src/hotspot/share/gc/shared/referencePolicy.cpp - master - githubmirror/panama-vector

src/hotspot/share/gc/shared/referencePolicy.cpp
67 строк3 KB
Axel Boldt-Christmas
8383186: Large SoftRefLRUPolicyMSPerMB can lead to overflow
22 май 2026, 17:11
22 май 2026, 17:1120c590f
/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
 *
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#include "classfile/javaClasses.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/gc_globals.hpp"
#include "gc/shared/referencePolicy.hpp"
#include "memory/universe.hpp"
#include "runtime/globals.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/integerCast.hpp"

void AbstractLRUReferencePolicy::set_max_interval(uint64_t max_interval) {
  assert(max_interval <= MaximumMaxInterval, "Sanity check");
  _max_interval = max_interval;
}

// The oop passed in is the SoftReference object, and not
// the object the SoftReference points to.
bool AbstractLRUReferencePolicy::should_clear_reference(oop p, jlong timestamp_clock) {
  assert(_max_interval <= MaximumMaxInterval, "Forgot to call setup");
  const uint64_t interval = integer_cast<uint64_t>(java_subtract(timestamp_clock, java_lang_ref_SoftReference::timestamp(p)));

  // The interval will be zero if the ref was accessed since the last scavenge/gc.
  if(interval <= _max_interval) {
    return false;
  }

  return true;
}

// Capture state (of-the-VM) information needed to evaluate the policy
void LRUCurrentHeapPolicy::setup() {
  // How much of the current heap was not used at the last gc
  const uint64_t current_heap = Universe::heap()->free_at_last_gc() / M;

  set_max_interval(current_heap * integer_cast<uint64_t>(SoftRefLRUPolicyMSPerMB));
}

// Capture state (of-the-VM) information needed to evaluate the policy
void LRUMaxHeapPolicy::setup() {
  // How much of the max heap was not used at the last gc
  const uint64_t max_heap = (MaxHeapSize - Universe::heap()->used_at_last_gc()) / M;

  set_max_interval(max_heap * integer_cast<uint64_t>(SoftRefLRUPolicyMSPerMB));
}