Java tutorial
/* * @(#)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; } } }