org.biojava.utils

Class SimpleThreadPool

java.lang.Object

org.biojava.utils.SimpleThreadPool

All Implemented Interfaces:

ThreadPool

public class SimpleThreadPool
extends Object
implements ThreadPool

SimpleThreadPool is a basic implementation of ThreadPool for use where we don't wish to introduce a dependency on a 3rd-party pool. In general, objects which require a pool should only use the interface and parameterize such that other implementations may be dropped in in place of this one, possibly using this one as a fallback.

This class offers a service for running Runnables using multiple threads, the number of which is specified in the constructor. Runnables are queued in a simple FIFO queue. The worker threads wait on the queue when it is empty and are notified when a new Runnable is submitted.

This implementation will prevent an application from exiting until stopThreads() is called unless the pool contains daemon threads.

Since:

1.3

Author:

Keith James

Field Summary

Fields

Modifier and Type	Field and Description
protected int	priority
protected org.biojava.utils.SimpleThreadPool.PooledThread[]	threads

Constructor Summary

Constructors

Constructor and Description
SimpleThreadPool() Creates a new SimpleThreadPool containing 4 non-daemon threads and starts them.
SimpleThreadPool(int threadCount, boolean daemon) Creates a new SimpleThreadPool containing the specified number of threads and starts them.
SimpleThreadPool(int threadCount, boolean daemon, int priority) Creates a new SimpleThreadPool containing the specified number of threads and starts them.

Method Summary

Methods

Modifier and Type	Method and Description
void	addRequest(Runnable task) addRequest requests that a Runnable be scheduled to be run by one of the threads in the pool.
protected Runnable	nextRequest() nextRequest gets the next Runnable from the queue.
int	requestsQueued() requestsQueued returns the number of Runnables currently queued.
void	startThreads() startThreads starts all the threads running and opens the pool to requests.
void	stopThreads() Waits for all working threads to return and then stops them.
protected int	threadsAlive() threadsAlive returns the number of threads currently alive.
int	threadsIdle() threadsIdle returns the number of threads currently waiting for work.
int	threadsWorking() threadsWorking returns the number of threads currently performing work.
void	waitForThreads() waitForThreads temporarily closes the pool to new requests until such time as the current request queue has been emptied and all running tasks completed.

Methods inherited from class java.lang.Object

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

Field Detail

threads

protected org.biojava.utils.SimpleThreadPool.PooledThread[] threads

priority

protected int priority

Constructor Detail

SimpleThreadPool

public SimpleThreadPool()

Creates a new SimpleThreadPool containing 4 non-daemon threads and starts them. The threads have priority Thread.NORM_PRIORITY. Because threads are non-deamon you will need to call stopThreads() to terminate them.

SimpleThreadPool

public SimpleThreadPool(int threadCount,
                boolean daemon)

Creates a new SimpleThreadPool containing the specified number of threads and starts them. The threads have priority Thread.NORM_PRIORITY.

Parameters:

threadCount - an int thread count.

daemon - a boolean indicating whether the threads should be daemons. If threads are non-deamon you will need to call stopThreads() to terminate them.

SimpleThreadPool

public SimpleThreadPool(int threadCount,
                boolean daemon,
                int priority)

Creates a new SimpleThreadPool containing the specified number of threads and starts them.

Parameters:

threadCount - an int thread count.

daemon - a boolean indicating whether the threads should be daemons. If threads are non-deamon you will need to call stopThreads() to terminate them.

priority - an int priority for the threads.

Method Detail

addRequest

public void addRequest(Runnable task)

Description copied from interface: ThreadPool

addRequest requests that a Runnable be scheduled to be run by one of the threads in the pool.

Specified by:

addRequest in interface ThreadPool

Parameters:

task - a Runnable.

startThreads

public void startThreads()

Description copied from interface: ThreadPool

startThreads starts all the threads running and opens the pool to requests.

Specified by:

startThreads in interface ThreadPool

stopThreads

public void stopThreads()

Waits for all working threads to return and then stops them. If the thread pool contains non-daemon threads you will have to call this method to make your program return.

Specified by:

stopThreads in interface ThreadPool

Throws:

IllegalStateException - if the pool is already stopped.

waitForThreads

public void waitForThreads()

Description copied from interface: ThreadPool

waitForThreads temporarily closes the pool to new requests until such time as the current request queue has been emptied and all running tasks completed.

Specified by:

waitForThreads in interface ThreadPool

threadsWorking

public int threadsWorking()

threadsWorking returns the number of threads currently performing work.

Returns:

an int.

threadsIdle

public int threadsIdle()

threadsIdle returns the number of threads currently waiting for work.

Returns:

an int.

requestsQueued

public int requestsQueued()

requestsQueued returns the number of Runnables currently queued.

Returns:

an int.

threadsAlive

protected int threadsAlive()

threadsAlive returns the number of threads currently alive.

Returns:

an int.

nextRequest

protected Runnable nextRequest()

nextRequest gets the next Runnable from the queue. This method blocks if the queue is empty and the pool has not stopped. If the pool has stopped it returns null.

Returns:

a Runnable or null if the pool has been stopped.