org.jboss.util.threadpool

Class MinPooledExecutor

java.lang.Object

java.util.concurrent.AbstractExecutorService

java.util.concurrent.ThreadPoolExecutor

org.jboss.util.threadpool.MinPooledExecutor

All Implemented Interfaces:

java.util.concurrent.Executor, java.util.concurrent.ExecutorService

public class MinPooledExecutor
extends java.util.concurrent.ThreadPoolExecutor

A pooled executor where the minimum pool size threads are kept alive. This is needed in order for the waitWhenBlocked option to work because of a race condition inside the Executor. The race condition goes something like: RT - Requesting Thread wanting to use the pool LT - Last Thread in the pool RT: Check there are enough free threads to process, yes LT is there, so no need to create a new thread. LT: Times out on the keep alive, LT is destroyed. RT: Try to execute, blocks because there are no available threads. In fact, the pool is now empty which the executor mistakenly inteprets as all of them being in use. Doug Lea says he isn't going to fix. In fact, the version in j2se 1.5 doesn't have this option. In order for this to work, the min pool size must be > 0.

Version:

$Revision$

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.ThreadPoolExecutor

java.util.concurrent.ThreadPoolExecutor.AbortPolicy, java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy, java.util.concurrent.ThreadPoolExecutor.DiscardOldestPolicy, java.util.concurrent.ThreadPoolExecutor.DiscardPolicy

Field Summary

Fields

Modifier and Type	Field and Description
protected int	keepAliveSize The number of threads to keep alive threads

Constructor Summary

Constructors

Constructor and Description
MinPooledExecutor(java.util.concurrent.BlockingQueue queue, int poolSize) Construct a new executor
MinPooledExecutor(int poolSize) Construct a new executor

Method Summary

Modifier and Type	Method and Description
int	getKeepAliveSize()
void	setKeepAliveSize(int keepAliveSize)

Methods inherited from class java.util.concurrent.ThreadPoolExecutor

afterExecute, allowCoreThreadTimeOut, allowsCoreThreadTimeOut, awaitTermination, beforeExecute, execute, finalize, getActiveCount, getCompletedTaskCount, getCorePoolSize, getKeepAliveTime, getLargestPoolSize, getMaximumPoolSize, getPoolSize, getQueue, getRejectedExecutionHandler, getTaskCount, getThreadFactory, isShutdown, isTerminated, isTerminating, prestartAllCoreThreads, prestartCoreThread, purge, remove, setCorePoolSize, setKeepAliveTime, setMaximumPoolSize, setRejectedExecutionHandler, setThreadFactory, shutdown, shutdownNow, terminated, toString

Methods inherited from class java.util.concurrent.AbstractExecutorService

invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor, submit, submit, submit

Methods inherited from class java.lang.Object

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

Field Detail

keepAliveSize

protected int keepAliveSize

The number of threads to keep alive threads

Constructor Detail

MinPooledExecutor

public MinPooledExecutor(int poolSize)

Construct a new executor

Parameters:

poolSize - the maximum pool size

MinPooledExecutor

public MinPooledExecutor(java.util.concurrent.BlockingQueue queue,
                         int poolSize)

Construct a new executor

Parameters:

queue - the queue for any requests

poolSize - the maximum pool size

Method Detail

getKeepAliveSize

public int getKeepAliveSize()

Returns:

the number of threads to keep alive

setKeepAliveSize

public void setKeepAliveSize(int keepAliveSize)

Parameters:

keepAliveSize - the number of threads to keep alive