/*
* @(#)ThreadMXBean.java 1.14 04/04/29
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.lang.management;
/**
* 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 <tt>MBeanServer</tt>} method.
*
* <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for
* the thread system within an MBeanServer is:
* <blockquote>
* {@link ManagementFactory#THREAD_MXBEAN_NAME
* <tt>java.lang:type=Threading</tt>}
* </blockquote>
*
* <h4>Thread ID</h4>
* 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.
*
* <h4>Thread CPU time</h4>
* 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.
*
* <h4>Thread Contention Monitoring</h4>
* Some Java virtual machines may support thread contention monitoring.
* 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.
*
* @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
* @version 1.14, 04/29/04
* @since 1.5
*/
public interface ThreadMXBean {
/**
* 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.
*
* @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.
*
* @return the total number of threads started.
*/
public long getTotalStartedThreadCount();
/**
* 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.
*
* @return an array of <tt>long</tt>, each is a thread ID.
*
* @throws java.lang.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
* <tt>id</tt> with no stack trace. This method is equivalent to calling:
* <blockquote>
* {@link #getThreadInfo(long, int) getThreadInfo(id, 0);}
* </blockquote>
*
* <p>
* This method returns a <tt>ThreadInfo</tt> object representing
* the thread information for the thread of the specified ID.
* The stack trace in the returned <tt>ThreadInfo</tt> object will
* be an empty array of <tt>StackTraceElement</tt>.
*
* If a thread of the given ID is not alive or does not exist,
* this method will return <tt>null</tt>. A thread is alive if
* it has been started and has not yet died.
*
* <p>
* <b>MBeanServer access</b>:<br>
* The mapped type of <tt>ThreadInfo</tt> is
* <tt>CompositeData</tt> with attributes as specified in
* {@link ThreadInfo#from ThreadInfo}.
*
* @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;
* <tt>null</tt> if the thread of the given ID is not alive or
* it does not exist.
*
* @throws IllegalArgumentException if <tt>id <= 0</tt>.
* @throws java.lang.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 <tt>ids</tt> 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 <tt>ThreadInfo</tt> objects.
* The stack trace in each <tt>ThreadInfo</tt> object will
* be an empty array of <tt>StackTraceElement</tt>.
*
* If a thread of a given ID is not alive or does not exist,
* the corresponding element in the returned array will
* contain <tt>null</tt>. A thread is alive if
* it has been started and has not yet died.
*
* <p>
* <b>MBeanServer access</b>:<br>
* The mapped type of <tt>ThreadInfo</tt> is
* <tt>CompositeData</tt> with attributes as specified in
* {@link ThreadInfo#from ThreadInfo}.
*
* @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.
*
* @throws IllegalArgumentException if any element in the input array
* <tt>ids</tt> is <tt><= 0</tt>.
* @throws java.lang.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 <tt>id</tt>.
* The <tt>maxDepth</tt> parameter indicates the maximum number of
* <tt>StackTraceElement</tt> to be retrieved from the stack trace.
* If <tt>maxDepth == Integer.MAX_VALUE</tt>, the entire stack trace of
* the thread will be dumped.
* If <tt>maxDepth == 0</tt>, no stack trace of the thread
* will be dumped.
* <p>
* When the Java virtual machine has no stack trace information
* about a thread or <tt>maxDepth == 0</tt>,
* the stack trace in the
* <tt>ThreadInfo</tt> object will be an empty array of
* <tt>StackTraceElement</tt>.
*
* <p>
* If a thread of the given ID is not alive or does not exist,
* this method will return <tt>null</tt>. A thread is alive if
* it has been started and has not yet died.
*
* <p>
* <b>MBeanServer access</b>:<br>
* The mapped type of <tt>ThreadInfo</tt> is
* <tt>CompositeData</tt> with attributes as specified in
* {@link ThreadInfo#from ThreadInfo}.
*
* @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. <tt>Integer.MAX_VALUE</tt> could be used to request
* the entire stack to be dumped.
*
* @return a {@link ThreadInfo} of the thread of the given ID.
* <tt>null</tt> if the thread of the given ID is not alive or
* it does not exist.
*
* @throws IllegalArgumentException if <tt>id <= 0</tt>.
* @throws IllegalArgumentException if <tt>maxDepth is negative</tt>.
* @throws java.lang.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 <tt>ids</tt>.
* The <tt>maxDepth</tt> parameter indicates the maximum number of
* <tt>StackTraceElement</tt> to be retrieved from the stack trace.
* If <tt>maxDepth == Integer.MAX_VALUE</tt>, the entire stack trace of
* the thread will be dumped.
* If <tt>maxDepth == 0</tt>, no stack trace of the thread
* will be dumped.
* <p>
* When the Java virtual machine has no stack trace information
* about a thread or <tt>maxDepth == 0</tt>,
* the stack trace in the
* <tt>ThreadInfo</tt> object will be an empty array of
* <tt>StackTraceElement</tt>.
* <p>
* This method returns an array of the <tt>ThreadInfo</tt> objects,
* each is the thread information about the thread with the same index
* as in the <tt>ids</tt> array.
* If a thread of the given ID is not alive or does not exist,
* <tt>null</tt> 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 <tt>ThreadInfo</tt> is
* <tt>CompositeData</tt> with attributes as specified in
* {@link ThreadInfo#from ThreadInfo}.
*
* @param ids an array of thread IDs
* @param maxDepth the maximum number of entries in the stack trace
* to be dumped. <tt>Integer.MAX_VALUE</tt> 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.
*
* @throws IllegalArgumentException if <tt>maxDepth is negative</tt>.
* @throws IllegalArgumentException if any element in the input array
* <tt>ids</tt> is <tt><= 0</tt>.
* @throws java.lang.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.
*
* @return
* <tt>true</tt>
* if the Java virtual machine supports thread contention monitoring;
* <tt>false</tt> otherwise.
*/
public boolean isThreadContentionMonitoringSupported();
/**
* Tests if thread contention monitoring is enabled.
*
* @return <tt>true</tt> if thread contention monitoring is enabled;
* <tt>false</tt> otherwise.
*
* @throws java.lang.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.
*
* @param enable <tt>true</tt> to enable;
* <tt>false</tt> to disable.
*
* @throws java.lang.UnsupportedOperationException if the Java
* virtual machine does not support thread contention monitoring.
*
* @throws java.lang.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 precison 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 convenient 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; <tt>-1</tt> otherwise.
*
* @throws java.lang.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 precison but
* not necessarily nanoseconds accuracy.
*
* <p>
* This is a convenient 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; <tt>-1</tt> otherwise.
*
* @throws java.lang.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.
*
* <p>
* If the thread of the specified ID is not alive or does not exist,
* this method returns <tt>-1</tt>. If CPU time measurement
* is disabled, this method returns <tt>-1</tt>.
* 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;
* <tt>-1</tt> otherwise.
*
* @throws IllegalArgumentException if <tt>id <= 0 </tt>.
* @throws java.lang.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.
*
* <p>
* If the thread of the specified ID is not alive or does not exist,
* this method returns <tt>-1</tt>. If CPU time measurement
* is disabled, this method returns <tt>-1</tt>.
* 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;
* <tt>-1</tt> otherwise.
*
* @throws IllegalArgumentException if <tt>id <= 0 </tt>.
* @throws java.lang.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.
*
* @return
* <tt>true</tt>
* if the Java virtual machine supports CPU time
* measurement for any thread;
* <tt>false</tt> otherwise.
*/
public boolean isThreadCpuTimeSupported();
/**
* Tests if the Java virtual machine supports CPU time
* measurement for the current thread.
* This method returns <tt>true</tt> if {@link #isThreadCpuTimeSupported}
* returns <tt>true</tt>.
*
* @return
* <tt>true</tt>
* if the Java virtual machine supports CPU time
* measurement for current thread;
* <tt>false</tt> otherwise.
*/
public boolean isCurrentThreadCpuTimeSupported();
/**
* Tests if thread CPU time measurement is enabled.
*
* @return <tt>true</tt> if thread CPU time measurement is enabled;
* <tt>false</tt> otherwise.
*
* @throws java.lang.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.
*
* @param enable <tt>true</tt> to enable;
* <tt>false</tt> to disable.
*
* @throws java.lang.UnsupportedOperationException if the Java
* virtual machine does not support CPU time measurement for
* any threads nor for the current thread.
*
* @throws java.lang.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 {@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.
*
* @return an array of IDs of the threads that are monitor
* deadlocked, if any; <tt>null</tt> otherwise.
*
* @throws java.lang.SecurityException if a security manager
* exists and the caller does not have
* ManagementPermission("monitor").
*/
public long[] findMonitorDeadlockedThreads();
/**
* Resets the peak thread count to the current number of
* live threads.
*
* @throws java.lang.SecurityException if a security manager
* exists and the caller does not have
* ManagementPermission("control").
*
* @see #getPeakThreadCount
* @see #getThreadCount
*/
public void resetPeakThreadCount();
}
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