Java example source code file (asPSOldGen.cpp)

This example Java source code file (asPSOldGen.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

aspsoldgen::aspsoldgen, aspsoldgen\:\:available_for_contraction, aspsoldgen\:\:available_for_expansion, aspsoldgen\:\:reset_after_change, consistency, heapword\*, max2, memregion, parallelscavengeheap, parallelscavengeheap\*, psadaptivesizepolicy, psoldgen

The asPSOldGen.cpp Java example source code

/*
 * Copyright (c) 2003, 2013, 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.
 *
 */

#include "precompiled.hpp"
#include "gc_implementation/parallelScavenge/asPSOldGen.hpp"
#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
#include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
#include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
#include "memory/cardTableModRefBS.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/java.hpp"

// Whereas PSOldGen takes the maximum size of the generation
// (which doesn't change in the case of PSOldGen) as a parameter,
// ASPSOldGen takes the upper limit on the size of
// the generation as a parameter.  In ASPSOldGen the
// maximum size of the generation can change as the boundary
// moves.  The "maximum size of the generation" is still a valid
// concept since the generation can grow and shrink within that
// maximum.  There are lots of useful checks that use that
// maximum.  In PSOldGen the method max_gen_size() returns
// _max_gen_size (as set by the PSOldGen constructor).  This
// is how it always worked.  In ASPSOldGen max_gen_size()
// returned the size of the reserved space for the generation.
// That can change as the boundary moves.  Below the limit of
// the size of the generation is passed to the PSOldGen constructor
// for "_max_gen_size" (have to pass something) but it is not used later.
//
ASPSOldGen::ASPSOldGen(size_t initial_size,
                       size_t min_size,
                       size_t size_limit,
                       const char* gen_name,
                       int level) :
  PSOldGen(initial_size, min_size, size_limit, gen_name, level),
  _gen_size_limit(size_limit)
{}

ASPSOldGen::ASPSOldGen(PSVirtualSpace* vs,
                       size_t initial_size,
                       size_t min_size,
                       size_t size_limit,
                       const char* gen_name,
                       int level) :
  PSOldGen(initial_size, min_size, size_limit, gen_name, level),
  _gen_size_limit(size_limit)
{
  _virtual_space = vs;
}

void ASPSOldGen::initialize_work(const char* perf_data_name, int level) {
  PSOldGen::initialize_work(perf_data_name, level);

  // The old gen can grow to gen_size_limit().  _reserve reflects only
  // the current maximum that can be committed.
  assert(_reserved.byte_size() <= gen_size_limit(), "Consistency check");

  initialize_performance_counters(perf_data_name, level);
}

void ASPSOldGen::reset_after_change() {
  _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
                        (HeapWord*)virtual_space()->high_boundary());
  post_resize();
}


size_t ASPSOldGen::available_for_expansion() {
  assert(virtual_space()->is_aligned(gen_size_limit()), "not aligned");
  assert(gen_size_limit() >= virtual_space()->committed_size(), "bad gen size");

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  size_t result =  gen_size_limit() - virtual_space()->committed_size();
  size_t result_aligned = align_size_down(result, heap->generation_alignment());
  return result_aligned;
}

size_t ASPSOldGen::available_for_contraction() {
  size_t uncommitted_bytes = virtual_space()->uncommitted_size();
  if (uncommitted_bytes != 0) {
    return uncommitted_bytes;
  }

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  const size_t gen_alignment = heap->generation_alignment();
  PSAdaptiveSizePolicy* policy = heap->size_policy();
  const size_t working_size =
    used_in_bytes() + (size_t) policy->avg_promoted()->padded_average();
  const size_t working_aligned = align_size_up(working_size, gen_alignment);
  const size_t working_or_min = MAX2(working_aligned, min_gen_size());
  if (working_or_min > reserved().byte_size()) {
    // If the used or minimum gen size (aligned up) is greater
    // than the total reserved size, then the space available
    // for contraction should (after proper alignment) be 0
    return 0;
  }
  const size_t max_contraction =
    reserved().byte_size() - working_or_min;

  // Use the "increment" fraction instead of the "decrement" fraction
  // to allow the other gen to expand more aggressively.  The
  // "decrement" fraction is conservative because its intent is to
  // only reduce the footprint.

  size_t result = policy->promo_increment_aligned_down(max_contraction);
  // Also adjust for inter-generational alignment
  size_t result_aligned = align_size_down(result, gen_alignment);
  if (PrintAdaptiveSizePolicy && Verbose) {
    gclog_or_tty->print_cr("\nASPSOldGen::available_for_contraction:"
      " %d K / 0x%x", result_aligned/K, result_aligned);
    gclog_or_tty->print_cr(" reserved().byte_size() %d K / 0x%x ",
      reserved().byte_size()/K, reserved().byte_size());
    size_t working_promoted = (size_t) policy->avg_promoted()->padded_average();
    gclog_or_tty->print_cr(" padded promoted %d K / 0x%x",
      working_promoted/K, working_promoted);
    gclog_or_tty->print_cr(" used %d K / 0x%x",
      used_in_bytes()/K, used_in_bytes());
    gclog_or_tty->print_cr(" min_gen_size() %d K / 0x%x",
      min_gen_size()/K, min_gen_size());
    gclog_or_tty->print_cr(" max_contraction %d K / 0x%x",
      max_contraction/K, max_contraction);
    gclog_or_tty->print_cr("    without alignment %d K / 0x%x",
      policy->promo_increment(max_contraction)/K,
      policy->promo_increment(max_contraction));
    gclog_or_tty->print_cr(" alignment 0x%x", gen_alignment);
  }
  assert(result_aligned <= max_contraction, "arithmetic is wrong");
  return result_aligned;
}