This FullThreadDump class demonstrates the capability to get a full thread dump and also detect deadlock remotely.
/*
* @(#)FullThreadDump.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.
*/
/*
* @(#)FullThreadDump.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.net.MalformedURLException;
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;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;
/**
* This FullThreadDump class demonstrates the capability to get a full thread
* dump and also detect deadlock remotely.
*/
public class FullThreadDump {
private MBeanServerConnection server;
private JMXConnector jmxc;
public FullThreadDump(String hostname, int port) {
System.out.println("Connecting to " + hostname + ":" + port);
// Create an RMI connector client and connect it to
// the RMI connector server
String urlPath = "/jndi/rmi://" + hostname + ":" + port + "/jmxrmi";
connect(urlPath);
}
public void dump() {
try {
ThreadMonitor monitor = new ThreadMonitor(server);
monitor.threadDump();
if (!monitor.findDeadlock()) {
System.out.println("No deadlock found.");
}
} catch (IOException e) {
System.err.println("\nCommunication error: " + e.getMessage());
System.exit(1);
}
}
/**
* Connect to a JMX agent of a given URL.
*/
private void connect(String urlPath) {
try {
JMXServiceURL url = new JMXServiceURL("rmi", "", 0, urlPath);
this.jmxc = JMXConnectorFactory.connect(url);
this.server = jmxc.getMBeanServerConnection();
} catch (MalformedURLException e) {
// should not reach here
} catch (IOException e) {
System.err.println("\nCommunication error: " + e.getMessage());
System.exit(1);
}
}
public static void main(String[] args) {
if (args.length != 1) {
usage();
}
String[] arg2 = args[0].split(":");
if (arg2.length != 2) {
usage();
}
String hostname = arg2[0];
int port = -1;
try {
port = Integer.parseInt(arg2[1]);
} catch (NumberFormatException x) {
usage();
}
if (port < 0) {
usage();
}
// get full thread dump and perform deadlock detection
FullThreadDump ftd = new FullThreadDump(hostname, port);
ftd.dump();
}
private static void usage() {
System.out.println("Usage: java FullThreadDump <hostname>:<port>");
}
}
/*
* @(#)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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