view hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp @ 26701:f8ff74a6c058

8052172: Evacuation failure handling in G1 does not evacuate all objects if -XX:-G1DeferredRSUpdate is set Summary: Remove -XX:-G1DeferredRSUpdate functionality as it is racy. During evacuation failure handling, threads where evacuation failure handling occurred may try to add remembered sets to regions which remembered sets are currently being scanned. The iterator to handle the remembered set scan does not support addition of entries during scan and so may skip valid references. Reviewed-by: iveresov, brutisso, mgerdin
author tschatzl
date Tue, 16 Sep 2014 10:28:15 +0200
parents 221296ac4359
children dbd1c3f92130
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/*
 * Copyright (c) 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP

#include "gc_implementation/g1/g1ParScanThreadState.hpp"
#include "gc_implementation/g1/g1RemSet.inline.hpp"
#include "oops/oop.inline.hpp"

template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
  assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
         "Reference should not be NULL here as such are never pushed to the task queue.");
  oop obj = oopDesc::load_decode_heap_oop_not_null(p);

  // Although we never intentionally push references outside of the collection
  // set, due to (benign) races in the claim mechanism during RSet scanning more
  // than one thread might claim the same card. So the same card may be
  // processed multiple times. So redo this check.
  G1CollectedHeap::in_cset_state_t in_cset_state = _g1h->in_cset_state(obj);
  if (in_cset_state == G1CollectedHeap::InCSet) {
    oop forwardee;
    if (obj->is_forwarded()) {
      forwardee = obj->forwardee();
    } else {
      forwardee = copy_to_survivor_space(obj);
    }
    oopDesc::encode_store_heap_oop(p, forwardee);
  } else if (in_cset_state == G1CollectedHeap::IsHumongous) {
    _g1h->set_humongous_is_live(obj);
  } else {
    assert(in_cset_state == G1CollectedHeap::InNeither,
           err_msg("In_cset_state must be InNeither here, but is %d", in_cset_state));
  }

  assert(obj != NULL, "Must be");
  update_rs(from, p, queue_num());
}

inline void G1ParScanThreadState::do_oop_partial_array(oop* p) {
  assert(has_partial_array_mask(p), "invariant");
  oop from_obj = clear_partial_array_mask(p);

  assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
  assert(from_obj->is_objArray(), "must be obj array");
  objArrayOop from_obj_array = objArrayOop(from_obj);
  // The from-space object contains the real length.
  int length                 = from_obj_array->length();

  assert(from_obj->is_forwarded(), "must be forwarded");
  oop to_obj                 = from_obj->forwardee();
  assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
  objArrayOop to_obj_array   = objArrayOop(to_obj);
  // We keep track of the next start index in the length field of the
  // to-space object.
  int next_index             = to_obj_array->length();
  assert(0 <= next_index && next_index < length,
         err_msg("invariant, next index: %d, length: %d", next_index, length));

  int start                  = next_index;
  int end                    = length;
  int remainder              = end - start;
  // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
  if (remainder > 2 * ParGCArrayScanChunk) {
    end = start + ParGCArrayScanChunk;
    to_obj_array->set_length(end);
    // Push the remainder before we process the range in case another
    // worker has run out of things to do and can steal it.
    oop* from_obj_p = set_partial_array_mask(from_obj);
    push_on_queue(from_obj_p);
  } else {
    assert(length == end, "sanity");
    // We'll process the final range for this object. Restore the length
    // so that the heap remains parsable in case of evacuation failure.
    to_obj_array->set_length(end);
  }
  _scanner.set_region(_g1h->heap_region_containing_raw(to_obj));
  // Process indexes [start,end). It will also process the header
  // along with the first chunk (i.e., the chunk with start == 0).
  // Note that at this point the length field of to_obj_array is not
  // correct given that we are using it to keep track of the next
  // start index. oop_iterate_range() (thankfully!) ignores the length
  // field and only relies on the start / end parameters.  It does
  // however return the size of the object which will be incorrect. So
  // we have to ignore it even if we wanted to use it.
  to_obj_array->oop_iterate_range(&_scanner, start, end);
}

template <class T> inline void G1ParScanThreadState::deal_with_reference(T* ref_to_scan) {
  if (!has_partial_array_mask(ref_to_scan)) {
    // Note: we can use "raw" versions of "region_containing" because
    // "obj_to_scan" is definitely in the heap, and is not in a
    // humongous region.
    HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
    do_oop_evac(ref_to_scan, r);
  } else {
    do_oop_partial_array((oop*)ref_to_scan);
  }
}

inline void G1ParScanThreadState::dispatch_reference(StarTask ref) {
  assert(verify_task(ref), "sanity");
  if (ref.is_narrow()) {
    deal_with_reference((narrowOop*)ref);
  } else {
    deal_with_reference((oop*)ref);
  }
}

void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) {
  StarTask stolen_task;
  while (task_queues->steal(queue_num(), hash_seed(), stolen_task)) {
    assert(verify_task(stolen_task), "sanity");
    dispatch_reference(stolen_task);

    // We've just processed a reference and we might have made
    // available new entries on the queues. So we have to make sure
    // we drain the queues as necessary.
    trim_queue();
  }
}

#endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1PARSCANTHREADSTATE_INLINE_HPP */