psMarkSweep.cpp 23.7 KB
Newer Older
D
duke 已提交
1
/*
2
 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
D
duke 已提交
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
 * 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.
 *
19 20 21
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
D
duke 已提交
22 23 24
 *
 */

25 26 27 28 29 30 31 32 33 34 35 36 37
#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "code/codeCache.hpp"
#include "gc_implementation/parallelScavenge/generationSizer.hpp"
#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
#include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
#include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
#include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
#include "gc_implementation/parallelScavenge/psOldGen.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.hpp"
#include "gc_implementation/parallelScavenge/psYoungGen.hpp"
#include "gc_implementation/shared/isGCActiveMark.hpp"
38
#include "gc_implementation/shared/markSweep.hpp"
39 40 41 42 43 44 45 46 47 48 49 50 51 52
#include "gc_implementation/shared/spaceDecorator.hpp"
#include "gc_interface/gcCause.hpp"
#include "memory/gcLocker.inline.hpp"
#include "memory/referencePolicy.hpp"
#include "memory/referenceProcessor.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/vmThread.hpp"
#include "services/management.hpp"
#include "services/memoryService.hpp"
#include "utilities/events.hpp"
#include "utilities/stack.inline.hpp"
D
duke 已提交
53 54 55 56 57 58 59

elapsedTimer        PSMarkSweep::_accumulated_time;
jlong               PSMarkSweep::_time_of_last_gc   = 0;
CollectorCounters*  PSMarkSweep::_counters = NULL;

void PSMarkSweep::initialize() {
  MemRegion mr = Universe::heap()->reserved_region();
60
  _ref_processor = new ReferenceProcessor(mr);     // a vanilla ref proc
61
  _counters = new CollectorCounters("PSMarkSweep", 1);
D
duke 已提交
62 63 64 65 66 67 68 69 70 71
}

// This method contains all heap specific policy for invoking mark sweep.
// PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact
// the heap. It will do nothing further. If we need to bail out for policy
// reasons, scavenge before full gc, or any other specialized behavior, it
// needs to be added here.
//
// Note that this method should only be called from the vm_thread while
// at a safepoint!
72 73 74 75 76 77
//
// Note that the all_soft_refs_clear flag in the collector policy
// may be true because this method can be called without intervening
// activity.  For example when the heap space is tight and full measure
// are being taken to free space.

D
duke 已提交
78 79 80 81 82 83 84 85
void PSMarkSweep::invoke(bool maximum_heap_compaction) {
  assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
  assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
  assert(!Universe::heap()->is_gc_active(), "not reentrant");

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  GCCause::Cause gc_cause = heap->gc_cause();
  PSAdaptiveSizePolicy* policy = heap->size_policy();
86
  IsGCActiveMark mark;
D
duke 已提交
87

88 89
  if (ScavengeBeforeFullGC) {
    PSScavenge::invoke_no_policy();
D
duke 已提交
90
  }
91 92 93 94 95 96 97

  const bool clear_all_soft_refs =
    heap->collector_policy()->should_clear_all_soft_refs();

  int count = (maximum_heap_compaction)?1:MarkSweepAlwaysCompactCount;
  IntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count);
  PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction);
D
duke 已提交
98 99 100 101
}

// This method contains no policy. You should probably
// be calling invoke() instead.
102
bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
D
duke 已提交
103 104 105 106
  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
  assert(ref_processor() != NULL, "Sanity");

  if (GC_locker::check_active_before_gc()) {
107
    return false;
D
duke 已提交
108 109 110 111 112 113 114
  }

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  GCCause::Cause gc_cause = heap->gc_cause();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  PSAdaptiveSizePolicy* size_policy = heap->size_policy();

115 116 117 118
  // The scope of casr should end after code that can change
  // CollectorPolicy::_should_clear_all_soft_refs.
  ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy());

D
duke 已提交
119 120 121 122 123 124
  PSYoungGen* young_gen = heap->young_gen();
  PSOldGen* old_gen = heap->old_gen();

  // Increment the invocation count
  heap->increment_total_collections(true /* full */);

125 126 127
  // Save information needed to minimize mangling
  heap->record_gen_tops_before_GC();

D
duke 已提交
128 129 130 131 132
  // We need to track unique mark sweep invocations as well.
  _total_invocations++;

  AdaptiveSizePolicyOutput(size_policy, heap->total_collections());

133
  heap->print_heap_before_gc();
D
duke 已提交
134 135 136 137 138 139 140 141

  // Fill in TLABs
  heap->accumulate_statistics_all_tlabs();
  heap->ensure_parsability(true);  // retire TLABs

  if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
    HandleMark hm;  // Discard invalid handles created during verification
    gclog_or_tty->print(" VerifyBeforeGC:");
142
    Universe::verify();
D
duke 已提交
143 144 145 146 147 148 149 150
  }

  // Verify object start arrays
  if (VerifyObjectStartArray &&
      VerifyBeforeGC) {
    old_gen->verify_object_start_array();
  }

151 152
  heap->pre_full_gc_dump();

D
duke 已提交
153 154 155 156 157 158 159
  // Filled in below to track the state of the young gen after the collection.
  bool eden_empty;
  bool survivors_empty;
  bool young_gen_empty;

  {
    HandleMark hm;
160

D
duke 已提交
161 162
    gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
    TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
163
    TraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty);
D
duke 已提交
164
    TraceCollectorStats tcs(counters());
165
    TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
D
duke 已提交
166 167 168 169 170 171 172 173 174 175 176 177 178

    if (TraceGen1Time) accumulated_time()->start();

    // Let the size policy know we're starting
    size_policy->major_collection_begin();

    CodeCache::gc_prologue();
    Threads::gc_prologue();
    BiasedLocking::preserve_marks();

    // Capture heap size before collection for printing.
    size_t prev_used = heap->used();

179 180
    // Capture metadata size before collection for sizing.
    size_t metadata_prev_used = MetaspaceAux::used_in_bytes();
D
duke 已提交
181 182 183 184 185 186 187 188 189

    // For PrintGCDetails
    size_t old_gen_prev_used = old_gen->used_in_bytes();
    size_t young_gen_prev_used = young_gen->used_in_bytes();

    allocate_stacks();

    COMPILER2_PRESENT(DerivedPointerTable::clear());

190
    ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
191
    ref_processor()->setup_policy(clear_all_softrefs);
D
duke 已提交
192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208

    mark_sweep_phase1(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();

    mark_sweep_phase4();

    restore_marks();

    deallocate_stacks();

209 210 211 212 213 214
    if (ZapUnusedHeapArea) {
      // Do a complete mangle (top to end) because the usage for
      // scratch does not maintain a top pointer.
      young_gen->to_space()->mangle_unused_area_complete();
    }

D
duke 已提交
215 216 217 218 219 220 221 222 223 224
    eden_empty = young_gen->eden_space()->is_empty();
    if (!eden_empty) {
      eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen);
    }

    // Update heap occupancy information which is used as
    // input to soft ref clearing policy at the next gc.
    Universe::update_heap_info_at_gc();

    survivors_empty = young_gen->from_space()->is_empty() &&
225
                      young_gen->to_space()->is_empty();
D
duke 已提交
226 227 228 229 230 231 232
    young_gen_empty = eden_empty && survivors_empty;

    BarrierSet* bs = heap->barrier_set();
    if (bs->is_a(BarrierSet::ModRef)) {
      ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
      MemRegion old_mr = heap->old_gen()->reserved();
      if (young_gen_empty) {
233
        modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
D
duke 已提交
234
      } else {
235
        modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
D
duke 已提交
236 237 238
      }
    }

239 240 241
    // Delete metaspaces for unloaded class loaders and clean up loader_data graph
    ClassLoaderDataGraph::purge();

D
duke 已提交
242 243 244
    BiasedLocking::restore_marks();
    Threads::gc_epilogue();
    CodeCache::gc_epilogue();
245
    JvmtiExport::gc_epilogue();
D
duke 已提交
246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264

    COMPILER2_PRESENT(DerivedPointerTable::update_pointers());

    ref_processor()->enqueue_discovered_references(NULL);

    // Update time of last GC
    reset_millis_since_last_gc();

    // Let the size policy know we're done
    size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);

    if (UseAdaptiveSizePolicy) {

      if (PrintAdaptiveSizePolicy) {
        gclog_or_tty->print("AdaptiveSizeStart: ");
        gclog_or_tty->stamp();
        gclog_or_tty->print_cr(" collection: %d ",
                       heap->total_collections());
        if (Verbose) {
265 266
          gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
            old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
D
duke 已提交
267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289
        }
      }

      // Don't check if the size_policy is ready here.  Let
      // the size_policy check that internally.
      if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
          ((gc_cause != GCCause::_java_lang_system_gc) ||
            UseAdaptiveSizePolicyWithSystemGC)) {
        // Calculate optimal free space amounts
        assert(young_gen->max_size() >
          young_gen->from_space()->capacity_in_bytes() +
          young_gen->to_space()->capacity_in_bytes(),
          "Sizes of space in young gen are out-of-bounds");
        size_t max_eden_size = young_gen->max_size() -
          young_gen->from_space()->capacity_in_bytes() -
          young_gen->to_space()->capacity_in_bytes();
        size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
                                 young_gen->eden_space()->used_in_bytes(),
                                 old_gen->used_in_bytes(),
                                 young_gen->eden_space()->capacity_in_bytes(),
                                 old_gen->max_gen_size(),
                                 max_eden_size,
                                 true /* full gc*/,
290 291
                                 gc_cause,
                                 heap->collector_policy());
D
duke 已提交
292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317

        heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());

        // Don't resize the young generation at an major collection.  A
        // desired young generation size may have been calculated but
        // resizing the young generation complicates the code because the
        // resizing of the old generation may have moved the boundary
        // between the young generation and the old generation.  Let the
        // young generation resizing happen at the minor collections.
      }
      if (PrintAdaptiveSizePolicy) {
        gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
                       heap->total_collections());
      }
    }

    if (UsePerfData) {
      heap->gc_policy_counters()->update_counters();
      heap->gc_policy_counters()->update_old_capacity(
        old_gen->capacity_in_bytes());
      heap->gc_policy_counters()->update_young_capacity(
        young_gen->capacity_in_bytes());
    }

    heap->resize_all_tlabs();

318 319
    // We collected the heap, recalculate the metaspace capacity
    MetaspaceGC::compute_new_size();
D
duke 已提交
320 321 322 323 324 325 326 327 328 329 330 331

    if (TraceGen1Time) accumulated_time()->stop();

    if (PrintGC) {
      if (PrintGCDetails) {
        // Don't print a GC timestamp here.  This is after the GC so
        // would be confusing.
        young_gen->print_used_change(young_gen_prev_used);
        old_gen->print_used_change(old_gen_prev_used);
      }
      heap->print_heap_change(prev_used);
      if (PrintGCDetails) {
332
        MetaspaceAux::print_metaspace_change(metadata_prev_used);
D
duke 已提交
333 334 335 336 337 338 339 340 341 342 343
      }
    }

    // Track memory usage and detect low memory
    MemoryService::track_memory_usage();
    heap->update_counters();
  }

  if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
    HandleMark hm;  // Discard invalid handles created during verification
    gclog_or_tty->print(" VerifyAfterGC:");
344
    Universe::verify();
D
duke 已提交
345 346 347 348 349 350 351 352
  }

  // Re-verify object start arrays
  if (VerifyObjectStartArray &&
      VerifyAfterGC) {
    old_gen->verify_object_start_array();
  }

353 354 355 356
  if (ZapUnusedHeapArea) {
    old_gen->object_space()->check_mangled_unused_area_complete();
  }

D
duke 已提交
357 358
  NOT_PRODUCT(ref_processor()->verify_no_references_recorded());

359
  heap->print_heap_after_gc();
360

361 362
  heap->post_full_gc_dump();

363 364 365
#ifdef TRACESPINNING
  ParallelTaskTerminator::print_termination_counts();
#endif
366 367

  return true;
D
duke 已提交
368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394
}

bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
                                             PSYoungGen* young_gen,
                                             PSOldGen* old_gen) {
  MutableSpace* const eden_space = young_gen->eden_space();
  assert(!eden_space->is_empty(), "eden must be non-empty");
  assert(young_gen->virtual_space()->alignment() ==
         old_gen->virtual_space()->alignment(), "alignments do not match");

  if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
    return false;
  }

  // Both generations must be completely committed.
  if (young_gen->virtual_space()->uncommitted_size() != 0) {
    return false;
  }
  if (old_gen->virtual_space()->uncommitted_size() != 0) {
    return false;
  }

  // Figure out how much to take from eden.  Include the average amount promoted
  // in the total; otherwise the next young gen GC will simply bail out to a
  // full GC.
  const size_t alignment = old_gen->virtual_space()->alignment();
  const size_t eden_used = eden_space->used_in_bytes();
395
  const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
D
duke 已提交
396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
  const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
  const size_t eden_capacity = eden_space->capacity_in_bytes();

  if (absorb_size >= eden_capacity) {
    return false; // Must leave some space in eden.
  }

  const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
  if (new_young_size < young_gen->min_gen_size()) {
    return false; // Respect young gen minimum size.
  }

  if (TraceAdaptiveGCBoundary && Verbose) {
    gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
                        "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
                        "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
                        "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
                        absorb_size / K,
                        eden_capacity / K, (eden_capacity - absorb_size) / K,
                        young_gen->from_space()->used_in_bytes() / K,
                        young_gen->to_space()->used_in_bytes() / K,
                        young_gen->capacity_in_bytes() / K, new_young_size / K);
  }

  // Fill the unused part of the old gen.
  MutableSpace* const old_space = old_gen->object_space();
422 423
  HeapWord* const unused_start = old_space->top();
  size_t const unused_words = pointer_delta(old_space->end(), unused_start);
D
duke 已提交
424

425 426 427 428 429
  if (unused_words > 0) {
    if (unused_words < CollectedHeap::min_fill_size()) {
      return false;  // If the old gen cannot be filled, must give up.
    }
    CollectedHeap::fill_with_objects(unused_start, unused_words);
D
duke 已提交
430 431 432 433 434 435 436 437 438 439 440 441 442 443 444
  }

  // Take the live data from eden and set both top and end in the old gen to
  // eden top.  (Need to set end because reset_after_change() mangles the region
  // from end to virtual_space->high() in debug builds).
  HeapWord* const new_top = eden_space->top();
  old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
                                        absorb_size);
  young_gen->reset_after_change();
  old_space->set_top(new_top);
  old_space->set_end(new_top);
  old_gen->reset_after_change();

  // Update the object start array for the filler object and the data from eden.
  ObjectStartArray* const start_array = old_gen->start_array();
445 446
  for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
    start_array->allocate_block(p);
D
duke 已提交
447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475
  }

  // Could update the promoted average here, but it is not typically updated at
  // full GCs and the value to use is unclear.  Something like
  //
  // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.

  size_policy->set_bytes_absorbed_from_eden(absorb_size);
  return true;
}

void PSMarkSweep::allocate_stacks() {
  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  PSYoungGen* young_gen = heap->young_gen();

  MutableSpace* to_space = young_gen->to_space();
  _preserved_marks = (PreservedMark*)to_space->top();
  _preserved_count = 0;

  // We want to calculate the size in bytes first.
  _preserved_count_max  = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte));
  // Now divide by the size of a PreservedMark
  _preserved_count_max /= sizeof(PreservedMark);
}


void PSMarkSweep::deallocate_stacks() {
476 477 478 479
  _preserved_mark_stack.clear(true);
  _preserved_oop_stack.clear(true);
  _marking_stack.clear();
  _objarray_stack.clear(true);
D
duke 已提交
480 481 482 483 484 485 486 487 488 489
}

void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) {
  // Recursively traverse all live objects and mark them
  TraceTime tm("phase 1", PrintGCDetails && Verbose, true, gclog_or_tty);
  trace(" 1");

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

490 491 492
  // Need to clear claim bits before the tracing starts.
  ClassLoaderDataGraph::clear_claimed_marks();

D
duke 已提交
493
  // General strong roots.
494 495 496 497 498 499 500 501 502 503 504
  {
    ParallelScavengeHeap::ParStrongRootsScope psrs;
    Universe::oops_do(mark_and_push_closure());
    JNIHandles::oops_do(mark_and_push_closure());   // Global (strong) JNI handles
    CodeBlobToOopClosure each_active_code_blob(mark_and_push_closure(), /*do_marking=*/ true);
    Threads::oops_do(mark_and_push_closure(), &each_active_code_blob);
    ObjectSynchronizer::oops_do(mark_and_push_closure());
    FlatProfiler::oops_do(mark_and_push_closure());
    Management::oops_do(mark_and_push_closure());
    JvmtiExport::oops_do(mark_and_push_closure());
    SystemDictionary::always_strong_oops_do(mark_and_push_closure());
505
    ClassLoaderDataGraph::always_strong_oops_do(mark_and_push_closure(), follow_klass_closure(), true);
506 507 508
    // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
    //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure()));
  }
D
duke 已提交
509 510 511 512 513 514

  // Flush marking stack.
  follow_stack();

  // Process reference objects found during marking
  {
515
    ref_processor()->setup_policy(clear_all_softrefs);
D
duke 已提交
516
    ref_processor()->process_discovered_references(
517
      is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL);
D
duke 已提交
518 519 520 521 522 523
  }

  // Follow system dictionary roots and unload classes
  bool purged_class = SystemDictionary::do_unloading(is_alive_closure());

  // Follow code cache roots
524
  CodeCache::do_unloading(is_alive_closure(), purged_class);
D
duke 已提交
525 526 527
  follow_stack(); // Flush marking stack

  // Update subklass/sibling/implementor links of live klasses
528
  Klass::clean_weak_klass_links(&is_alive);
529
  assert(_marking_stack.is_empty(), "just drained");
Y
ysr 已提交
530

531
  // Visit interned string tables and delete unmarked oops
D
duke 已提交
532
  StringTable::unlink(is_alive_closure());
533 534
  // Clean up unreferenced symbols in symbol table.
  SymbolTable::unlink();
D
duke 已提交
535

536
  assert(_marking_stack.is_empty(), "stack should be empty by now");
D
duke 已提交
537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579
}


void PSMarkSweep::mark_sweep_phase2() {
  TraceTime tm("phase 2", PrintGCDetails && Verbose, true, gclog_or_tty);
  trace("2");

  // Now all live objects are marked, compute the new object addresses.

  // 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.

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  PSOldGen* old_gen = heap->old_gen();

  // Begin compacting into the old gen
  PSMarkSweepDecorator::set_destination_decorator_tenured();

  // This will also compact the young gen spaces.
  old_gen->precompact();
}

// This should be moved to the shared markSweep code!
class PSAlwaysTrueClosure: public BoolObjectClosure {
public:
  void do_object(oop p) { ShouldNotReachHere(); }
  bool do_object_b(oop p) { return true; }
};
static PSAlwaysTrueClosure always_true;

void PSMarkSweep::mark_sweep_phase3() {
  // Adjust the pointers to reflect the new locations
  TraceTime tm("phase 3", PrintGCDetails && Verbose, true, gclog_or_tty);
  trace("3");

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  PSYoungGen* young_gen = heap->young_gen();
  PSOldGen* old_gen = heap->old_gen();
580 581 582

  // Need to clear claim bits before the tracing starts.
  ClassLoaderDataGraph::clear_claimed_marks();
D
duke 已提交
583 584 585 586

  // General strong roots.
  Universe::oops_do(adjust_root_pointer_closure());
  JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
587
  Threads::oops_do(adjust_root_pointer_closure(), NULL);
D
duke 已提交
588 589 590 591 592 593
  ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
  FlatProfiler::oops_do(adjust_root_pointer_closure());
  Management::oops_do(adjust_root_pointer_closure());
  JvmtiExport::oops_do(adjust_root_pointer_closure());
  // SO_AllClasses
  SystemDictionary::oops_do(adjust_root_pointer_closure());
594
  ClassLoaderDataGraph::oops_do(adjust_root_pointer_closure(), adjust_klass_closure(), true);
595
  //CodeCache::scavenge_root_nmethods_oops_do(adjust_root_pointer_closure());
D
duke 已提交
596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630

  // Now adjust pointers in remaining weak roots.  (All of which should
  // have been cleared if they pointed to non-surviving objects.)
  // Global (weak) JNI handles
  JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());

  CodeCache::oops_do(adjust_pointer_closure());
  StringTable::oops_do(adjust_root_pointer_closure());
  ref_processor()->weak_oops_do(adjust_root_pointer_closure());
  PSScavenge::reference_processor()->weak_oops_do(adjust_root_pointer_closure());

  adjust_marks();

  young_gen->adjust_pointers();
  old_gen->adjust_pointers();
}

void PSMarkSweep::mark_sweep_phase4() {
  EventMark m("4 compact heap");
  TraceTime tm("phase 4", PrintGCDetails && Verbose, true, gclog_or_tty);
  trace("4");

  // All pointers are now adjusted, move objects accordingly

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

  PSYoungGen* young_gen = heap->young_gen();
  PSOldGen* old_gen = heap->old_gen();

  old_gen->compact();
  young_gen->compact();
}

jlong PSMarkSweep::millis_since_last_gc() {
631 632 633 634
  // We need a monotonically non-deccreasing time in ms but
  // os::javaTimeMillis() does not guarantee monotonicity.
  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
  jlong ret_val = now - _time_of_last_gc;
D
duke 已提交
635 636
  // XXX See note in genCollectedHeap::millis_since_last_gc().
  if (ret_val < 0) {
637
    NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
D
duke 已提交
638 639 640 641 642 643
    return 0;
  }
  return ret_val;
}

void PSMarkSweep::reset_millis_since_last_gc() {
644 645 646
  // We need a monotonically non-deccreasing time in ms but
  // os::javaTimeMillis() does not guarantee monotonicity.
  _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
D
duke 已提交
647
}