bool DefNewGeneration::expand(size_t bytes) {
  MutexLocker x(ExpandHeap_lock);
  HeapWord* prev_high = (HeapWord*) _virtual_space.high();
  bool success = _virtual_space.expand_by(bytes);
  if (success && ZapUnusedHeapArea) {
    // Mangle newly committed space immediately because it
    // can be done here more simply that after the new
    // spaces have been computed.
    HeapWord* new_high = (HeapWord*) _virtual_space.high();
    MemRegion mangle_region(prev_high, new_high);
    SpaceMangler::mangle_region(mangle_region);
  }

  // Do not attempt an expand-to-the reserve size.  The
  // request should properly observe the maximum size of
  // the generation so an expand-to-reserve should be
  // unnecessary.  Also a second call to expand-to-reserve
  // value potentially can cause an undue expansion.
  // For example if the first expand fail for unknown reasons,
  // but the second succeeds and expands the heap to its maximum
  // value.
  if (GC_locker::is_active()) {
    if (PrintGC && Verbose) {
      gclog_or_tty->print_cr("Garbage collection disabled, "
        "expanded heap instead");
    }
  }

  return success;
}
bool CardGeneration::grow_by(size_t bytes) {
  assert_correct_size_change_locking();
  bool result = _virtual_space.expand_by(bytes);
  if (result) {
    size_t new_word_size =
       heap_word_size(_virtual_space.committed_size());
    MemRegion mr(space()->bottom(), new_word_size);
    // Expand card table
    GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr);
    // Expand shared block offset array
    _bts->resize(new_word_size);

    // Fix for bug #4668531
    if (ZapUnusedHeapArea) {
      MemRegion mangle_region(space()->end(),
      (HeapWord*)_virtual_space.high());
      SpaceMangler::mangle_region(mangle_region);
    }

    // Expand space -- also expands space's BOT
    // (which uses (part of) shared array above)
    space()->set_end((HeapWord*)_virtual_space.high());

    // update the space and generation capacity counters
    update_counters();

    size_t new_mem_size = _virtual_space.committed_size();
    size_t old_mem_size = new_mem_size - bytes;
    log_trace(gc, heap)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
                    name(), old_mem_size/K, bytes/K, new_mem_size/K);
  }
  return result;
}
Exemple #3
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Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
    _level(level),
    _ref_processor(NULL) {
    if (!_virtual_space.initialize(rs, initial_size)) {
        vm_exit_during_initialization("Could not reserve enough space for "
                                      "object heap");
    }
    // Mangle all of the the initial generation.
    if (ZapUnusedHeapArea) {
        MemRegion mangle_region((HeapWord*)_virtual_space.low(),
                                (HeapWord*)_virtual_space.high());
        SpaceMangler::mangle_region(mangle_region);
    }
    _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
                          (HeapWord*)_virtual_space.high_boundary());
}
Exemple #4
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bool OneContigSpaceCardGeneration::grow_by(size_t bytes) {
    assert_locked_or_safepoint(ExpandHeap_lock);
    bool result = _virtual_space.expand_by(bytes);
    if (result) {
        size_t new_word_size =
            heap_word_size(_virtual_space.committed_size());
        MemRegion mr(_the_space->bottom(), new_word_size);
        // Expand card table
        Universe::heap()->barrier_set()->resize_covered_region(mr);
        // Expand shared block offset array
        _bts->resize(new_word_size);

        // Fix for bug #4668531
        if (ZapUnusedHeapArea) {
            MemRegion mangle_region(_the_space->end(),
                                    (HeapWord*)_virtual_space.high());
            SpaceMangler::mangle_region(mangle_region);
        }

        // Expand space -- also expands space's BOT
        // (which uses (part of) shared array above)
        _the_space->set_end((HeapWord*)_virtual_space.high());

        // update the space and generation capacity counters
        update_counters();

        if (Verbose && PrintGC) {
            size_t new_mem_size = _virtual_space.committed_size();
            size_t old_mem_size = new_mem_size - bytes;
            gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
                                   SIZE_FORMAT "K to " SIZE_FORMAT "K",
                                   name(), old_mem_size/K, bytes/K, new_mem_size/K);
        }
    }
    return result;
}
// NOTE! We need to be careful about resizing. During a GC, multiple
// allocators may be active during heap expansion. If we allow the
// heap resizing to become visible before we have correctly resized
// all heap related data structures, we may cause program failures.
void PSOldGen::post_resize() {
  // First construct a memregion representing the new size
  MemRegion new_memregion((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
  size_t new_word_size = new_memregion.word_size();

  // Block offset table resize FIX ME!!!!!
  // _bts->resize(new_word_size);
  Universe::heap()->barrier_set()->resize_covered_region(new_memregion);

  // Did we expand?
  if (object_space()->end() < (HeapWord*) _virtual_space.high()) {
    // We need to mangle the newly expanded area. The memregion spans
    // end -> new_end, we assume that top -> end is already mangled.
    // This cannot be safely tested for, as allocation may be taking
    // place.
    MemRegion mangle_region(object_space()->end(),(HeapWord*) _virtual_space.high());
    object_space()->mangle_region(mangle_region); 
  }

  // ALWAYS do this last!!
  object_space()->set_end((HeapWord*) _virtual_space.high());

  assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()), "Sanity");
}
bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
  const size_t alignment = virtual_space()->alignment();
  size_t orig_size = virtual_space()->committed_size();
  bool size_changed = false;

  // There used to be this guarantee there.
  // guarantee ((eden_size + 2*survivor_size)  <= _max_gen_size, "incorrect input arguments");
  // Code below forces this requirement.  In addition the desired eden
  // size and disired survivor sizes are desired goals and may
  // exceed the total generation size.

  assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking");

  // Adjust new generation size
  const size_t eden_plus_survivors =
          align_size_up(eden_size + 2 * survivor_size, alignment);
  size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_size()),
                             min_gen_size());
  assert(desired_size <= max_size(), "just checking");

  if (desired_size > orig_size) {
    // Grow the generation
    size_t change = desired_size - orig_size;
    assert(change % alignment == 0, "just checking");
    HeapWord* prev_high = (HeapWord*) virtual_space()->high();
    if (!virtual_space()->expand_by(change)) {
      return false; // Error if we fail to resize!
    }
    if (ZapUnusedHeapArea) {
      // Mangle newly committed space immediately because it
      // can be done here more simply that after the new
      // spaces have been computed.
      HeapWord* new_high = (HeapWord*) virtual_space()->high();
      MemRegion mangle_region(prev_high, new_high);
      SpaceMangler::mangle_region(mangle_region);
    }
    size_changed = true;
  } else if (desired_size < orig_size) {
    size_t desired_change = orig_size - desired_size;
    assert(desired_change % alignment == 0, "just checking");

    desired_change = limit_gen_shrink(desired_change);

    if (desired_change > 0) {
      virtual_space()->shrink_by(desired_change);
      reset_survivors_after_shrink();

      size_changed = true;
    }
  } else {
    if (Verbose && PrintGC) {
      if (orig_size == gen_size_limit()) {
        gclog_or_tty->print_cr("PSYoung generation size at maximum: "
          SIZE_FORMAT "K", orig_size/K);
      } else if (orig_size == min_gen_size()) {
        gclog_or_tty->print_cr("PSYoung generation size at minium: "
          SIZE_FORMAT "K", orig_size/K);
      }
    }
  }

  if (size_changed) {
    post_resize();

    if (Verbose && PrintGC) {
      size_t current_size  = virtual_space()->committed_size();
      gclog_or_tty->print_cr("PSYoung generation size changed: "
                             SIZE_FORMAT "K->" SIZE_FORMAT "K",
                             orig_size/K, current_size/K);
    }
  }

  guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
            virtual_space()->committed_size() == max_size(), "Sanity");

  return true;
}
// Similar to PSYoungGen::resize_generation() but
//  allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
//  expands at the low end of the virtual space
//  moves the boundary between the generations in order to expand
//  some additional diagnostics
// If no additional changes are required, this can be deleted
// and the changes factored back into PSYoungGen::resize_generation().
bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
  const size_t alignment = virtual_space()->alignment();
  size_t orig_size = virtual_space()->committed_size();
  bool size_changed = false;

  // There used to be a guarantee here that
  //   (eden_size + 2*survivor_size)  <= _max_gen_size
  // This requirement is enforced by the calculation of desired_size
  // below.  It may not be true on entry since the size of the
  // eden_size is no bounded by the generation size.

  assert(max_size() == reserved().byte_size(), "max gen size problem?");
  assert(min_gen_size() <= orig_size && orig_size <= max_size(),
         "just checking");

  // Adjust new generation size
  const size_t eden_plus_survivors =
    align_size_up(eden_size + 2 * survivor_size, alignment);
  size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
                             min_gen_size());
  assert(desired_size <= gen_size_limit(), "just checking");

  if (desired_size > orig_size) {
    // Grow the generation
    size_t change = desired_size - orig_size;
    HeapWord* prev_low = (HeapWord*) virtual_space()->low();
    if (!virtual_space()->expand_by(change)) {
      return false;
    }
    if (ZapUnusedHeapArea) {
      // Mangle newly committed space immediately because it
      // can be done here more simply that after the new
      // spaces have been computed.
      HeapWord* new_low = (HeapWord*) virtual_space()->low();
      assert(new_low < prev_low, "Did not grow");

      MemRegion mangle_region(new_low, prev_low);
      SpaceMangler::mangle_region(mangle_region);
    }
    size_changed = true;
  } else if (desired_size < orig_size) {
    size_t desired_change = orig_size - desired_size;

    // How much is available for shrinking.
    size_t available_bytes = limit_gen_shrink(desired_change);
    size_t change = MIN2(desired_change, available_bytes);
    virtual_space()->shrink_by(change);
    size_changed = true;
  } else {
    if (Verbose && PrintGC) {
      if (orig_size == gen_size_limit()) {
        gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
          SIZE_FORMAT "K", orig_size/K);
      } else if (orig_size == min_gen_size()) {
        gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
          SIZE_FORMAT "K", orig_size/K);
      }
    }
  }

  if (size_changed) {
    reset_after_change();
    if (Verbose && PrintGC) {
      size_t current_size  = virtual_space()->committed_size();
      gclog_or_tty->print_cr("ASPSYoung generation size changed: "
        SIZE_FORMAT "K->" SIZE_FORMAT "K",
        orig_size/K, current_size/K);
    }
  }

  guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
            virtual_space()->committed_size() == max_size(), "Sanity");

  return true;
}
void ContiguousSpace::mangle_unused_area() {
  // to-space is used for storing marks during mark-sweep
  mangle_region(MemRegion(top(), end()));
}