow_klass_closure);
 137 
 138   // Process reference objects found during marking
 139   ReferenceProcessor* rp = GenMarkSweep::ref_processor();
 140   assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity");
 141 
 142   rp->setup_policy(clear_all_softrefs);
 143   const ReferenceProcessorStats& stats =
 144     rp->process_discovered_references(&GenMarkSweep::is_alive,
 145                                       &GenMarkSweep::keep_alive,
 146                                       &GenMarkSweep::follow_stack_closure,
 147                                       NULL,
 148                                       gc_timer());
 149   gc_tracer()->report_gc_reference_stats(stats);
 150 
 151 
 152   // This is the point where the entire marking should have completed.
 153   assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
 154 
 155   // Unload classes and purge the SystemDictionary.
 156   bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
 157 
 158   // Unload nmethods.
 159   CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
 160 
 161   // Prune dead klasses from subklass/sibling/implementor lists.
 162   Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
 163 
 164   // Delete entries for dead interned string and clean up unreferenced symbols in symbol table.
 165   G1CollectedHeap::heap()->unlink_string_and_symbol_table(&GenMarkSweep::is_alive);
 166 
 167   if (VerifyDuringGC) {
 168     HandleMark hm;  // handle scope
 169     COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
 170     Universe::heap()->prepare_for_verify();
 171     // Note: we can verify only the heap here. When an object is
 172     // marked, the previous value of the mark word (including
 173     // identity hash values, ages, etc) is preserved, and the mark
 174     // word is set to markOop::marked_value - effectively removing
 175     // any hash values from the mark word. These hash values are
 176     // used when verifying the dictionaries and so removing them
 177     // from the mark word can make verification of the dictionaries
 178     // fail. At the end of the GC, the original mark word values
 179     // (including hash values) are restored to the appropriate
 180     // objects.
 181     if (!VerifySilently) {
 182       gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
 183     }
 184     Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord);
 185     if (!VerifySilently) {
 186       gclog_or_tty->print_cr("]");
 187     }
 188   }
 189 
 190   gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive);
 191 }
 192 
 193 class G1PrepareCompactClosure: public HeapRegionClosure {
 194   G1CollectedHeap* _g1h;
 195   ModRefBarrierSet* _mrbs;
 196   CompactPoint _cp;
 197   HumongousRegionSet _humongous_proxy_set;
 198 
 199   void free_humongous_region(HeapRegion* hr) {
 200     HeapWord* end = hr->end();
 201     size_t dummy_pre_used;
 202     FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
 203 
 204     assert(hr->startsHumongous(),
 205            "Only the start of a humongous region should be freed.");
 206     _g1h->free_humongous_region(hr, &dummy_pre_used, &dummy_free_list,
 207                                 &_humongous_proxy_set, false /* par */);
 208     hr->prepare_for_compaction(&_cp);
 209     // Also clear the part of the card table that will be unused after
 210     // compaction.
 211     _mrbs->clear(MemRegion(hr->compaction_top(), end));
 212     dummy_free_list.remove_all();
 213   }
 214 
 215 public:
 216   G1PrepareCompactClosure(CompactibleSpace* cs)
 217   : _g1h(G1CollectedHeap::heap()),
 218     _mrbs(_g1h->g1_barrier_set()),
 219     _cp(NULL, cs, cs->initialize_threshold()),
 220     _humongous_proxy_set("G1MarkSweep Humongous Proxy Set") { }
 221 
 222   void update_sets() {
 223     // We'll recalculate total used bytes and recreate the free list
 224     // at the end of the GC, so no point in updating those values here.
 225     _g1h->update_sets_after_freeing_regions(0, /* pre_used */
 226                                             NULL, /* free_list */
 227                                             NULL, /* old_proxy_set */
 228                                             &_humongous_proxy_set,
 229                                             false /* par */);
 230   }
 231 
 232   bool doHeapRegion(HeapRegion* hr) {
 233     if (hr->isHumongous()) {
 234       if (hr->startsHumongous()) {
 235         oop obj = oop(hr->bottom());
 236         if (obj->is_gc_marked()) {
 237           obj->forward_to(obj);
 238         } else  {
 239           free_humongous_region(hr);
 240         }
 241       } else {
 242         assert(hr->continuesHumongous(), "Invalid humongous.");
 243       }
 244     } else {
 245       hr->prepare_for_compaction(&_cp);
 246       // Also clear the part of the card table that will be unused after
 247       // compaction.
 248       _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
 249     }
 250     return false;
 251   }
 252 };
 253 
 254 void G1MarkSweep::mark_sweep_phase2() {
 255   // Now all live objects are marked, compute the new object addresses.
 256 
 257   // It is not required that we traverse spaces in the same order in
 258   // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
 259   // tracking expects us to do so. See comment under phase4.
 260 
 261   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 262 
 263   GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer());
 264   GenMarkSweep::trace("2");
 265 
 266   // find the first region
 267   HeapRegion* r = g1h->region_at(0);
 268   CompactibleSpace* sp = r;
 269   if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
 270     sp = r->next_compaction_space();
 271   }
 272 
 273   G1PrepareCompactClosure blk(sp);
 274   g1h->heap_region_iterate(&blk);
 275   blk.update_sets();
 276 }
 277 
 278 class G1AdjustPointersClosure: public HeapRegionClosure {
 279  public:
 280   bool doHeapRegion(HeapRegion* r) {
 281     if (r->isHumongous()) {
 282       if (r->startsHumongous()) {
 283         // We must adjust the pointers on the single H object.
 284         oop obj = oop(r->bottom());
 285         // point all the oops to the new location
 286         obj->adjust_pointers();
 287       }
 288     } else {
 289       // This really ought to be "as_CompactibleSpace"...
 290       r->adjust_pointers();
 291     }
 292     return false;
 293   }
 294 };
 295 
 296 void G1MarkSweep::mark_sweep_phase3() {
 297   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 298 
 299   // Adjust the pointers to reflect the new locations
 300   GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer());
 301   GenMarkSweep::trace("3");
 302 
 303   SharedHeap* sh = SharedHeap::heap();
 304 
 305   // Need cleared claim bits for the strong roots processing
 306   ClassLoaderDataGraph::clear_claimed_marks();
 307 
 308   sh->process_strong_roots(true,  // activate StrongRootsScope
 309                            SharedHeap::SO_AllClasses | SharedHeap::SO_AllCodeCache,
 310                            &GenMarkSweep::adjust_pointer_closure,
 311                            &GenMarkSweep::adjust_klass_closure);
 312 
 313   assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
 314   g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
 315 
 316   // Now adjust pointers in remaining weak roots.  (All of which should
 317   // have been cleared if they pointed to non-surviving objects.)
 318   sh->process_weak_roots(&GenMarkSweep::adjust_pointer_closure);
 319 
 320   GenMarkSweep::adjust_marks();
 321 
 322   G1AdjustPointersClosure blk;
 323   g1h->heap_region_iterate(&blk);
 324 }
 325 
 326 class G1SpaceCompactClosure: public HeapRegionClosure {
 327 public:
 328   G1SpaceCompactClosure() {}
 329 
 330   bool doHeapRegion(HeapRegion* hr) {
 331     if (hr->isHumongous()) {
 332       if (hr->startsHumongous()) {
 333         oop obj = oop(hr->bottom());
 334         if (obj->is_gc_marked()) {
 335           obj->init_mark();
 336         } else {
 337           assert(hr->is_empty(), "Should have been cleared in phase 2.");
 338         }
 339         hr->reset_during_compaction();
 340       }
 341     } else {
 342       hr->compact();
 343     }
 344     return false;
 345   }
 346 };
 347 
 348 void G1MarkSweep::mark_sweep_phase4() {
 349   // All pointers are now adjusted, move objects accordingly
 350 
 351   // The ValidateMarkSweep live oops tracking expects us to traverse spaces
 352   // in the same order in phase2, phase3 and phase4. We don't quite do that
 353   // here (code and comment not fixed for perm removal), so we tell the validate code
 354   // to use a higher index (saved from phase2) when verifying perm_gen.
 355   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 356 
 357   GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer());
 358   GenMarkSweep::trace("4");
 359 
 360   G1SpaceCompactClosure blk;
 361   g1h->heap_region_iterate(&blk);
 362 
 363 }
--- EOF ---