ThreadPoolExecutor.DiscardOldestPolicy

AI-generated Key Takeaways

• ThreadPoolExecutor.DiscardOldestPolicy is a handler for rejected tasks in a ThreadPoolExecutor.

• It discards the oldest unhandled task and attempts to retry the current task.

• If the executor is shut down, the task is discarded instead of being retried.

• This policy is implemented by the rejectedExecution method, which handles the task rejection logic.

public static class ThreadPoolExecutor.DiscardOldestPolicy extends Object
implements RejectedExecutionHandler

A handler for rejected tasks that discards the oldest unhandled request and then retries execute, unless the executor is shut down, in which case the task is discarded.

Public Constructor Summary

DiscardOldestPolicy() Creates a DiscardOldestPolicy for the given executor.

Public Method Summary

void	rejectedExecution(Runnable r, ThreadPoolExecutor e) Obtains and ignores the next task that the executor would otherwise execute, if one is immediately available, and then retries execution of task r, unless the executor is shut down, in which case task r is instead discarded.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.util.concurrent.RejectedExecutionHandler

abstract void

rejectedExecution(Runnable r, ThreadPoolExecutor executor) Method that may be invoked by a ThreadPoolExecutor when execute cannot accept a task.

Public Constructors

public DiscardOldestPolicy ()

Creates a DiscardOldestPolicy for the given executor.

Public Methods

public void rejectedExecution (Runnable r, ThreadPoolExecutor e)

Obtains and ignores the next task that the executor would otherwise execute, if one is immediately available, and then retries execution of task r, unless the executor is shut down, in which case task r is instead discarded.

Parameters

r	the runnable task requested to be executed
e	the executor attempting to execute this task