Performing deadlock detection programmatically within the application using the java.lang.management API
/*
* @(#)Deadlock.java 1.5 05/11/17
*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
/*
* @(#)Deadlock.java 1.5 05/11/17
*/
import static java.lang.management.ManagementFactory.THREAD_MXBEAN_NAME;
import static java.lang.management.ManagementFactory.getThreadMXBean;
import static java.lang.management.ManagementFactory.newPlatformMXBeanProxy;
import java.io.IOException;
import java.lang.management.LockInfo;
import java.lang.management.MonitorInfo;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import javax.management.InstanceNotFoundException;
import javax.management.IntrospectionException;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanServerConnection;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.ReflectionException;
/**
* This Deadlock class demonstrates the capability of performing deadlock
* detection programmatically within the application using the
* java.lang.management API.
*
* See ThreadMonitor.java for the use of java.lang.management.ThreadMXBean API.
*/
public class Deadlock {
public static void main(String[] argv) {
Deadlock dl = new Deadlock();
// Now find deadlock
ThreadMonitor monitor = new ThreadMonitor();
boolean found = false;
while (!found) {
found = monitor.findDeadlock();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
System.exit(1);
}
}
System.out.println("\nPress <Enter> to exit this Deadlock program.\n");
waitForEnterPressed();
}
private CyclicBarrier barrier = new CyclicBarrier(6);
public Deadlock() {
DeadlockThread[] dThreads = new DeadlockThread[6];
Monitor a = new Monitor("a");
Monitor b = new Monitor("b");
Monitor c = new Monitor("c");
dThreads[0] = new DeadlockThread("MThread-1", a, b);
dThreads[1] = new DeadlockThread("MThread-2", b, c);
dThreads[2] = new DeadlockThread("MThread-3", c, a);
Lock d = new ReentrantLock();
Lock e = new ReentrantLock();
Lock f = new ReentrantLock();
dThreads[3] = new DeadlockThread("SThread-4", d, e);
dThreads[4] = new DeadlockThread("SThread-5", e, f);
dThreads[5] = new DeadlockThread("SThread-6", f, d);
// make them daemon threads so that the test will exit
for (int i = 0; i < 6; i++) {
dThreads[i].setDaemon(true);
dThreads[i].start();
}
}
class DeadlockThread extends Thread {
private Lock lock1 = null;
private Lock lock2 = null;
private Monitor mon1 = null;
private Monitor mon2 = null;
private boolean useSync;
DeadlockThread(String name, Lock lock1, Lock lock2) {
super(name);
this.lock1 = lock1;
this.lock2 = lock2;
this.useSync = true;
}
DeadlockThread(String name, Monitor mon1, Monitor mon2) {
super(name);
this.mon1 = mon1;
this.mon2 = mon2;
this.useSync = false;
}
public void run() {
if (useSync) {
syncLock();
} else {
monitorLock();
}
}
private void syncLock() {
lock1.lock();
try {
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
System.exit(1);
} catch (BrokenBarrierException e) {
e.printStackTrace();
System.exit(1);
}
goSyncDeadlock();
} finally {
lock1.unlock();
}
}
private void goSyncDeadlock() {
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
System.exit(1);
} catch (BrokenBarrierException e) {
e.printStackTrace();
System.exit(1);
}
lock2.lock();
throw new RuntimeException("should not reach here.");
}
private void monitorLock() {
synchronized (mon1) {
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
System.exit(1);
} catch (BrokenBarrierException e) {
e.printStackTrace();
System.exit(1);
}
goMonitorDeadlock();
}
}
private void goMonitorDeadlock() {
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
System.exit(1);
} catch (BrokenBarrierException e) {
e.printStackTrace();
System.exit(1);
}
synchronized (mon2) {
throw new RuntimeException(getName() + " should not reach here.");
}
}
}
class Monitor {
String name;
Monitor(String name) {
this.name = name;
}
}
private static void waitForEnterPressed() {
try {
boolean done = false;
while (!done) {
char ch = (char) System.in.read();
if (ch < 0 || ch == '\n') {
done = true;
}
}
} catch (IOException e) {
e.printStackTrace();
System.exit(0);
}
}
}
/*
* @(#)ThreadMonitor.java 1.6 05/12/22
*
* Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistribution of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS
* LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
* IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT
* OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR
* PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
* ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
* BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended for
* use in the design, construction, operation or maintenance of any nuclear
* facility.
*/
/*
* @(#)ThreadMonitor.java 1.6 05/12/22
*/
/**
* Example of using the java.lang.management API to dump stack trace and to
* perform deadlock detection.
*
* @author Mandy Chung
* @version %% 12/22/05
*/
class ThreadMonitor {
private MBeanServerConnection server;
private ThreadMXBean tmbean;
private ObjectName objname;
// default - JDK 6+ VM
private String findDeadlocksMethodName = "findDeadlockedThreads";
private boolean canDumpLocks = true;
/**
* Constructs a ThreadMonitor object to get thread information in a remote
* JVM.
*/
public ThreadMonitor(MBeanServerConnection server) throws IOException {
this.server = server;
this.tmbean = newPlatformMXBeanProxy(server, THREAD_MXBEAN_NAME, ThreadMXBean.class);
try {
objname = new ObjectName(THREAD_MXBEAN_NAME);
} catch (MalformedObjectNameException e) {
// should not reach here
InternalError ie = new InternalError(e.getMessage());
ie.initCause(e);
throw ie;
}
parseMBeanInfo();
}
/**
* Constructs a ThreadMonitor object to get thread information in the local
* JVM.
*/
public ThreadMonitor() {
this.tmbean = getThreadMXBean();
}
/**
* Prints the thread dump information to System.out.
*/
public void threadDump() {
if (canDumpLocks) {
if (tmbean.isObjectMonitorUsageSupported() && tmbean.isSynchronizerUsageSupported()) {
// Print lock info if both object monitor usage
// and synchronizer usage are supported.
// This sample code can be modified to handle if
// either monitor usage or synchronizer usage is supported.
dumpThreadInfoWithLocks();
}
} else {
dumpThreadInfo();
}
}
private void dumpThreadInfo() {
System.out.println("Full Java thread dump");
long[] tids = tmbean.getAllThreadIds();
ThreadInfo[] tinfos = tmbean.getThreadInfo(tids, Integer.MAX_VALUE);
for (ThreadInfo ti : tinfos) {
printThreadInfo(ti);
}
}
/**
* Prints the thread dump information with locks info to System.out.
*/
private void dumpThreadInfoWithLocks() {
System.out.println("Full Java thread dump with locks info");
ThreadInfo[] tinfos = tmbean.dumpAllThreads(true, true);
for (ThreadInfo ti : tinfos) {
printThreadInfo(ti);
LockInfo[] syncs = ti.getLockedSynchronizers();
printLockInfo(syncs);
}
System.out.println();
}
private static String INDENT = " ";
private void printThreadInfo(ThreadInfo ti) {
// print thread information
printThread(ti);
// print stack trace with locks
StackTraceElement[] stacktrace = ti.getStackTrace();
MonitorInfo[] monitors = ti.getLockedMonitors();
for (int i = 0; i < stacktrace.length; i++) {
StackTraceElement ste = stacktrace[i];
System.out.println(INDENT + "at " + ste.toString());
for (MonitorInfo mi : monitors) {
if (mi.getLockedStackDepth() == i) {
System.out.println(INDENT + " - locked " + mi);
}
}
}
System.out.println();
}
private void printThread(ThreadInfo ti) {
StringBuilder sb = new StringBuilder("\"" + ti.getThreadName() + "\"" + " Id="
+ ti.getThreadId() + " in " + ti.getThreadState());
if (ti.getLockName() != null) {
sb.append(" on lock=" + ti.getLockName());
}
if (ti.isSuspended()) {
sb.append(" (suspended)");
}
if (ti.isInNative()) {
sb.append(" (running in native)");
}
System.out.println(sb.toString());
if (ti.getLockOwnerName() != null) {
System.out.println(INDENT + " owned by " + ti.getLockOwnerName() + " Id="
+ ti.getLockOwnerId());
}
}
private void printMonitorInfo(ThreadInfo ti, MonitorInfo[] monitors) {
System.out.println(INDENT + "Locked monitors: count = " + monitors.length);
for (MonitorInfo mi : monitors) {
System.out.println(INDENT + " - " + mi + " locked at ");
System.out.println(INDENT + " " + mi.getLockedStackDepth() + " "
+ mi.getLockedStackFrame());
}
}
private void printLockInfo(LockInfo[] locks) {
System.out.println(INDENT + "Locked synchronizers: count = " + locks.length);
for (LockInfo li : locks) {
System.out.println(INDENT + " - " + li);
}
System.out.println();
}
/**
* Checks if any threads are deadlocked. If any, print the thread dump
* information.
*/
public boolean findDeadlock() {
long[] tids;
if (findDeadlocksMethodName.equals("findDeadlockedThreads")
&& tmbean.isSynchronizerUsageSupported()) {
tids = tmbean.findDeadlockedThreads();
if (tids == null) {
return false;
}
System.out.println("Deadlock found :-");
ThreadInfo[] infos = tmbean.getThreadInfo(tids, true, true);
for (ThreadInfo ti : infos) {
printThreadInfo(ti);
printLockInfo(ti.getLockedSynchronizers());
System.out.println();
}
} else {
tids = tmbean.findMonitorDeadlockedThreads();
if (tids == null) {
return false;
}
ThreadInfo[] infos = tmbean.getThreadInfo(tids, Integer.MAX_VALUE);
for (ThreadInfo ti : infos) {
// print thread information
printThreadInfo(ti);
}
}
return true;
}
private void parseMBeanInfo() throws IOException {
try {
MBeanOperationInfo[] mopis = server.getMBeanInfo(objname).getOperations();
// look for findDeadlockedThreads operations;
boolean found = false;
for (MBeanOperationInfo op : mopis) {
if (op.getName().equals(findDeadlocksMethodName)) {
found = true;
break;
}
}
if (!found) {
// if findDeadlockedThreads operation doesn't exist,
// the target VM is running on JDK 5 and details about
// synchronizers and locks cannot be dumped.
findDeadlocksMethodName = "findMonitorDeadlockedThreads";
canDumpLocks = false;
}
} catch (IntrospectionException e) {
InternalError ie = new InternalError(e.getMessage());
ie.initCause(e);
throw ie;
} catch (InstanceNotFoundException e) {
InternalError ie = new InternalError(e.getMessage());
ie.initCause(e);
throw ie;
} catch (ReflectionException e) {
InternalError ie = new InternalError(e.getMessage());
ie.initCause(e);
throw ie;
}
}
}
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