001 /**
002 * Copyright 2005-2012 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.kuali.rice.krad.util;
017
018 import java.lang.management.ManagementFactory;
019 import java.lang.management.MemoryMXBean;
020 import java.lang.management.MemoryNotificationInfo;
021 import java.lang.management.MemoryPoolMXBean;
022 import java.lang.management.MemoryType;
023 import java.util.ArrayList;
024 import java.util.Collection;
025
026 import javax.management.Notification;
027 import javax.management.NotificationEmitter;
028 import javax.management.NotificationListener;
029
030 import org.apache.log4j.Logger;
031
032 public class MemoryMonitor {
033 private final Collection<Listener> listeners = new ArrayList<Listener>();
034 private static final Logger LOG = Logger.getLogger(MemoryMonitor.class);
035 private String springContextId;
036
037 public interface Listener {
038 public void memoryUsageLow(String springContextId, long usedMemory, long maxMemory);
039 }
040
041 public MemoryMonitor() {
042 LOG.info("initializing");
043 this.springContextId = "Unknown";
044 MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
045 NotificationEmitter emitter = (NotificationEmitter) mbean;
046 emitter.addNotificationListener(new NotificationListener() {
047 public void handleNotification(Notification n, Object hb) {
048 if (n.getType().equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {
049 long maxMemory = tenuredGenPool.getUsage().getMax();
050 long usedMemory = tenuredGenPool.getUsage().getUsed();
051 for (Listener listener : listeners) {
052 listener.memoryUsageLow(springContextId, usedMemory, maxMemory);
053 }
054 }
055 }
056 }, null, null);
057 }
058
059 public MemoryMonitor(String springContextId) {
060 this();
061 this.springContextId = springContextId;
062 }
063
064 public boolean addListener(Listener listener) {
065 return listeners.add(listener);
066 }
067
068 public boolean removeListener(Listener listener) {
069 return listeners.remove(listener);
070 }
071
072 private static final MemoryPoolMXBean tenuredGenPool = findTenuredGenPool();
073
074 public static void setPercentageUsageThreshold(double percentage) {
075 if (percentage <= 0.0 || percentage > 1.0) {
076 throw new IllegalArgumentException("percentage not in range");
077 }
078 long maxMemory = tenuredGenPool.getUsage().getMax();
079 long warningThreshold = (long) (maxMemory * percentage);
080 tenuredGenPool.setUsageThreshold(warningThreshold);
081 }
082
083 private static MemoryPoolMXBean findTenuredGenPool() {
084 for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {
085 if (pool.getType() == MemoryType.HEAP && pool.isUsageThresholdSupported()) {
086 return pool;
087 }
088 }
089 throw new AssertionError("could not find tenured space");
090 }
091 }