/*
* Copyright (c) 2004, 2011, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions 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 Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This source code is provided to illustrate the usage of a given feature
* or technique and has been deliberately simplified. Additional steps
* required for a production-quality application, such as security checks,
* input validation and proper error handling, might not be present in
* this sample code.
*/
/*
*/
import static java.lang.management.ManagementFactory.*;
import java.lang.management.ThreadMXBean;
import java.lang.management.ThreadInfo;
import java.lang.management.LockInfo;
import java.lang.management.MonitorInfo;
import javax.management.*;
import java.io.*;
/**
* Example of using the java.lang.management API to dump stack trace
* and to perform deadlock detection.
*
* @author Mandy Chung
*/
public 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 = ti.getLockedMonitors();
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);
printMonitorInfo(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;
}
}
}