Package com.iplanet.services.util

Class ThreadPool

java.lang.Object

com.iplanet.services.util.ThreadPool

public final class ThreadPool
extends Object

ThreadPool is a generic thread pool that manages and recycles threads instead of creating them everytime some task needs to be run on a different thread. Thread pooling saves the virtual machine the work of creating brand new threads for every short-lived task. In addition, it minimizes overhead associated with getting a thread started and cleaning it up after it dies. By creating a pool of threads, a single thread from the pool can be reused any number of times for different tasks.

This reduces response time because a thread is already constructed and started and is simply waiting for its next task. This is particularly useful when using many short-lived tasks. This may not be useful for long-lived tasks.

In future, this class may be enhanced to provide support growing the size of the pool at runtime to facilitate dynamic tuning.

Constructor Summary

Constructors

Constructor	Description
ThreadPool(String poolName, int numThreads, boolean daemon, Debug debug)	Constructs a thread pool with the poolName and given number of threads.

Method Summary

Modifier and Type	Method	Description
void	destroy()	Destroys the thread pool.
String	getName()	Returns the name of this thread pool
void	run(Runnable task)	Runs the user-defined task.
void	stopIdleThreads()	Stops all the idle threads in the pool.
String	toString()	Returns the string representation of this thread pool that includes the name, size and the number of currently idle threads

Methods inherited from class java.lang.Object

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

Constructor Detail

ThreadPool

public ThreadPool(String poolName,
                  int numThreads,
                  boolean daemon,
                  Debug debug)
           throws IllegalArgumentException

Constructs a thread pool with the poolName and given number of threads.

Parameters:

poolName - name of the thread pool

numThreads - maximum number of threads in the thread pool.

daemon - if true, all threads created will be daemon threads. If false, all threads created will be non-daemon threads.

debug - Debug object to send debug messages to.

Throws:

IllegalArgumentException - if poolName is null

Method Detail

run

public final void run(Runnable task)
               throws InterruptedException

Runs the user-defined task. To enable better debugging or profiling capabilities, the task Runnable should implement toString() to intuitively identify the task.

Parameters:

task - the user-defined Runnable to be scheduled for execution on this thread pool

Throws:

InterruptedException - when the thread invoking run is interrupted.

stopIdleThreads

public final void stopIdleThreads()

Stops all the idle threads in the pool. Note that these stopped threads are no longer availble for future tasks because they are returned to underlying virtual machine. Also note that none of the active threads in the pool are stopped.

destroy

public final void destroy()

Destroys the thread pool. This stops all the threads, active and idle, in the pool and releases all resources.

toString

public String toString()

Returns the string representation of this thread pool that includes the name, size and the number of currently idle threads

Overrides:

toString in class Object

getName

public final String getName()

Returns the name of this thread pool