Class ForkJoinWorkerThread

java.lang.Object

java.lang.Thread

java.util.concurrent.ForkJoinWorkerThread

All Implemented Interfaces:

Runnable

public class ForkJoinWorkerThread
extends Thread

A thread managed by a ForkJoinPool, which executes ForkJoinTasks. This class is subclassable solely for the sake of adding functionality -- there are no overridable methods dealing with scheduling or execution. However, you can override initialization and termination methods surrounding the main task processing loop. If you do create such a subclass, you will also need to supply a custom ForkJoinPool.ForkJoinWorkerThreadFactory to use it in a ForkJoinPool.

Since:

1.7

Nested Class Summary

Nested classes/interfaces declared in class Thread

Thread.Builder, Thread.State, Thread.UncaughtExceptionHandler

Modifier and Type	Class	Description
static interface	Thread.Builder	A builder for Thread and ThreadFactory objects.
static enum	Thread.State	A thread state.
static interface	Thread.UncaughtExceptionHandler	Interface for handlers invoked when a Thread abruptly terminates due to an uncaught exception.

Field Summary

Fields declared in class Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Modifier and Type	Field	Description
static final int	MAX_PRIORITY	The maximum priority that a thread can have.
static final int	MIN_PRIORITY	The minimum priority that a thread can have.
static final int	NORM_PRIORITY	The default priority that is assigned to a thread.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ForkJoinWorkerThread(ThreadGroup group, ForkJoinPool pool, boolean preserveThreadLocals)	Creates a ForkJoinWorkerThread operating in the given thread group and pool, and with the given policy for preserving ThreadLocals.
protected	ForkJoinWorkerThread(ForkJoinPool pool)	Creates a ForkJoinWorkerThread operating in the given pool.

Method Summary

Modifier and Type	Method	Description
ForkJoinPool	getPool()	Returns the pool hosting this thread.
int	getPoolIndex()	Returns the unique index number of this thread in its pool.
int	getQueuedTaskCount()	Returns a (non-negative) estimate of the number of tasks in the thread's queue.
protected void	onStart()	Initializes internal state after construction but before processing any tasks.
protected void	onTermination(Throwable exception)	Performs cleanup associated with termination of this worker thread.
void	run()	This method is required to be public, but should never be called explicitly.

Methods declared in class Thread

activeCount, checkAccess, clone, currentThread, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, isVirtual, join, join, join, join, ofPlatform, ofVirtual, onSpinWait, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, sleep, start, startVirtualThread, threadId, toString, yield

Modifier and Type	Method	Description
static int	activeCount()	Returns an estimate of the number of live platform threads in the current thread's thread group and its subgroups.
final void	checkAccess()	Deprecated, for removal: This API element is subject to removal in a future version. This method originally determined if the currently running thread had permission to modify this thread.
protected Object	clone()	Throws CloneNotSupportedException as a Thread can not be meaningfully cloned.
static Thread	currentThread()	Returns the Thread object for the current thread.
static void	dumpStack()	Prints a stack trace of the current thread to the standard error stream.
static int	enumerate(Thread[] tarray)	Copies into the specified array every live platform thread in the current thread's thread group and its subgroups.
static Map<Thread, StackTraceElement[]>	getAllStackTraces()	Returns a map of stack traces for all live platform threads.
ClassLoader	getContextClassLoader()	Returns the context ClassLoader for this thread.
static Thread.UncaughtExceptionHandler	getDefaultUncaughtExceptionHandler()	Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception.
long	getId()	Deprecated. This method is not final and may be overridden to return a value that is not the thread ID.
final String	getName()	Returns this thread's name.
final int	getPriority()	Returns this thread's priority.
StackTraceElement[]	getStackTrace()	Returns an array of stack trace elements representing the stack dump of this thread.
Thread.State	getState()	Returns the state of this thread.
final ThreadGroup	getThreadGroup()	Returns the thread's thread group or null if the thread has terminated.
Thread.UncaughtExceptionHandler	getUncaughtExceptionHandler()	Returns the handler invoked when this thread abruptly terminates due to an uncaught exception.
static boolean	holdsLock(Object obj)	Returns true if and only if the current thread holds the monitor lock on the specified object.
void	interrupt()	Interrupts this thread.
static boolean	interrupted()	Tests whether the current thread has been interrupted.
final boolean	isAlive()	Tests if this thread is alive.
final boolean	isDaemon()	Tests if this thread is a daemon thread.
boolean	isInterrupted()	Tests whether this thread has been interrupted.
final boolean	isVirtual()	Returns true if this thread is a virtual thread.
final void	join()	Waits for this thread to terminate.
final void	join(long millis)	Waits at most millis milliseconds for this thread to terminate.
final void	join(long millis, int nanos)	Waits at most millis milliseconds plus nanos nanoseconds for this thread to terminate.
final boolean	join(Duration duration)	Waits for this thread to terminate for up to the given waiting duration.
static Thread.Builder.OfPlatform	ofPlatform()	Returns a builder for creating a platform Thread or ThreadFactory that creates platform threads.
static Thread.Builder.OfVirtual	ofVirtual()	Returns a builder for creating a virtual Thread or ThreadFactory that creates virtual threads.
static void	onSpinWait()	Indicates that the caller is momentarily unable to progress, until the occurrence of one or more actions on the part of other activities.
void	setContextClassLoader(ClassLoader cl)	Sets the context ClassLoader for this thread.
final void	setDaemon(boolean on)	Marks this thread as either a daemon or non-daemon thread.
static void	setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler ueh)	Set the default handler invoked when a thread abruptly terminates due to an uncaught exception, and no other handler has been defined for that thread.
final void	setName(String name)	Changes the name of this thread to be equal to the argument name.
final void	setPriority(int newPriority)	Changes the priority of this thread.
void	setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler ueh)	Set the handler invoked when this thread abruptly terminates due to an uncaught exception.
static void	sleep(long millis)	Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers.
static void	sleep(long millis, int nanos)	Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds plus the specified number of nanoseconds, subject to the precision and accuracy of system timers and schedulers.
static void	sleep(Duration duration)	Causes the currently executing thread to sleep (temporarily cease execution) for the specified duration, subject to the precision and accuracy of system timers and schedulers.
void	start()	Schedules this thread to begin execution.
static Thread	startVirtualThread(Runnable task)	Creates a virtual thread to execute a task and schedules it to execute.
final long	threadId()	Returns the identifier of this Thread.
String	toString()	Returns a string representation of this thread.
static void	yield()	A hint to the scheduler that the current thread is willing to yield its current use of a processor.

Methods declared in class Object

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

Modifier and Type	Method	Description
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

ForkJoinWorkerThread

protected ForkJoinWorkerThread(ThreadGroup group,
 ForkJoinPool pool,
 boolean preserveThreadLocals)

Creates a ForkJoinWorkerThread operating in the given thread group and pool, and with the given policy for preserving ThreadLocals.

Parameters:

group - if non-null, the thread group for this thread. Otherwise, the thread group is set to the current thread's thread group.

pool - the pool this thread works in

preserveThreadLocals - if true, always preserve the values of ThreadLocal variables across tasks; otherwise they may be cleared.

Throws:

NullPointerException - if pool is null

Since:

19

ForkJoinWorkerThread

protected ForkJoinWorkerThread(ForkJoinPool pool)

Creates a ForkJoinWorkerThread operating in the given pool.

Parameters:

pool - the pool this thread works in

Throws:

NullPointerException - if pool is null

Method Details

getPool

public ForkJoinPool getPool()

Returns the pool hosting this thread.

Returns:

the pool

getPoolIndex

public int getPoolIndex()

Returns the unique index number of this thread in its pool. The returned value ranges from zero to the maximum number of threads (minus one) that may exist in the pool, and does not change during the lifetime of the thread. This method may be useful for applications that track status or collect results per-worker-thread rather than per-task.

Returns:

the index number

getQueuedTaskCount

public int getQueuedTaskCount()

Returns a (non-negative) estimate of the number of tasks in the thread's queue.

Returns:

a (non-negative) estimate of the number of tasks in the thread's queue

Since:

20

See Also:

• ForkJoinPool.getQueuedTaskCount()

onStart

protected void onStart()

Initializes internal state after construction but before processing any tasks. If you override this method, you must invoke super.onStart() at the beginning of the method. Initialization requires care: Most fields must have legal default values, to ensure that attempted accesses from other threads work correctly even before this thread starts processing tasks.

onTermination

protected void onTermination(Throwable exception)

Performs cleanup associated with termination of this worker thread. If you override this method, you must invoke super.onTermination at the end of the overridden method.

Parameters:

exception - the exception causing this thread to abort due to an unrecoverable error, or null if completed normally

run

public void run()

This method is required to be public, but should never be called explicitly. It performs the main run loop to execute ForkJoinTasks.

Specified by:

run in interface Runnable

Overrides:

run in class Thread