https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
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 *
 * 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
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 *
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package java.lang.management;

import java.util.Map;


The management interface for the thread system of
the Java virtual machine.

 A Java virtual machine has a single instance of the implementation
class of this interface.  This instance implementing this interface is
an MXBean that can be obtained by calling the ManagementFactory.getThreadMXBean method or from the 
platform MBeanServer method. 
The ObjectName for uniquely identifying the MXBean for the thread system within an MBeanServer is: 
 
          java.lang:type=Threading 
 It can be obtained by calling the PlatformManagedObject.getObjectName method. 
Thread ID
 Thread ID is a positive long value returned by calling the Thread.getId method for a thread. The thread ID is unique during its lifetime. When a thread is terminated, this thread ID may be reused. 
 Some methods in this interface take a thread ID or an array
of thread IDs as the input parameter and return per-thread information.

Thread CPU time

A Java virtual machine implementation may support measuring
the CPU time for the current thread, for any thread, or for no threads.

 The isThreadCpuTimeSupported method can be used to determine if a Java virtual machine supports measuring of the CPU time for any thread. The isCurrentThreadCpuTimeSupported method can be used to determine if a Java virtual machine supports measuring of the CPU time for the current thread. A Java virtual machine implementation that supports CPU time measurement for any thread will also support that for the current thread. 
 The CPU time provided by this interface has nanosecond precision
but not necessarily nanosecond accuracy.

 A Java virtual machine may disable CPU time measurement by default. The isThreadCpuTimeEnabled and setThreadCpuTimeEnabled methods can be used to test if CPU time measurement is enabled and to enable/disable this support respectively. Enabling thread CPU measurement could be expensive in some Java virtual machine implementations. 
Thread Contention Monitoring

Some Java virtual machines may support thread contention monitoring.
When thread contention monitoring is enabled, the accumulated elapsed
time that the thread has blocked for synchronization or waited for
notification will be collected and returned in the
ThreadInfo object.

 The isThreadContentionMonitoringSupported method can be used to determine if a Java virtual machine supports thread contention monitoring. The thread contention monitoring is disabled by default. The setThreadContentionMonitoringEnabled method can be used to enable thread contention monitoring. 
Synchronization Information and Deadlock Detection
 Some Java virtual machines may support monitoring of object monitor usage and ownable synchronizer usage. The getThreadInfo(long[], boolean, boolean) and dumpAllThreads methods can be used to obtain the thread stack trace and synchronization information including which lock a thread is blocked to acquire or waiting on and which locks the thread currently owns. 
 The ThreadMXBean interface provides the findMonitorDeadlockedThreads and findDeadlockedThreads methods to find deadlocks in the running application. 
Author: Mandy Chung
See Also:
Since:  1.5
/**
 * The management interface for the thread system of
 * the Java virtual machine.
 *
 * <p> A Java virtual machine has a single instance of the implementation
 * class of this interface.  This instance implementing this interface is
 * an <a href="ManagementFactory.html#MXBean">MXBean</a>
 * that can be obtained by calling
 * the {@link ManagementFactory#getThreadMXBean} method or
 * from the {@link ManagementFactory#getPlatformMBeanServer
 * platform MBeanServer} method.
 *
 * <p>The {@code ObjectName} for uniquely identifying the MXBean for
 * the thread system within an MBeanServer is:
 * <blockquote>
 *    {@link ManagementFactory#THREAD_MXBEAN_NAME
 *           java.lang:type=Threading}
 * </blockquote>
 *
 * It can be obtained by calling the
 * {@link PlatformManagedObject#getObjectName} method.
 *
 * <h3>Thread ID</h3>
 * Thread ID is a positive long value returned by calling the
 * {@link java.lang.Thread#getId} method for a thread.
 * The thread ID is unique during its lifetime.  When a thread
 * is terminated, this thread ID may be reused.
 *
 * <p> Some methods in this interface take a thread ID or an array
 * of thread IDs as the input parameter and return per-thread information.
 *
 * <h3>Thread CPU time</h3>
 * A Java virtual machine implementation may support measuring
 * the CPU time for the current thread, for any thread, or for no threads.
 *
 * <p>
 * The {@link #isThreadCpuTimeSupported} method can be used to determine
 * if a Java virtual machine supports measuring of the CPU time for any
 * thread.  The {@link #isCurrentThreadCpuTimeSupported} method can
 * be used to determine if a Java virtual machine supports measuring of
 * the CPU time for the current  thread.
 * A Java virtual machine implementation that supports CPU time measurement
 * for any thread will also support that for the current thread.
 *
 * <p> The CPU time provided by this interface has nanosecond precision
 * but not necessarily nanosecond accuracy.
 *
 * <p>
 * A Java virtual machine may disable CPU time measurement
 * by default.
 * The {@link #isThreadCpuTimeEnabled} and {@link #setThreadCpuTimeEnabled}
 * methods can be used to test if CPU time measurement is enabled
 * and to enable/disable this support respectively.
 * Enabling thread CPU measurement could be expensive in some
 * Java virtual machine implementations.
 *
 * <h3>Thread Contention Monitoring</h3>
 * Some Java virtual machines may support thread contention monitoring.
 * When thread contention monitoring is enabled, the accumulated elapsed
 * time that the thread has blocked for synchronization or waited for
 * notification will be collected and returned in the
 * <a href="ThreadInfo.html#SyncStats">{@code ThreadInfo}</a> object.
 * <p>
 * The {@link #isThreadContentionMonitoringSupported} method can be used to
 * determine if a Java virtual machine supports thread contention monitoring.
 * The thread contention monitoring is disabled by default.  The
 * {@link #setThreadContentionMonitoringEnabled} method can be used to enable
 * thread contention monitoring.
 *
 * <h3>Synchronization Information and Deadlock Detection</h3>
 * Some Java virtual machines may support monitoring of
 * {@linkplain #isObjectMonitorUsageSupported object monitor usage} and
 * {@linkplain #isSynchronizerUsageSupported ownable synchronizer usage}.
 * The {@link #getThreadInfo(long[], boolean, boolean)} and
 * {@link #dumpAllThreads} methods can be used to obtain the thread stack trace
 * and synchronization information including which
 * {@linkplain LockInfo <i>lock</i>} a thread is blocked to
 * acquire or waiting on and which locks the thread currently owns.
 * <p>
 * The {@code ThreadMXBean} interface provides the
 * {@link #findMonitorDeadlockedThreads} and
 * {@link #findDeadlockedThreads} methods to find deadlocks in
 * the running application.
 *
 * @see ManagementFactory#getPlatformMXBeans(Class)
 * @see <a href="../../../javax/management/package-summary.html">
 *      JMX Specification.</a>
 * @see <a href="package-summary.html#examples">
 *      Ways to Access MXBeans</a>
 *
 * @author  Mandy Chung
 * @since   1.5
 */

public interface ThreadMXBean extends PlatformManagedObject {
    
Returns the current number of live threads including both
daemon and non-daemon threads.

Returns:the current number of live threads.
/**
     * Returns the current number of live threads including both
     * daemon and non-daemon threads.
     *
     * @return the current number of live threads.
     */
    public int getThreadCount();

    
Returns the peak live thread count since the Java virtual machine
started or peak was reset.

Returns:the peak live thread count.
/**
     * Returns the peak live thread count since the Java virtual machine
     * started or peak was reset.
     *
     * @return the peak live thread count.
     */
    public int getPeakThreadCount();

    
Returns the total number of threads created and also started
since the Java virtual machine started.

Returns:the total number of threads started.
/**
     * Returns the total number of threads created and also started
     * since the Java virtual machine started.
     *
     * @return the total number of threads started.
     */
    public long getTotalStartedThreadCount();

    
Returns the current number of live daemon threads.

Returns:the current number of live daemon threads.
/**
     * Returns the current number of live daemon threads.
     *
     * @return the current number of live daemon threads.
     */
    public int getDaemonThreadCount();

    
Returns all live thread IDs.
Some threads included in the returned array
may have been terminated when this method returns.

Throws:
  • SecurityException – if a security manager
        exists and the caller does not have
        ManagementPermission("monitor").
Returns:an array of long, each is a thread ID.
/**
     * Returns all live thread IDs.
     * Some threads included in the returned array
     * may have been terminated when this method returns.
     *
     * @return an array of {@code long}, each is a thread ID.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     */
    public long[] getAllThreadIds();

    
Returns the thread info for a thread of the specified id with no stack trace. This method is equivalent to calling: 
 getThreadInfo(id, 0); 


 This method returns a ThreadInfo object representing the thread information for the thread of the specified ID. The stack trace, locked monitors, and locked synchronizers in the returned ThreadInfo object will be empty. If a thread of the given ID is not alive or does not exist, this method will return null. A thread is alive if it has been started and has not yet died. 

MBeanServer access:
 The mapped type of ThreadInfo is CompositeData with attributes as specified in the ThreadInfo.from method. 
Params:
  • id – the thread ID of the thread. Must be positive.
Throws:
Returns:a ThreadInfo object for the thread of the given ID with no stack trace, no locked monitor and no synchronizer info; null if the thread of the given ID is not alive or it does not exist.
/**
     * Returns the thread info for a thread of the specified
     * {@code id} with no stack trace.
     * This method is equivalent to calling:
     * <blockquote>
     *   {@link #getThreadInfo(long, int) getThreadInfo(id, 0);}
     * </blockquote>
     *
     * <p>
     * This method returns a {@code ThreadInfo} object representing
     * the thread information for the thread of the specified ID.
     * The stack trace, locked monitors, and locked synchronizers
     * in the returned {@code ThreadInfo} object will
     * be empty.
     *
     * If a thread of the given ID is not alive or does not exist,
     * this method will return {@code null}.  A thread is alive if
     * it has been started and has not yet died.
     *
     * <p>
     * <b>MBeanServer access</b>:<br>
     * The mapped type of {@code ThreadInfo} is
     * {@code CompositeData} with attributes as specified in the
     * {@link ThreadInfo#from ThreadInfo.from} method.
     *
     * @param id the thread ID of the thread. Must be positive.
     *
     * @return a {@link ThreadInfo} object for the thread of the given ID
     * with no stack trace, no locked monitor and no synchronizer info;
     * {@code null} if the thread of the given ID is not alive or
     * it does not exist.
     *
     * @throws IllegalArgumentException if {@code id <= 0}.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     */
    public ThreadInfo getThreadInfo(long id);

    
Returns the thread info for each thread whose ID is in the input array ids with no stack trace. This method is equivalent to calling: 
 getThreadInfo(ids, 0); 


 This method returns an array of the ThreadInfo objects. The stack trace, locked monitors, and locked synchronizers in each ThreadInfo object will be empty. If a thread of a given ID is not alive or does not exist, the corresponding element in the returned array will contain null. A thread is alive if it has been started and has not yet died. 

MBeanServer access:
 The mapped type of ThreadInfo is CompositeData with attributes as specified in the ThreadInfo.from method. 
Params:
  • ids – an array of thread IDs.
Throws:
Returns:an array of the ThreadInfo objects, each containing information about a thread whose ID is in the corresponding element of the input array of IDs with no stack trace, no locked monitor and no synchronizer info.
/**
     * Returns the thread info for each thread
     * whose ID is in the input array {@code ids} with no stack trace.
     * This method is equivalent to calling:
     * <blockquote><pre>
     *   {@link #getThreadInfo(long[], int) getThreadInfo}(ids, 0);
     * </pre></blockquote>
     *
     * <p>
     * This method returns an array of the {@code ThreadInfo} objects.
     * The stack trace, locked monitors, and locked synchronizers
     * in each {@code ThreadInfo} object will be empty.
     *
     * If a thread of a given ID is not alive or does not exist,
     * the corresponding element in the returned array will
     * contain {@code null}.  A thread is alive if
     * it has been started and has not yet died.
     *
     * <p>
     * <b>MBeanServer access</b>:<br>
     * The mapped type of {@code ThreadInfo} is
     * {@code CompositeData} with attributes as specified in the
     * {@link ThreadInfo#from ThreadInfo.from} method.
     *
     * @param ids an array of thread IDs.
     * @return an array of the {@link ThreadInfo} objects, each containing
     * information about a thread whose ID is in the corresponding
     * element of the input array of IDs
     * with no stack trace, no locked monitor and no synchronizer info.
     *
     * @throws IllegalArgumentException if any element in the input array
     *         {@code ids} is {@code <= 0}.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     */
    public ThreadInfo[] getThreadInfo(long[] ids);

    
Returns a thread info for a thread of the specified id, with stack trace of a specified number of stack trace elements. The maxDepth parameter indicates the maximum number of StackTraceElement to be retrieved from the stack trace. If maxDepth == Integer.MAX_VALUE, the entire stack trace of the thread will be dumped. If maxDepth == 0, no stack trace of the thread will be dumped. This method does not obtain the locked monitors and locked synchronizers of the thread. 
 When the Java virtual machine has no stack trace information about a thread or maxDepth == 0, the stack trace in the ThreadInfo object will be an empty array of StackTraceElement. 
 If a thread of the given ID is not alive or does not exist, this method will return null. A thread is alive if it has been started and has not yet died. 

MBeanServer access:
 The mapped type of ThreadInfo is CompositeData with attributes as specified in the ThreadInfo.from method. 
Params:
  • id – the thread ID of the thread. Must be positive.
  • maxDepth – the maximum number of entries in the stack trace to be dumped. Integer.MAX_VALUE could be used to request the entire stack to be dumped.
Throws:
Returns:a ThreadInfo of the thread of the given ID with no locked monitor and synchronizer info. null if the thread of the given ID is not alive or it does not exist.
/**
     * Returns a thread info for a thread of the specified {@code id},
     * with stack trace of a specified number of stack trace elements.
     * The {@code maxDepth} parameter indicates the maximum number of
     * {@link StackTraceElement} to be retrieved from the stack trace.
     * If {@code maxDepth == Integer.MAX_VALUE}, the entire stack trace of
     * the thread will be dumped.
     * If {@code maxDepth == 0}, no stack trace of the thread
     * will be dumped.
     * This method does not obtain the locked monitors and locked
     * synchronizers of the thread.
     * <p>
     * When the Java virtual machine has no stack trace information
     * about a thread or {@code maxDepth == 0},
     * the stack trace in the
     * {@code ThreadInfo} object will be an empty array of
     * {@code StackTraceElement}.
     *
     * <p>
     * If a thread of the given ID is not alive or does not exist,
     * this method will return {@code null}.  A thread is alive if
     * it has been started and has not yet died.
     *
     * <p>
     * <b>MBeanServer access</b>:<br>
     * The mapped type of {@code ThreadInfo} is
     * {@code CompositeData} with attributes as specified in the
     * {@link ThreadInfo#from ThreadInfo.from} method.
     *
     * @param id the thread ID of the thread. Must be positive.
     * @param maxDepth the maximum number of entries in the stack trace
     * to be dumped. {@code Integer.MAX_VALUE} could be used to request
     * the entire stack to be dumped.
     *
     * @return a {@link ThreadInfo} of the thread of the given ID
     * with no locked monitor and synchronizer info.
     * {@code null} if the thread of the given ID is not alive or
     * it does not exist.
     *
     * @throws IllegalArgumentException if {@code id <= 0}.
     * @throws IllegalArgumentException if {@code maxDepth is negative}.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     *
     */
    public ThreadInfo getThreadInfo(long id, int maxDepth);

    
Returns the thread info for each thread whose ID is in the input array ids, with stack trace of a specified number of stack trace elements. The maxDepth parameter indicates the maximum number of StackTraceElement to be retrieved from the stack trace. If maxDepth == Integer.MAX_VALUE, the entire stack trace of the thread will be dumped. If maxDepth == 0, no stack trace of the thread will be dumped. This method does not obtain the locked monitors and locked synchronizers of the threads. 
 When the Java virtual machine has no stack trace information about a thread or maxDepth == 0, the stack trace in the ThreadInfo object will be an empty array of StackTraceElement. 
 This method returns an array of the ThreadInfo objects, each is the thread information about the thread with the same index as in the ids array. If a thread of the given ID is not alive or does not exist, null will be set in the corresponding element in the returned array. A thread is alive if it has been started and has not yet died. 

MBeanServer access:
 The mapped type of ThreadInfo is CompositeData with attributes as specified in the ThreadInfo.from method. 
Params:
  • ids – an array of thread IDs
  • maxDepth – the maximum number of entries in the stack trace to be dumped. Integer.MAX_VALUE could be used to request the entire stack to be dumped.
Throws:
Returns:an array of the ThreadInfo objects, each containing information about a thread whose ID is in the corresponding element of the input array of IDs with no locked monitor and synchronizer info.
/**
     * Returns the thread info for each thread
     * whose ID is in the input array {@code ids},
     * with stack trace of a specified number of stack trace elements.
     * The {@code maxDepth} parameter indicates the maximum number of
     * {@link StackTraceElement} to be retrieved from the stack trace.
     * If {@code maxDepth == Integer.MAX_VALUE}, the entire stack trace of
     * the thread will be dumped.
     * If {@code maxDepth == 0}, no stack trace of the thread
     * will be dumped.
     * This method does not obtain the locked monitors and locked
     * synchronizers of the threads.
     * <p>
     * When the Java virtual machine has no stack trace information
     * about a thread or {@code maxDepth == 0},
     * the stack trace in the
     * {@code ThreadInfo} object will be an empty array of
     * {@code StackTraceElement}.
     * <p>
     * This method returns an array of the {@code ThreadInfo} objects,
     * each is the thread information about the thread with the same index
     * as in the {@code ids} array.
     * If a thread of the given ID is not alive or does not exist,
     * {@code null} will be set in the corresponding element
     * in the returned array.  A thread is alive if
     * it has been started and has not yet died.
     *
     * <p>
     * <b>MBeanServer access</b>:<br>
     * The mapped type of {@code ThreadInfo} is
     * {@code CompositeData} with attributes as specified in the
     * {@link ThreadInfo#from ThreadInfo.from} method.
     *
     * @param ids an array of thread IDs
     * @param maxDepth the maximum number of entries in the stack trace
     * to be dumped. {@code Integer.MAX_VALUE} could be used to request
     * the entire stack to be dumped.
     *
     * @return an array of the {@link ThreadInfo} objects, each containing
     * information about a thread whose ID is in the corresponding
     * element of the input array of IDs with no locked monitor and
     * synchronizer info.
     *
     * @throws IllegalArgumentException if {@code maxDepth is negative}.
     * @throws IllegalArgumentException if any element in the input array
     *      {@code ids} is {@code <= 0}.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     *
     */
    public ThreadInfo[] getThreadInfo(long[] ids, int maxDepth);

    
Tests if the Java virtual machine supports thread contention monitoring.

Returns: true if the Java virtual machine supports thread contention monitoring; false otherwise.
/**
     * Tests if the Java virtual machine supports thread contention monitoring.
     *
     * @return
     *   {@code true}
     *     if the Java virtual machine supports thread contention monitoring;
     *   {@code false} otherwise.
     */
    public boolean isThreadContentionMonitoringSupported();

    
Tests if thread contention monitoring is enabled.

Throws:
See Also:
Returns:true if thread contention monitoring is enabled; false otherwise.
/**
     * Tests if thread contention monitoring is enabled.
     *
     * @return {@code true} if thread contention monitoring is enabled;
     *         {@code false} otherwise.
     *
     * @throws UnsupportedOperationException if the Java virtual
     * machine does not support thread contention monitoring.
     *
     * @see #isThreadContentionMonitoringSupported
     */
    public boolean isThreadContentionMonitoringEnabled();

    
Enables or disables thread contention monitoring.
Thread contention monitoring is disabled by default.

Params:
  • enable – true to enable; false to disable.
Throws:
See Also:
/**
     * Enables or disables thread contention monitoring.
     * Thread contention monitoring is disabled by default.
     *
     * @param enable {@code true} to enable;
     *               {@code false} to disable.
     *
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support thread contention monitoring.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("control").
     *
     * @see #isThreadContentionMonitoringSupported
     */
    public void setThreadContentionMonitoringEnabled(boolean enable);

    
Returns the total CPU time for the current thread in nanoseconds.
The returned value is of nanoseconds precision but
not necessarily nanoseconds accuracy.
If the implementation distinguishes between user mode time and system
mode time, the returned CPU time is the amount of time that
the current thread has executed in user mode or system mode.


This is a convenience method for local management use and is
equivalent to calling:

 getThreadCpuTime(Thread.currentThread().getId()); 


Throws:
See Also:
Returns:the total CPU time for the current thread if CPU time measurement is enabled; -1 otherwise.
/**
     * Returns the total CPU time for the current thread in nanoseconds.
     * The returned value is of nanoseconds precision but
     * not necessarily nanoseconds accuracy.
     * If the implementation distinguishes between user mode time and system
     * mode time, the returned CPU time is the amount of time that
     * the current thread has executed in user mode or system mode.
     *
     * <p>
     * This is a convenience method for local management use and is
     * equivalent to calling:
     * <blockquote><pre>
     *   {@link #getThreadCpuTime getThreadCpuTime}(Thread.currentThread().getId());
     * </pre></blockquote>
     *
     * @return the total CPU time for the current thread if CPU time
     * measurement is enabled; {@code -1} otherwise.
     *
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support CPU time measurement for
     * the current thread.
     *
     * @see #getCurrentThreadUserTime
     * @see #isCurrentThreadCpuTimeSupported
     * @see #isThreadCpuTimeEnabled
     * @see #setThreadCpuTimeEnabled
     */
    public long getCurrentThreadCpuTime();

    
Returns the CPU time that the current thread has executed
in user mode in nanoseconds.
The returned value is of nanoseconds precision but
not necessarily nanoseconds accuracy.


This is a convenience method for local management use and is
equivalent to calling:

 getThreadUserTime(Thread.currentThread().getId()); 


Throws:
See Also:
Returns:the user-level CPU time for the current thread if CPU time measurement is enabled; -1 otherwise.
/**
     * Returns the CPU time that the current thread has executed
     * in user mode in nanoseconds.
     * The returned value is of nanoseconds precision but
     * not necessarily nanoseconds accuracy.
     *
     * <p>
     * This is a convenience method for local management use and is
     * equivalent to calling:
     * <blockquote><pre>
     *   {@link #getThreadUserTime getThreadUserTime}(Thread.currentThread().getId());
     * </pre></blockquote>
     *
     * @return the user-level CPU time for the current thread if CPU time
     * measurement is enabled; {@code -1} otherwise.
     *
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support CPU time measurement for
     * the current thread.
     *
     * @see #getCurrentThreadCpuTime
     * @see #isCurrentThreadCpuTimeSupported
     * @see #isThreadCpuTimeEnabled
     * @see #setThreadCpuTimeEnabled
     */
    public long getCurrentThreadUserTime();

    
Returns the total CPU time for a thread of the specified ID in nanoseconds.
The returned value is of nanoseconds precision but
not necessarily nanoseconds accuracy.
If the implementation distinguishes between user mode time and system
mode time, the returned CPU time is the amount of time that
the thread has executed in user mode or system mode.

 If the thread of the specified ID is not alive or does not exist, this method returns -1. If CPU time measurement is disabled, this method returns -1. A thread is alive if it has been started and has not yet died. 

If CPU time measurement is enabled after the thread has started,
the Java virtual machine implementation may choose any time up to
and including the time that the capability is enabled as the point
where CPU time measurement starts.

Params:
  • id – the thread ID of a thread
Throws:
See Also:
Returns:the total CPU time for a thread of the specified ID if the thread of the specified ID exists, the thread is alive, and CPU time measurement is enabled; -1 otherwise.
/**
     * Returns the total CPU time for a thread of the specified ID in nanoseconds.
     * The returned value is of nanoseconds precision but
     * not necessarily nanoseconds accuracy.
     * If the implementation distinguishes between user mode time and system
     * mode time, the returned CPU time is the amount of time that
     * the thread has executed in user mode or system mode.
     *
     * <p>
     * If the thread of the specified ID is not alive or does not exist,
     * this method returns {@code -1}. If CPU time measurement
     * is disabled, this method returns {@code -1}.
     * A thread is alive if it has been started and has not yet died.
     * <p>
     * If CPU time measurement is enabled after the thread has started,
     * the Java virtual machine implementation may choose any time up to
     * and including the time that the capability is enabled as the point
     * where CPU time measurement starts.
     *
     * @param id the thread ID of a thread
     * @return the total CPU time for a thread of the specified ID
     * if the thread of the specified ID exists, the thread is alive,
     * and CPU time measurement is enabled;
     * {@code -1} otherwise.
     *
     * @throws IllegalArgumentException if {@code id <= 0}.
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support CPU time measurement for
     * other threads.
     *
     * @see #getThreadUserTime
     * @see #isThreadCpuTimeSupported
     * @see #isThreadCpuTimeEnabled
     * @see #setThreadCpuTimeEnabled
     */
    public long getThreadCpuTime(long id);

    
Returns the CPU time that a thread of the specified ID
has executed in user mode in nanoseconds.
The returned value is of nanoseconds precision but
not necessarily nanoseconds accuracy.

 If the thread of the specified ID is not alive or does not exist, this method returns -1. If CPU time measurement is disabled, this method returns -1. A thread is alive if it has been started and has not yet died. 

If CPU time measurement is enabled after the thread has started,
the Java virtual machine implementation may choose any time up to
and including the time that the capability is enabled as the point
where CPU time measurement starts.

Params:
  • id – the thread ID of a thread
Throws:
See Also:
Returns:the user-level CPU time for a thread of the specified ID if the thread of the specified ID exists, the thread is alive, and CPU time measurement is enabled; -1 otherwise.
/**
     * Returns the CPU time that a thread of the specified ID
     * has executed in user mode in nanoseconds.
     * The returned value is of nanoseconds precision but
     * not necessarily nanoseconds accuracy.
     *
     * <p>
     * If the thread of the specified ID is not alive or does not exist,
     * this method returns {@code -1}. If CPU time measurement
     * is disabled, this method returns {@code -1}.
     * A thread is alive if it has been started and has not yet died.
     * <p>
     * If CPU time measurement is enabled after the thread has started,
     * the Java virtual machine implementation may choose any time up to
     * and including the time that the capability is enabled as the point
     * where CPU time measurement starts.
     *
     * @param id the thread ID of a thread
     * @return the user-level CPU time for a thread of the specified ID
     * if the thread of the specified ID exists, the thread is alive,
     * and CPU time measurement is enabled;
     * {@code -1} otherwise.
     *
     * @throws IllegalArgumentException if {@code id <= 0}.
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support CPU time measurement for
     * other threads.
     *
     * @see #getThreadCpuTime
     * @see #isThreadCpuTimeSupported
     * @see #isThreadCpuTimeEnabled
     * @see #setThreadCpuTimeEnabled
     */
    public long getThreadUserTime(long id);

    
Tests if the Java virtual machine implementation supports CPU time
measurement for any thread.
A Java virtual machine implementation that supports CPU time
measurement for any thread will also support CPU time
measurement for the current thread.

Returns: true if the Java virtual machine supports CPU time measurement for any thread; false otherwise.
/**
     * Tests if the Java virtual machine implementation supports CPU time
     * measurement for any thread.
     * A Java virtual machine implementation that supports CPU time
     * measurement for any thread will also support CPU time
     * measurement for the current thread.
     *
     * @return
     *   {@code true}
     *     if the Java virtual machine supports CPU time
     *     measurement for any thread;
     *   {@code false} otherwise.
     */
    public boolean isThreadCpuTimeSupported();

    
Tests if the Java virtual machine supports CPU time measurement for the current thread. This method returns true if isThreadCpuTimeSupported returns true. 
Returns: true if the Java virtual machine supports CPU time measurement for current thread; false otherwise.
/**
     * Tests if the Java virtual machine supports CPU time
     * measurement for the current thread.
     * This method returns {@code true} if {@link #isThreadCpuTimeSupported}
     * returns {@code true}.
     *
     * @return
     *   {@code true}
     *     if the Java virtual machine supports CPU time
     *     measurement for current thread;
     *   {@code false} otherwise.
     */
    public boolean isCurrentThreadCpuTimeSupported();

    
Tests if thread CPU time measurement is enabled.

Throws:
  • UnsupportedOperationException – if the Java virtual
machine does not support CPU time measurement for other threads
nor for the current thread.
See Also:
Returns:true if thread CPU time measurement is enabled; false otherwise.
/**
     * Tests if thread CPU time measurement is enabled.
     *
     * @return {@code true} if thread CPU time measurement is enabled;
     *         {@code false} otherwise.
     *
     * @throws UnsupportedOperationException if the Java virtual
     * machine does not support CPU time measurement for other threads
     * nor for the current thread.
     *
     * @see #isThreadCpuTimeSupported
     * @see #isCurrentThreadCpuTimeSupported
     */
    public boolean isThreadCpuTimeEnabled();

    
Enables or disables thread CPU time measurement.  The default
is platform dependent.

Params:
  • enable – true to enable; false to disable.
Throws:
  • UnsupportedOperationException – if the Java
virtual machine does not support CPU time measurement for
any threads nor for the current thread.
  • SecurityException – if a security manager
        exists and the caller does not have
        ManagementPermission("control").
See Also:
/**
     * Enables or disables thread CPU time measurement.  The default
     * is platform dependent.
     *
     * @param enable {@code true} to enable;
     *               {@code false} to disable.
     *
     * @throws UnsupportedOperationException if the Java
     * virtual machine does not support CPU time measurement for
     * any threads nor for the current thread.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("control").
     *
     * @see #isThreadCpuTimeSupported
     * @see #isCurrentThreadCpuTimeSupported
     */
    public void setThreadCpuTimeEnabled(boolean enable);

    
Finds cycles of threads that are in deadlock waiting to acquire object monitors. That is, threads that are blocked waiting to enter a synchronization block or waiting to reenter a synchronization block after an Object.wait call, where each thread owns one monitor while trying to obtain another monitor already held by another thread in a cycle. 

More formally, a thread is monitor deadlocked if it is
part of a cycle in the relation "is waiting for an object monitor
owned by".  In the simplest case, thread A is blocked waiting
for a monitor owned by thread B, and thread B is blocked waiting
for a monitor owned by thread A.


This method is designed for troubleshooting use, but not for
synchronization control.  It might be an expensive operation.


This method finds deadlocks involving only object monitors.
To find deadlocks involving both object monitors and
ownable synchronizers, the findDeadlockedThreads method should be used. 
Throws:
  • SecurityException – if a security manager
        exists and the caller does not have
        ManagementPermission("monitor").
See Also:
Returns:an array of IDs of the threads that are monitor deadlocked, if any; null otherwise.
/**
     * Finds cycles of threads that are in deadlock waiting to acquire
     * object monitors. That is, threads that are blocked waiting to enter a
     * synchronization block or waiting to reenter a synchronization block
     * after an {@link Object#wait Object.wait} call,
     * where each thread owns one monitor while
     * trying to obtain another monitor already held by another thread
     * in a cycle.
     * <p>
     * More formally, a thread is <em>monitor deadlocked</em> if it is
     * part of a cycle in the relation "is waiting for an object monitor
     * owned by".  In the simplest case, thread A is blocked waiting
     * for a monitor owned by thread B, and thread B is blocked waiting
     * for a monitor owned by thread A.
     * <p>
     * This method is designed for troubleshooting use, but not for
     * synchronization control.  It might be an expensive operation.
     * <p>
     * This method finds deadlocks involving only object monitors.
     * To find deadlocks involving both object monitors and
     * <a href="LockInfo.html#OwnableSynchronizer">ownable synchronizers</a>,
     * the {@link #findDeadlockedThreads findDeadlockedThreads} method
     * should be used.
     *
     * @return an array of IDs of the threads that are monitor
     * deadlocked, if any; {@code null} otherwise.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     *
     * @see #findDeadlockedThreads
     */
    public long[] findMonitorDeadlockedThreads();

    
Resets the peak thread count to the current number of
live threads.

Throws:
  • SecurityException – if a security manager
        exists and the caller does not have
        ManagementPermission("control").
See Also:
/**
     * Resets the peak thread count to the current number of
     * live threads.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("control").
     *
     * @see #getPeakThreadCount
     * @see #getThreadCount
     */
    public void resetPeakThreadCount();

    
Finds cycles of threads that are in deadlock waiting to acquire
object monitors or
ownable synchronizers.
Threads are deadlocked in a cycle waiting for a lock of
these two types if each thread owns one lock while
trying to acquire another lock already held
by another thread in the cycle.


This method is designed for troubleshooting use, but not for
synchronization control.  It might be an expensive operation.

Throws:
  • SecurityException – if a security manager
        exists and the caller does not have
        ManagementPermission("monitor").
  • UnsupportedOperationException – if the Java virtual
machine does not support monitoring of ownable synchronizer usage.
See Also:
Returns:an array of IDs of the threads that are deadlocked waiting for object monitors or ownable synchronizers, if any; null otherwise.
Since:1.6
/**
     * Finds cycles of threads that are in deadlock waiting to acquire
     * object monitors or
     * <a href="LockInfo.html#OwnableSynchronizer">ownable synchronizers</a>.
     *
     * Threads are <em>deadlocked</em> in a cycle waiting for a lock of
     * these two types if each thread owns one lock while
     * trying to acquire another lock already held
     * by another thread in the cycle.
     * <p>
     * This method is designed for troubleshooting use, but not for
     * synchronization control.  It might be an expensive operation.
     *
     * @return an array of IDs of the threads that are
     * deadlocked waiting for object monitors or ownable synchronizers, if any;
     * {@code null} otherwise.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     * @throws UnsupportedOperationException if the Java virtual
     * machine does not support monitoring of ownable synchronizer usage.
     *
     * @see #isSynchronizerUsageSupported
     * @see #findMonitorDeadlockedThreads
     * @since 1.6
     */
    public long[] findDeadlockedThreads();

    
Tests if the Java virtual machine supports monitoring of
object monitor usage.

See Also:
Returns: true if the Java virtual machine supports monitoring of object monitor usage; false otherwise.
Since:1.6
/**
     * Tests if the Java virtual machine supports monitoring of
     * object monitor usage.
     *
     * @return
     *   {@code true}
     *     if the Java virtual machine supports monitoring of
     *     object monitor usage;
     *   {@code false} otherwise.
     *
     * @see #dumpAllThreads
     * @since 1.6
     */
    public boolean isObjectMonitorUsageSupported();

    
Tests if the Java virtual machine supports monitoring of

ownable synchronizer usage.

See Also:
Returns: true if the Java virtual machine supports monitoring of ownable synchronizer usage; false otherwise.
Since:1.6
/**
     * Tests if the Java virtual machine supports monitoring of
     * <a href="LockInfo.html#OwnableSynchronizer">
     * ownable synchronizer</a> usage.
     *
     * @return
     *   {@code true}
     *     if the Java virtual machine supports monitoring of ownable
     *     synchronizer usage;
     *   {@code false} otherwise.
     *
     * @see #dumpAllThreads
     * @since 1.6
     */
    public boolean isSynchronizerUsageSupported();

    
Returns the thread info for each thread whose ID is in the input array ids, with stack trace and synchronization information. This is equivalent to calling: 
 
getThreadInfo(ids, lockedMonitors, lockedSynchronizers, Integer.MAX_VALUE) 


Params:
  • ids – an array of thread IDs.
  • lockedMonitors – if true, retrieves all locked monitors.
  • lockedSynchronizers – if true, retrieves all locked ownable synchronizers.
Throws:
See Also:
Returns:an array of the ThreadInfo objects, each containing information about a thread whose ID is in the corresponding element of the input array of IDs.
Since:1.6
/**
     * Returns the thread info for each thread
     * whose ID is in the input array {@code ids},
     * with stack trace and synchronization information.
     * This is equivalent to calling:
     * <blockquote>
     * {@link #getThreadInfo(long[], boolean, boolean, int)
     * getThreadInfo(ids, lockedMonitors, lockedSynchronizers, Integer.MAX_VALUE)}
     * </blockquote>
     *
     * @param  ids an array of thread IDs.
     * @param  lockedMonitors if {@code true}, retrieves all locked monitors.
     * @param  lockedSynchronizers if {@code true}, retrieves all locked
     *             ownable synchronizers.
     *
     * @return an array of the {@link ThreadInfo} objects, each containing
     * information about a thread whose ID is in the corresponding
     * element of the input array of IDs.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     * @throws UnsupportedOperationException
     *         <ul>
     *           <li>if {@code lockedMonitors} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isObjectMonitorUsageSupported
     *               object monitor usage}; or</li>
     *           <li>if {@code lockedSynchronizers} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isSynchronizerUsageSupported
     *               ownable synchronizer usage}.</li>
     *         </ul>
     *
     * @see #isObjectMonitorUsageSupported
     * @see #isSynchronizerUsageSupported
     *
     * @since 1.6
     */
    public ThreadInfo[] getThreadInfo(long[] ids, boolean lockedMonitors,
                                      boolean lockedSynchronizers);

    
Returns the thread info for each thread whose ID is in the input array ids, with stack trace of the specified maximum number of elements and synchronization information. If maxDepth == 0, no stack trace of the thread will be dumped. 

This method obtains a snapshot of the thread information
for each thread including:

    
   
  • stack trace of the specified maximum number of elements,
    • 
   
  • the object monitors currently locked by the thread if lockedMonitors is true, and
    • 
   
  • the 
       ownable synchronizers currently locked by the thread if lockedSynchronizers is true.
    • 



 This method returns an array of the ThreadInfo objects, each is the thread information about the thread with the same index as in the ids array. If a thread of the given ID is not alive or does not exist, null will be set in the corresponding element in the returned array. A thread is alive if it has been started and has not yet died. 
 If a thread does not lock any object monitor or lockedMonitors is false, the returned ThreadInfo object will have an empty MonitorInfo array. Similarly, if a thread does not lock any synchronizer or lockedSynchronizers is false, the returned ThreadInfo object will have an empty LockInfo array. 
 When both lockedMonitors and lockedSynchronizers parameters are false, it is equivalent to calling: 
  getThreadInfo(ids, maxDepth) 



This method is designed for troubleshooting use, but not for
synchronization control.  It might be an expensive operation.


MBeanServer access:
 The mapped type of ThreadInfo is CompositeData with attributes as specified in the ThreadInfo.from method. 
Params:
  • ids – an array of thread IDs.
  • lockedMonitors – if true, retrieves all locked monitors.
  • lockedSynchronizers – if true, retrieves all locked ownable synchronizers.
  • maxDepth – indicates the maximum number of StackTraceElement to be retrieved from the stack trace.
Throws:
See Also:
Implementation Requirements:The default implementation throws UnsupportedOperationException.
Returns:an array of the ThreadInfo objects, each containing information about a thread whose ID is in the corresponding element of the input array of IDs.
Since:10
/**
     * Returns the thread info for each thread whose ID
     * is in the input array {@code ids},
     * with stack trace of the specified maximum number of elements
     * and synchronization information.
     * If {@code maxDepth == 0}, no stack trace of the thread
     * will be dumped.
     *
     * <p>
     * This method obtains a snapshot of the thread information
     * for each thread including:
     * <ul>
     *    <li>stack trace of the specified maximum number of elements,</li>
     *    <li>the object monitors currently locked by the thread
     *        if {@code lockedMonitors} is {@code true}, and</li>
     *    <li>the <a href="LockInfo.html#OwnableSynchronizer">
     *        ownable synchronizers</a> currently locked by the thread
     *        if {@code lockedSynchronizers} is {@code true}.</li>
     * </ul>
     * <p>
     * This method returns an array of the {@code ThreadInfo} objects,
     * each is the thread information about the thread with the same index
     * as in the {@code ids} array.
     * If a thread of the given ID is not alive or does not exist,
     * {@code null} will be set in the corresponding element
     * in the returned array.  A thread is alive if
     * it has been started and has not yet died.
     * <p>
     * If a thread does not lock any object monitor or {@code lockedMonitors}
     * is {@code false}, the returned {@code ThreadInfo} object will have an
     * empty {@code MonitorInfo} array.  Similarly, if a thread does not
     * lock any synchronizer or {@code lockedSynchronizers} is {@code false},
     * the returned {@code ThreadInfo} object
     * will have an empty {@code LockInfo} array.
     *
     * <p>
     * When both {@code lockedMonitors} and {@code lockedSynchronizers}
     * parameters are {@code false}, it is equivalent to calling:
     * <blockquote><pre>
     *     {@link #getThreadInfo(long[], int)  getThreadInfo(ids, maxDepth)}
     * </pre></blockquote>
     *
     * <p>
     * This method is designed for troubleshooting use, but not for
     * synchronization control.  It might be an expensive operation.
     *
     * <p>
     * <b>MBeanServer access</b>:<br>
     * The mapped type of {@code ThreadInfo} is
     * {@code CompositeData} with attributes as specified in the
     * {@link ThreadInfo#from ThreadInfo.from} method.
     *
     * @implSpec The default implementation throws
     * {@code UnsupportedOperationException}.
     *
     * @param  ids an array of thread IDs.
     * @param  lockedMonitors if {@code true}, retrieves all locked monitors.
     * @param  lockedSynchronizers if {@code true}, retrieves all locked
     *             ownable synchronizers.
     * @param  maxDepth indicates the maximum number of
     * {@link StackTraceElement} to be retrieved from the stack trace.
     *
     * @return an array of the {@link ThreadInfo} objects, each containing
     * information about a thread whose ID is in the corresponding
     * element of the input array of IDs.
     *
     * @throws IllegalArgumentException if {@code maxDepth} is negative.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     * @throws UnsupportedOperationException
     *         <ul>
     *           <li>if {@code lockedMonitors} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isObjectMonitorUsageSupported
     *               object monitor usage}; or</li>
     *           <li>if {@code lockedSynchronizers} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isSynchronizerUsageSupported
     *               ownable synchronizer usage}.</li>
     *         </ul>
     *
     * @see #isObjectMonitorUsageSupported
     * @see #isSynchronizerUsageSupported
     *
     * @since 10
     */

    public default ThreadInfo[] getThreadInfo(long[] ids, boolean lockedMonitors,
                                              boolean lockedSynchronizers, int maxDepth) {
        throw new UnsupportedOperationException();
    }

    
Returns the thread info for all live threads with stack trace
and synchronization information.
This is equivalent to calling:

 
dumpAllThreads(lockedMonitors, lockedSynchronizers, Integer.MAX_VALUE) 


Params:
  • lockedMonitors – if true, dump all locked monitors.
  • lockedSynchronizers – if true, dump all locked ownable synchronizers.
Throws:
See Also:
Returns:an array of ThreadInfo for all live threads.
Since:1.6
/**
     * Returns the thread info for all live threads with stack trace
     * and synchronization information.
     * This is equivalent to calling:
     * <blockquote>
     * {@link #dumpAllThreads(boolean, boolean, int)
     * dumpAllThreads(lockedMonitors, lockedSynchronizers, Integer.MAX_VALUE)}
     * </blockquote>
     *
     * @param  lockedMonitors if {@code true}, dump all locked monitors.
     * @param  lockedSynchronizers if {@code true}, dump all locked
     *             ownable synchronizers.
     *
     * @return an array of {@link ThreadInfo} for all live threads.
     *
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     * @throws UnsupportedOperationException
     *         <ul>
     *           <li>if {@code lockedMonitors} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isObjectMonitorUsageSupported
     *               object monitor usage}; or</li>
     *           <li>if {@code lockedSynchronizers} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isSynchronizerUsageSupported
     *               ownable synchronizer usage}.</li>
     *         </ul>
     *
     * @see #isObjectMonitorUsageSupported
     * @see #isSynchronizerUsageSupported
     *
     * @since 1.6
     */
    public ThreadInfo[] dumpAllThreads(boolean lockedMonitors, boolean lockedSynchronizers);


    
Returns the thread info for all live threads with stack trace of the specified maximum number of elements and synchronization information. if maxDepth == 0, no stack trace of the thread will be dumped. Some threads included in the returned array may have been terminated when this method returns. 
 This method returns an array of ThreadInfo objects as specified in the getThreadInfo(long[], boolean, boolean, int) method. 
Params:
  • lockedMonitors – if true, dump all locked monitors.
  • lockedSynchronizers – if true, dump all locked ownable synchronizers.
  • maxDepth – indicates the maximum number of StackTraceElement to be retrieved from the stack trace.
Throws:
See Also:
Implementation Requirements:The default implementation throws UnsupportedOperationException.
Returns:an array of ThreadInfo for all live threads.
Since:10
/**
     * Returns the thread info for all live threads
     * with stack trace of the specified maximum number of elements
     * and synchronization information.
     * if {@code maxDepth == 0}, no stack trace of the thread
     * will be dumped.
     * Some threads included in the returned array
     * may have been terminated when this method returns.
     *
     * <p>
     * This method returns an array of {@link ThreadInfo} objects
     * as specified in the {@link #getThreadInfo(long[], boolean, boolean, int)}
     * method.
     *
     * @implSpec The default implementation throws
     * {@code UnsupportedOperationException}.
     *
     * @param  lockedMonitors if {@code true}, dump all locked monitors.
     * @param  lockedSynchronizers if {@code true}, dump all locked
     *             ownable synchronizers.
     * @param  maxDepth indicates the maximum number of
     * {@link StackTraceElement} to be retrieved from the stack trace.
     *
     * @return an array of {@link ThreadInfo} for all live threads.
     *
     * @throws IllegalArgumentException if {@code maxDepth} is negative.
     * @throws SecurityException if a security manager
     *         exists and the caller does not have
     *         ManagementPermission("monitor").
     * @throws UnsupportedOperationException
     *         <ul>
     *           <li>if {@code lockedMonitors} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isObjectMonitorUsageSupported
     *               object monitor usage}; or</li>
     *           <li>if {@code lockedSynchronizers} is {@code true} but
     *               the Java virtual machine does not support monitoring
     *               of {@linkplain #isSynchronizerUsageSupported
     *               ownable synchronizer usage}.</li>
     *         </ul>
     *
     * @see #isObjectMonitorUsageSupported
     * @see #isSynchronizerUsageSupported
     *
     * @since 10
     */
    public default ThreadInfo[] dumpAllThreads(boolean lockedMonitors,
                                               boolean lockedSynchronizers, int maxDepth) {
        throw new UnsupportedOperationException();
    }
}