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/*
* Derby - Class org.apache.derbyTesting.functionTests.util.Barrier
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied. See the License for the specific
* language governing permissions and limitations under the License.
*/
package org.apache.derbyTesting.functionTests.util;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanException;
import javax.management.MalformedObjectNameException;
import javax.management.ReflectionException;
/**
* A deadlock watch utlity. An instance of this class can be created and started
* and it will look for a Java level deadlock at the time given if not stopped.
* A deadlock is detected using JMX and the ThreadMXBean
*/
public class DeadlockWatchdog implements Runnable {
private boolean stopped = false;
private long timeout;
public DeadlockWatchdog(long timeout) {
this.timeout = timeout;
}
public synchronized void start() {
stopped = false;
Thread t = new Thread(this, "WATCHDOG");
t.setDaemon(true);
t.start();
}
public synchronized void stop() {
stopped = true;
notifyAll();
}
public synchronized void run() {
final long until = System.currentTimeMillis() + timeout;
long now;
while (!stopped && until > (now = System.currentTimeMillis())) {
try {
wait(until - now);
} catch (InterruptedException e) {
}
}
if (!stopped) {
try {
boolean res = AccessController.doPrivileged(
new PrivilegedExceptionAction<Boolean>() {
public Boolean run() throws IOException, MalformedObjectNameException, InstanceNotFoundException, MBeanException, ReflectionException {
return checkForDeadlock();
}
});
if (res) {
System.err.println("Deadlock detected");
System.exit(1);
}
} catch (Exception x) {
System.err.println("Watchdog failed: " + x.toString());
System.exit(1);
}
}
}
boolean checkForDeadlock() throws MalformedObjectNameException, InstanceNotFoundException, MBeanException, ReflectionException, IOException {
ThreadMXBean bean = ManagementFactory.getThreadMXBean();
long[] findDeadlockedThreads = bean.findDeadlockedThreads();
if (null != findDeadlockedThreads && 0 != findDeadlockedThreads.length) {
return true;
}
return false;
}
}
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