001    /*
002     * Copyright 2011 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.kfs.sys;
017    
018    import java.lang.management.ManagementFactory;
019    import java.lang.management.MemoryNotificationInfo;
020    import java.lang.management.MemoryPoolMXBean;
021    import java.lang.management.MemoryType;
022    import java.util.ArrayList;
023    import java.util.Arrays;
024    import java.util.Collection;
025    import java.util.HashMap;
026    import java.util.Map;
027    
028    import javax.management.Notification;
029    import javax.management.NotificationEmitter;
030    import javax.management.NotificationListener;
031    
032    import org.apache.log4j.Logger;
033    
034    public class MemoryMonitor {
035        private final Collection<Listener> listeners = new ArrayList<Listener>();
036        private static final Logger LOG = Logger.getLogger(MemoryMonitor.class);
037        private String springContextId;
038    
039        public interface Listener {
040            public void memoryUsageLow(String springContextId, Map<String, String> memoryUsageStatistics, String deadlockedThreadIds);
041        }
042    
043        public MemoryMonitor() {
044            LOG.info("initializing");
045            this.springContextId = "Unknown";
046            ManagementFactory.getThreadMXBean().setThreadContentionMonitoringEnabled(true);
047            ManagementFactory.getThreadMXBean().setThreadCpuTimeEnabled(true);
048            ((NotificationEmitter) ManagementFactory.getMemoryMXBean()).addNotificationListener(new NotificationListener() {
049                public void handleNotification(Notification n, Object hb) {
050                    if (n.getType().equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED)) {
051                        Map<String, String> memoryUsageStatistics = new HashMap<String, String>();
052                        memoryUsageStatistics.put("MemoryMXBean: " + MemoryType.HEAP, ManagementFactory.getMemoryMXBean().getHeapMemoryUsage().toString());
053                        memoryUsageStatistics.put("MemoryMXBean:" + MemoryType.NON_HEAP, ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage().toString());
054                        for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {
055                            memoryUsageStatistics.put("MemoryPoolMXBean: " + pool.getType(), pool.getUsage().toString());
056                        }
057                        for (Listener listener : listeners) {
058                            listener.memoryUsageLow(springContextId, memoryUsageStatistics, Arrays.toString(ManagementFactory.getThreadMXBean().findMonitorDeadlockedThreads()));
059                        }
060                    }
061                }
062            }, null, null);
063        }
064    
065        public MemoryMonitor(String springContextId) {
066            this();
067            this.springContextId = springContextId;
068        }
069    
070        public boolean addListener(Listener listener) {
071            return listeners.add(listener);
072        }
073    
074        public boolean removeListener(Listener listener) {
075            return listeners.remove(listener);
076        }
077    
078        public static void setPercentageUsageThreshold(double percentage) {
079            for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {
080                if (pool.getType() == MemoryType.HEAP && pool.isUsageThresholdSupported()) {
081                    if (percentage <= 0.0 || percentage > 1.0) {
082                        throw new IllegalArgumentException("percentage not in range");
083                    }
084                    long warningThreshold = (long) (pool.getUsage().getMax() * percentage);
085                    pool.setUsageThreshold(warningThreshold);
086                }
087            }
088        }
089    }