java.lang.management
Class ThreadInfo

java.lang.Object
  java.lang.management.ThreadInfo

public class ThreadInfo
extends Object

Thread information. ThreadInfo contains the information about a thread including:

General thread information

• Thread ID.
• Name of the thread.

Execution information

• Thread state.
• The object upon which the thread is blocked waiting to enter a synchronization block or waiting to be notified in a Object.wait call.
• The ID of the thread that owns the object that the thread is blocked.
• Stack trace of the thread.

Synchronization statistics

• The number of times that the thread has blocked for synchronization or waited for notification.
• The accumulated elapsed time that the thread has blocked for synchronization or waited for notification since thread contention monitoring was enabled. Some Java virtual machine implementation may not support this. The ThreadMXBean.isThreadContentionMonitoringSupported() method can be used to determine if a Java virtual machine supports this.

This thread information class is designed for use in monitoring of the system, not for synchronization control.

MXBean Mapping

ThreadInfo is mapped to a CompositeData with attributes as specified in the from method.

Since:

1.5

See Also:

ThreadMXBean.isThreadContentionMonitoringSupported()

Method Summary

static ThreadInfo	from(CompositeData cd) Returns a ThreadInfo object represented by the given CompositeData.
long	getBlockedCount() Returns the total number of times that the thread associated with this ThreadInfo blocked to enter or reenter a monitor.
long	getBlockedTime() Returns the approximate accumulated elapsed time (in milliseconds) that the thread associated with this ThreadInfo has blocked to enter or reenter a monitor since thread contention monitoring is enabled.
String	getLockName() Returns the string representation of the monitor lock that the thread associated with this ThreadInfo is blocked to enter or waiting to be notified through the Object.wait method.
long	getLockOwnerId() Returns the ID of the thread which holds the monitor lock of an object on which the thread associated with this ThreadInfo is blocking.
String	getLockOwnerName() Returns the name of the thread which holds the monitor lock of an object on which the thread associated with this ThreadInfo is blocking.
StackTraceElement[]	getStackTrace() Returns the stack trace of the thread associated with this ThreadInfo.
long	getThreadId() Returns the ID of the thread associated with this ThreadInfo.
String	getThreadName() Returns the name of the thread associated with this ThreadInfo.
Thread.State	getThreadState() Returns the state of the thread associated with this ThreadInfo.
long	getWaitedCount() Returns the total number of times that the thread associated with this ThreadInfo waited for notification.
long	getWaitedTime() Returns the approximate accumulated elapsed time (in milliseconds) that the thread associated with this ThreadInfo has waited for notification since thread contention monitoring is enabled.
boolean	isInNative() Tests if the thread associated with this ThreadInfo is executing native code via the Java Native Interface (JNI).
boolean	isSuspended() Tests if the thread associated with this ThreadInfo is suspended.
String	toString() Returns a string representation of this thread info.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getThreadId

public long getThreadId()

Returns the ID of the thread associated with this ThreadInfo.

Returns:

the ID of the associated thread.

getThreadName

public String getThreadName()

Returns the name of the thread associated with this ThreadInfo.

Returns:

the name of the associated thread.

getThreadState

public Thread.State getThreadState()

Returns the state of the thread associated with this ThreadInfo.

Returns:

Thread.State of the associated thread.

getBlockedTime

public long getBlockedTime()

Returns the approximate accumulated elapsed time (in milliseconds) that the thread associated with this 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 BLOCKED state since thread contention monitoring was last enabled. This method returns -1 if thread contention monitoring is disabled.

The Java virtual machine may measure the time with a high resolution timer. This statistic is reset when the thread contention monitoring is reenabled.

Returns:

the approximate accumulated elapsed time in milliseconds that a thread entered the BLOCKED state; -1 if thread contention monitoring is disabled.

Throws:

UnsupportedOperationException - if the Java virtual machine does not support this operation.

See Also:

ThreadMXBean.isThreadContentionMonitoringSupported(), ThreadMXBean.setThreadContentionMonitoringEnabled(boolean)

getBlockedCount

public long getBlockedCount()

Returns the total number of times that the thread associated with this ThreadInfo blocked to enter or reenter a monitor. I.e. the number of times a thread has been in the BLOCKED state.

Returns:

the total number of times that the thread entered the BLOCKED state.

getWaitedTime

public long getWaitedTime()

Returns the approximate accumulated elapsed time (in milliseconds) that the thread associated with this ThreadInfo has waited for notification since thread contention monitoring is enabled. I.e. the total accumulated time the thread has been in the WAITING or TIMED_WAITING state since thread contention monitoring is enabled. This method returns -1 if thread contention monitoring is disabled.

The Java virtual machine may measure the time with a high resolution timer. This statistic is reset when the thread contention monitoring is reenabled.

Returns:

the approximate accumulated elapsed time in milliseconds that a thread has been in the WAITING or TIMED_WAITING state; -1 if thread contention monitoring is disabled.

Throws:

UnsupportedOperationException - if the Java virtual machine does not support this operation.

See Also:

ThreadMXBean.isThreadContentionMonitoringSupported(), ThreadMXBean.setThreadContentionMonitoringEnabled(boolean)

getWaitedCount

public long getWaitedCount()

Returns the total number of times that the thread associated with this ThreadInfo waited for notification. I.e. the number of times that a thread has been in the WAITING or TIMED_WAITING state.

Returns:

the total number of times that the thread was in the WAITING or TIMED_WAITING state.

getLockName

public String getLockName()

Returns the string representation of the monitor lock that the thread associated with this ThreadInfo is blocked to enter or waiting to be notified through the Object.wait method. The returned string representation of a monitor lock consists of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the identity hash code of the object. The returned string may not be unique depending on the implementation of the System.identityHashCode(java.lang.Object) method. This method returns a string equals to the value of:

 lock.getClass().getName() + '@' + Integer.toHexString(System.identityHashCode(lock))
 

where lock is the monitor lock object.

If the thread is not blocking to enter on any monitor object, or is not waiting on a monitor object for notification in a Object.wait call, this method returns null.

Returns:

the string representation of the monitor lock that the thread is blocking to enter or waiting to be notified through the Object.wait method if any; null otherwise.

getLockOwnerId

public long getLockOwnerId()

Returns the ID of the thread which holds the monitor lock of an object on which the thread associated with this ThreadInfo is blocking. This method will return -1 if this thread is not blocked or waiting on any monitor, or if the monitor lock is not held by any thread.

Returns:

the thread ID of the owner thread of the monitor lock of the object this thread is blocking on; -1 if this thread is not blocked or waiting on any monitor, or if the monitor lock is not held by any thread.

See Also:

getLockName()

getLockOwnerName

public String getLockOwnerName()

Returns the name of the thread which holds the monitor lock of an object on which the thread associated with this ThreadInfo is blocking. This method will return null if this thread is not blocked or waiting on any monitor, or if the monitor lock is not held by any thread.

Returns:

the name of the thread that holds the monitor lock of the object this thread is blocking on; null if this thread is not blocked or waiting on any monitor, or if the monitor lock is not held by any thread.

See Also:

getLockName()

getStackTrace

public StackTraceElement[] getStackTrace()

Returns the stack trace of the thread associated with this 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.

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 ThreadInfo is permitted to return a zero-length array from this method.

Returns:

an array of StackTraceElement objects of the thread.

isSuspended

public boolean isSuspended()

Tests if the thread associated with this ThreadInfo is suspended. This method returns true if Thread.suspend() has been called.

Returns:

true if the thread is suspended; false otherwise.

isInNative

public boolean isInNative()

Tests if the thread associated with this 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.

Returns:

true if the thread is executing native code; false otherwise.

toString

public String toString()

Returns a string representation of this thread info.

Overrides:

toString in class Object

Returns:

a string representation of this thread info.

from

public static ThreadInfo from(CompositeData cd)

Returns a ThreadInfo object represented by the given CompositeData. The given CompositeData must contain the following attributes:

Attribute Name

Type

threadId

java.lang.Long

threadName

java.lang.String

threadState

java.lang.String

suspended

java.lang.Boolean

inNative

java.lang.Boolean

blockedCount

java.lang.Long

blockedTime

java.lang.Long

waitedCount

java.lang.Long

waitedTime

java.lang.Long

lockName

java.lang.String

lockOwnerId

java.lang.Long

lockOwnerName

java.lang.String

stackTrace

javax.management.openmbean.CompositeData[]

Each element is a CompositeData representing StackTraceElement containing the following attributes:

Attribute Name	Type
className	java.lang.String
methodName	java.lang.String
fileName	java.lang.String
lineNumber	java.lang.Integer
nativeMethod	java.lang.Boolean

Parameters:

cd - CompositeData representing a ThreadInfo

Returns:

a ThreadInfo object represented by cd if cd is not null; null otherwise.

Throws:

IllegalArgumentException - if cd does not represent a ThreadInfo with the attributes described above.