Java example source code file (ThreadInfo.java)

This example Java source code file (ThreadInfo.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

empty_monitors, empty_syncs, lockinfo, max_frames, monitorinfo, no_stack_trace, object, stacktraceelement, string, stringbuilder, threadinfo, threadinfocompositedata, timed_waiting

The ThreadInfo.java Java example source code

/*
 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.lang.management;

import javax.management.openmbean.CompositeData;
import sun.management.ManagementFactoryHelper;
import sun.management.ThreadInfoCompositeData;
import static java.lang.Thread.State.*;

/**
 * Thread information. <tt>ThreadInfo contains the information
 * about a thread including:
 * <h3>General thread information
 * <ul>
 *   <li>Thread ID.
 *   <li>Name of the thread.
 * </ul>
 *
 * <h3>Execution information
 * <ul>
 *   <li>Thread state.
 *   <li>The object upon which the thread is blocked due to:
 *       <ul>
 *       <li>waiting to enter a synchronization block/method, or
 *       <li>waiting to be notified in a {@link Object#wait Object.wait} method,
 *           or</li>
 *       <li>parking due to a {@link java.util.concurrent.locks.LockSupport#park
 *           LockSupport.park} call.</li>
 *       </ul>
 *   </li>
 *   <li>The ID of the thread that owns the object
 *       that the thread is blocked.</li>
 *   <li>Stack trace of the thread.
 *   <li>List of object monitors locked by the thread.
 *   <li>List of 
 *       ownable synchronizers</a> locked by the thread.
 * </ul>
 *
 * <h4>Synchronization Statistics
 * <ul>
 *   <li>The number of times that the thread has blocked for
 *       synchronization or waited for notification.</li>
 *   <li>The accumulated elapsed time that the thread has blocked
 *       for synchronization or waited for notification
 *       since {@link ThreadMXBean#setThreadContentionMonitoringEnabled
 *       thread contention monitoring}
 *       was enabled. Some Java virtual machine implementation
 *       may not support this.  The
 *       {@link ThreadMXBean#isThreadContentionMonitoringSupported()}
 *       method can be used to determine if a Java virtual machine
 *       supports this.</li>
 * </ul>
 *
 * <p>This thread information class is designed for use in monitoring of
 * the system, not for synchronization control.
 *
 * <h4>MXBean Mapping
 * <tt>ThreadInfo is mapped to a {@link CompositeData CompositeData}
 * with attributes as specified in
 * the {@link #from from} method.
 *
 * @see ThreadMXBean#getThreadInfo
 * @see ThreadMXBean#dumpAllThreads
 *
 * @author  Mandy Chung
 * @since   1.5
 */

public class ThreadInfo {
    private String       threadName;
    private long         threadId;
    private long         blockedTime;
    private long         blockedCount;
    private long         waitedTime;
    private long         waitedCount;
    private LockInfo     lock;
    private String       lockName;
    private long         lockOwnerId;
    private String       lockOwnerName;
    private boolean      inNative;
    private boolean      suspended;
    private Thread.State threadState;
    private StackTraceElement[] stackTrace;
    private MonitorInfo[]       lockedMonitors;
    private LockInfo[]          lockedSynchronizers;

    private static MonitorInfo[] EMPTY_MONITORS = new MonitorInfo[0];
    private static LockInfo[] EMPTY_SYNCS = new LockInfo[0];

    /**
     * Constructor of ThreadInfo created by the JVM
     *
     * @param t             Thread
     * @param state         Thread state
     * @param lockObj       Object on which the thread is blocked
     * @param lockOwner     the thread holding the lock
     * @param blockedCount  Number of times blocked to enter a lock
     * @param blockedTime   Approx time blocked to enter a lock
     * @param waitedCount   Number of times waited on a lock
     * @param waitedTime    Approx time waited on a lock
     * @param stackTrace    Thread stack trace
     */
    private ThreadInfo(Thread t, int state, Object lockObj, Thread lockOwner,
                       long blockedCount, long blockedTime,
                       long waitedCount, long waitedTime,
                       StackTraceElement[] stackTrace) {
        initialize(t, state, lockObj, lockOwner,
                   blockedCount, blockedTime,
                   waitedCount, waitedTime, stackTrace,
                   EMPTY_MONITORS, EMPTY_SYNCS);
    }

    /**
     * Constructor of ThreadInfo created by the JVM
     * for {@link ThreadMXBean#getThreadInfo(long[],boolean,boolean)}
     * and {@link ThreadMXBean#dumpAllThreads}
     *
     * @param t             Thread
     * @param state         Thread state
     * @param lockObj       Object on which the thread is blocked
     * @param lockOwner     the thread holding the lock
     * @param blockedCount  Number of times blocked to enter a lock
     * @param blockedTime   Approx time blocked to enter a lock
     * @param waitedCount   Number of times waited on a lock
     * @param waitedTime    Approx time waited on a lock
     * @param stackTrace    Thread stack trace
     * @param monitors      List of locked monitors
     * @param stackDepths   List of stack depths
     * @param synchronizers List of locked synchronizers
     */
    private ThreadInfo(Thread t, int state, Object lockObj, Thread lockOwner,
                       long blockedCount, long blockedTime,
                       long waitedCount, long waitedTime,
                       StackTraceElement[] stackTrace,
                       Object[] monitors,
                       int[] stackDepths,
                       Object[] synchronizers) {
        int numMonitors = (monitors == null ? 0 : monitors.length);
        MonitorInfo[] lockedMonitors;
        if (numMonitors == 0) {
            lockedMonitors = EMPTY_MONITORS;
        } else {
            lockedMonitors = new MonitorInfo[numMonitors];
            for (int i = 0; i < numMonitors; i++) {
                Object lock = monitors[i];
                String className = lock.getClass().getName();
                int identityHashCode = System.identityHashCode(lock);
                int depth = stackDepths[i];
                StackTraceElement ste = (depth >= 0 ? stackTrace[depth]
                                                    : null);
                lockedMonitors[i] = new MonitorInfo(className,
                                                    identityHashCode,
                                                    depth,
                                                    ste);
            }
        }

        int numSyncs = (synchronizers == null ? 0 : synchronizers.length);
        LockInfo[] lockedSynchronizers;
        if (numSyncs == 0) {
            lockedSynchronizers = EMPTY_SYNCS;
        } else {
            lockedSynchronizers = new LockInfo[numSyncs];
            for (int i = 0; i < numSyncs; i++) {
                Object lock = synchronizers[i];
                String className = lock.getClass().getName();
                int identityHashCode = System.identityHashCode(lock);
                lockedSynchronizers[i] = new LockInfo(className,
                                                      identityHashCode);
            }
        }

        initialize(t, state, lockObj, lockOwner,
                   blockedCount, blockedTime,
                   waitedCount, waitedTime, stackTrace,
                   lockedMonitors, lockedSynchronizers);
    }

    /**
     * Initialize ThreadInfo object
     *
     * @param t             Thread
     * @param state         Thread state
     * @param lockObj       Object on which the thread is blocked
     * @param lockOwner     the thread holding the lock
     * @param blockedCount  Number of times blocked to enter a lock
     * @param blockedTime   Approx time blocked to enter a lock
     * @param waitedCount   Number of times waited on a lock
     * @param waitedTime    Approx time waited on a lock
     * @param stackTrace    Thread stack trace
     * @param lockedMonitors List of locked monitors
     * @param lockedSynchronizers List of locked synchronizers
     */
    private void initialize(Thread t, int state, Object lockObj, Thread lockOwner,
                            long blockedCount, long blockedTime,
                            long waitedCount, long waitedTime,
                            StackTraceElement[] stackTrace,
                            MonitorInfo[] lockedMonitors,
                            LockInfo[] lockedSynchronizers) {
        this.threadId = t.getId();
        this.threadName = t.getName();
        this.threadState = ManagementFactoryHelper.toThreadState(state);
        this.suspended = ManagementFactoryHelper.isThreadSuspended(state);
        this.inNative = ManagementFactoryHelper.isThreadRunningNative(state);
        this.blockedCount = blockedCount;
        this.blockedTime = blockedTime;
        this.waitedCount = waitedCount;
        this.waitedTime = waitedTime;

        if (lockObj == null) {
            this.lock = null;
            this.lockName = null;
        } else {
            this.lock = new LockInfo(lockObj);
            this.lockName =
                lock.getClassName() + '@' +
                    Integer.toHexString(lock.getIdentityHashCode());
        }
        if (lockOwner == null) {
            this.lockOwnerId = -1;
            this.lockOwnerName = null;
        } else {
            this.lockOwnerId = lockOwner.getId();
            this.lockOwnerName = lockOwner.getName();
        }
        if (stackTrace == null) {
            this.stackTrace = NO_STACK_TRACE;
        } else {
            this.stackTrace = stackTrace;
        }
        this.lockedMonitors = lockedMonitors;
        this.lockedSynchronizers = lockedSynchronizers;
    }

    /*
     * Constructs a <tt>ThreadInfo object from a
     * {@link CompositeData CompositeData}.
     */
    private ThreadInfo(CompositeData cd) {
        ThreadInfoCompositeData ticd = ThreadInfoCompositeData.getInstance(cd);

        threadId = ticd.threadId();
        threadName = ticd.threadName();
        blockedTime = ticd.blockedTime();
        blockedCount = ticd.blockedCount();
        waitedTime = ticd.waitedTime();
        waitedCount = ticd.waitedCount();
        lockName = ticd.lockName();
        lockOwnerId = ticd.lockOwnerId();
        lockOwnerName = ticd.lockOwnerName();
        threadState = ticd.threadState();
        suspended = ticd.suspended();
        inNative = ticd.inNative();
        stackTrace = ticd.stackTrace();

        // 6.0 attributes
        if (ticd.isCurrentVersion()) {
            lock = ticd.lockInfo();
            lockedMonitors = ticd.lockedMonitors();
            lockedSynchronizers = ticd.lockedSynchronizers();
        } else {
            // lockInfo is a new attribute added in 1.6 ThreadInfo
            // If cd is a 5.0 version, construct the LockInfo object
            //  from the lockName value.
            if (lockName != null) {
                String result[] = lockName.split("@");
                if (result.length == 2) {
                    int identityHashCode = Integer.parseInt(result[1], 16);
                    lock = new LockInfo(result[0], identityHashCode);
                } else {
                    assert result.length == 2;
                    lock = null;
                }
            } else {
                lock = null;
            }
            lockedMonitors = EMPTY_MONITORS;
            lockedSynchronizers = EMPTY_SYNCS;
        }
    }

    /**
     * Returns the ID of the thread associated with this <tt>ThreadInfo.
     *
     * @return the ID of the associated thread.
     */
    public long getThreadId() {
        return threadId;
    }

    /**
     * Returns the name of the thread associated with this <tt>ThreadInfo.
     *
     * @return the name of the associated thread.
     */
    public String getThreadName() {
        return threadName;
    }

    /**
     * Returns the state of the thread associated with this <tt>ThreadInfo.
     *
     * @return <tt>Thread.State of the associated thread.
     */
    public Thread.State getThreadState() {
         return threadState;
    }

    /**
     * Returns the approximate accumulated elapsed time (in milliseconds)
     * that the thread associated with this <tt>ThreadInfo
     * has blocked to enter or reenter a monitor
     * since thread contention monitoring is enabled.
     * I.e. the total accumulated time the thread has been in the
     * {@link java.lang.Thread.State#BLOCKED BLOCKED} state since thread
     * contention monitoring was last enabled.
     * This method returns <tt>-1 if thread contention monitoring
     * is disabled.
     *
     * <p>The Java virtual machine may measure the time with a high
     * resolution timer.  This statistic is reset when
     * the thread contention monitoring is reenabled.
     *
     * @return the approximate accumulated elapsed time in milliseconds
     * that a thread entered the <tt>BLOCKED state;
     * <tt>-1 if thread contention monitoring is disabled.
     *
     * @throws java.lang.UnsupportedOperationException if the Java
     * virtual machine does not support this operation.
     *
     * @see ThreadMXBean#isThreadContentionMonitoringSupported
     * @see ThreadMXBean#setThreadContentionMonitoringEnabled
     */
    public long getBlockedTime() {
        return blockedTime;
    }

    /**
     * Returns the total number of times that
     * the thread associated with this <tt>ThreadInfo
     * blocked to enter or reenter a monitor.
     * I.e. the number of times a thread has been in the
     * {@link java.lang.Thread.State#BLOCKED BLOCKED} state.
     *
     * @return the total number of times that the thread
     * entered the <tt>BLOCKED state.
     */
    public long getBlockedCount() {
        return blockedCount;
    }

    /**
     * Returns the approximate accumulated elapsed time (in milliseconds)
     * that the thread associated with this <tt>ThreadInfo
     * has waited for notification
     * since thread contention monitoring is enabled.
     * I.e. the total accumulated time the thread has been in the
     * {@link java.lang.Thread.State#WAITING WAITING}
     * or {@link java.lang.Thread.State#TIMED_WAITING TIMED_WAITING} state
     * since thread contention monitoring is enabled.
     * This method returns <tt>-1 if thread contention monitoring
     * is disabled.
     *
     * <p>The Java virtual machine may measure the time with a high
     * resolution timer.  This statistic is reset when
     * the thread contention monitoring is reenabled.
     *
     * @return the approximate accumulated elapsed time in milliseconds
     * that a thread has been in the <tt>WAITING or
     * <tt>TIMED_WAITING state;
     * <tt>-1 if thread contention monitoring is disabled.
     *
     * @throws java.lang.UnsupportedOperationException if the Java
     * virtual machine does not support this operation.
     *
     * @see ThreadMXBean#isThreadContentionMonitoringSupported
     * @see ThreadMXBean#setThreadContentionMonitoringEnabled
     */
    public long getWaitedTime() {
        return waitedTime;
    }

    /**
     * Returns the total number of times that
     * the thread associated with this <tt>ThreadInfo
     * waited for notification.
     * I.e. the number of times that a thread has been
     * in the {@link java.lang.Thread.State#WAITING WAITING}
     * or {@link java.lang.Thread.State#TIMED_WAITING TIMED_WAITING} state.
     *
     * @return the total number of times that the thread
     * was in the <tt>WAITING or TIMED_WAITING state.
     */
    public long getWaitedCount() {
        return waitedCount;
    }

    /**
     * Returns the <tt>LockInfo of an object for which
     * the thread associated with this <tt>ThreadInfo
     * is blocked waiting.
     * A thread can be blocked waiting for one of the following:
     * <ul>
     * <li>an object monitor to be acquired for entering or reentering
     *     a synchronization block/method.
     *     <br>The thread is in the {@link java.lang.Thread.State#BLOCKED BLOCKED}
     *     state waiting to enter the <tt>synchronized statement
     *     or method.
     *     <p>
     * <li>an object monitor to be notified by another thread.
     *     <br>The thread is in the {@link java.lang.Thread.State#WAITING WAITING}
     *     or {@link java.lang.Thread.State#TIMED_WAITING TIMED_WAITING} state
     *     due to a call to the {@link Object#wait Object.wait} method.
     *     <p>
     * <li>a synchronization object responsible for the thread parking.
     *     <br>The thread is in the {@link java.lang.Thread.State#WAITING WAITING}
     *     or {@link java.lang.Thread.State#TIMED_WAITING TIMED_WAITING} state
     *     due to a call to the
     *     {@link java.util.concurrent.locks.LockSupport#park(Object)
     *     LockSupport.park} method.  The synchronization object
     *     is the object returned from
     *     {@link java.util.concurrent.locks.LockSupport#getBlocker
     *     LockSupport.getBlocker} method. Typically it is an
     *     <a href="LockInfo.html#OwnableSynchronizer"> ownable synchronizer
     *     or a {@link java.util.concurrent.locks.Condition Condition}.</li>
     * </ul>
     *
     * <p>This method returns null if the thread is not in any of
     * the above conditions.
     *
     * @return <tt>LockInfo of an object for which the thread
     *         is blocked waiting if any; <tt>null otherwise.
     * @since 1.6
     */
    public LockInfo getLockInfo() {
        return lock;
    }

    /**
     * Returns the {@link LockInfo#toString string representation}
     * of an object for which the thread associated with this
     * <tt>ThreadInfo is blocked waiting.
     * This method is equivalent to calling:
     * <blockquote>
     * <pre>
     * getLockInfo().toString()
     * </pre>
     *
     * <p>This method will return null if this thread is not blocked
     * waiting for any object or if the object is not owned by any thread.
     *
     * @return the string representation of the object on which
     * the thread is blocked if any;
     * <tt>null otherwise.
     *
     * @see #getLockInfo
     */
    public String getLockName() {
        return lockName;
    }

    /**
     * Returns the ID of the thread which owns the object
     * for which the thread associated with this <tt>ThreadInfo
     * is blocked waiting.
     * This method will return <tt>-1 if this thread is not blocked
     * waiting for any object or if the object is not owned by any thread.
     *
     * @return the thread ID of the owner thread of the object
     * this thread is blocked on;
     * <tt>-1 if this thread is not blocked
     * or if the object is not owned by any thread.
     *
     * @see #getLockInfo
     */
    public long getLockOwnerId() {
        return lockOwnerId;
    }

    /**
     * Returns the name of the thread which owns the object
     * for which the thread associated with this <tt>ThreadInfo
     * is blocked waiting.
     * This method will return <tt>null if this thread is not blocked
     * waiting for any object or if the object is not owned by any thread.
     *
     * @return the name of the thread that owns the object
     * this thread is blocked on;
     * <tt>null if this thread is not blocked
     * or if the object is not owned by any thread.
     *
     * @see #getLockInfo
     */
    public String getLockOwnerName() {
        return lockOwnerName;
    }

    /**
     * Returns the stack trace of the thread
     * associated with this <tt>ThreadInfo.
     * If no stack trace was requested for this thread info, this method
     * will return a zero-length array.
     * If the returned array is of non-zero length then the first element of
     * the array represents the top of the stack, which is the most recent
     * method invocation in the sequence.  The last element of the array
     * represents the bottom of the stack, which is the least recent method
     * invocation in the sequence.
     *
     * <p>Some Java virtual machines may, under some circumstances, omit one
     * or more stack frames from the stack trace.  In the extreme case,
     * a virtual machine that has no stack trace information concerning
     * the thread associated with this <tt>ThreadInfo
     * is permitted to return a zero-length array from this method.
     *
     * @return an array of <tt>StackTraceElement objects of the thread.
     */
    public StackTraceElement[] getStackTrace() {
        return stackTrace;
    }

    /**
     * Tests if the thread associated with this <tt>ThreadInfo
     * is suspended.  This method returns <tt>true if
     * {@link Thread#suspend} has been called.
     *
     * @return <tt>true if the thread is suspended;
     *         <tt>false otherwise.
     */
    public boolean isSuspended() {
         return suspended;
    }

    /**
     * Tests if the thread associated with this <tt>ThreadInfo
     * is executing native code via the Java Native Interface (JNI).
     * The JNI native code does not include
     * the virtual machine support code or the compiled native
     * code generated by the virtual machine.
     *
     * @return <tt>true if the thread is executing native code;
     *         <tt>false otherwise.
     */
    public boolean isInNative() {
         return inNative;
    }

    /**
     * Returns a string representation of this thread info.
     * The format of this string depends on the implementation.
     * The returned string will typically include
     * the {@linkplain #getThreadName thread name},
     * the {@linkplain #getThreadId thread ID},
     * its {@linkplain #getThreadState state},
     * and a {@linkplain #getStackTrace stack trace} if any.
     *
     * @return a string representation of this thread info.
     */
    public String toString() {
        StringBuilder sb = new StringBuilder("\"" + getThreadName() + "\"" +
                                             " Id=" + getThreadId() + " " +
                                             getThreadState());
        if (getLockName() != null) {
            sb.append(" on " + getLockName());
        }
        if (getLockOwnerName() != null) {
            sb.append(" owned by \"" + getLockOwnerName() +
                      "\" Id=" + getLockOwnerId());
        }
        if (isSuspended()) {
            sb.append(" (suspended)");
        }
        if (isInNative()) {
            sb.append(" (in native)");
        }
        sb.append('\n');
        int i = 0;
        for (; i < stackTrace.length && i < MAX_FRAMES; i++) {
            StackTraceElement ste = stackTrace[i];
            sb.append("\tat " + ste.toString());
            sb.append('\n');
            if (i == 0 && getLockInfo() != null) {
                Thread.State ts = getThreadState();
                switch (ts) {
                    case BLOCKED:
                        sb.append("\t-  blocked on " + getLockInfo());
                        sb.append('\n');
                        break;
                    case WAITING:
                        sb.append("\t-  waiting on " + getLockInfo());
                        sb.append('\n');
                        break;
                    case TIMED_WAITING:
                        sb.append("\t-  waiting on " + getLockInfo());
                        sb.append('\n');
                        break;
                    default:
                }
            }

            for (MonitorInfo mi : lockedMonitors) {
                if (mi.getLockedStackDepth() == i) {
                    sb.append("\t-  locked " + mi);
                    sb.append('\n');
                }
            }
       }
       if (i < stackTrace.length) {
           sb.append("\t...");
           sb.append('\n');
       }

       LockInfo[] locks = getLockedSynchronizers();
       if (locks.length > 0) {
           sb.append("\n\tNumber of locked synchronizers = " + locks.length);
           sb.append('\n');
           for (LockInfo li : locks) {
               sb.append("\t- " + li);
               sb.append('\n');
           }
       }
       sb.append('\n');
       return sb.toString();
    }
    private static final int MAX_FRAMES = 8;

    /**
     * Returns a <tt>ThreadInfo object represented by the
     * given <tt>CompositeData.
     * The given <tt>CompositeData must contain the following attributes
     * unless otherwise specified below:
     * <blockquote>
     * <table border summary="The attributes and their types the given CompositeData contains">
     * <tr>
     *   <th align=left>Attribute Name
     *   <th align=left>Type
     * </tr>
     * <tr>
     *   <td>threadId