com.portal.common

Class ThreadPool

java.lang.Object

java.lang.ThreadGroup

com.portal.common.ThreadPool

All Implemented Interfaces:

Thread.UncaughtExceptionHandler

public class ThreadPool
extends ThreadGroup

A ThreadPool is a group of threads that are generally pre-started and are re-used when finished. It is used to overcome performence issues with startup and shutdown of threads

Version:

%version: 3 % %date_modified: Tue Oct 23 15:59:35 2001 %

Author:

larrylf

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_THREADS
static int	DEFAULT_MIN_THREADS
static long	DEFAULT_THREAD_TIME

Constructor Summary

Constructors

Constructor and Description
ThreadPool() Instanciate a new ThreadPool using defaults.
ThreadPool(int minThreads, int maxThreads, long timeUnused) Instanciate a new ThreadPool with the specified minimum and maximum number of active threads.

Method Summary

Modifier and Type	Method and Description
void	runThis(Runnable item) Run a runnable in a pool thread.
void	runThis(Runnable item, int pri) Run a runnable in a pool thread.

Methods inherited from class java.lang.ThreadGroup

activeCount, activeGroupCount, allowThreadSuspension, checkAccess, destroy, enumerate, enumerate, enumerate, enumerate, getMaxPriority, getName, getParent, interrupt, isDaemon, isDestroyed, list, parentOf, resume, setDaemon, setMaxPriority, stop, suspend, toString, uncaughtException

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MIN_THREADS

public static int DEFAULT_MIN_THREADS

DEFAULT_MAX_THREADS

public static int DEFAULT_MAX_THREADS

DEFAULT_THREAD_TIME

public static long DEFAULT_THREAD_TIME

Constructor Detail

ThreadPool

public ThreadPool()

Instanciate a new ThreadPool using defaults.

ThreadPool

public ThreadPool(int minThreads,
                  int maxThreads,
                  long timeUnused)

Instanciate a new ThreadPool with the specified minimum and maximum number of active threads. The timeUnused parameter is used to terminate unused threads that may be hanging around to long.

Parameters:

minThreads - The minimum number of threads to keep in the pool Defaults to 0. THese are started immediatly (in another thread)

maxThreads - The maximum number of threads allowed. Tho pool will be allowed to grow to this many threads, if needed. Defaults to 20.

timeUnused - The amount of time (in ms) a thread is allowed to remain unused before being terminated. If 0, then threads will never die. Defaults to 0.

Method Detail

runThis

public void runThis(Runnable item)

Run a runnable in a pool thread. If all threads are busy, and less then the maximum threads have been created, then a new thread is created, and allocated to this runnable. Otherwise, it is queued up for the next available thread. NOTE: There are no enforced gurentees that a thread will become available. Thread pool threads should only be used for tasks that run for a while then die, rather then go forever, but this cannot be enforced.

Parameters:

item - A runnable item to run in the next thread

runThis

public void runThis(Runnable item,
                    int pri)

Run a runnable in a pool thread. If all threads are busy, and less then the maximum threads have been created, then a new thread is created, and allocated to this runnable. Otherwise, it is queued up for the next available thread. NOTE: There are no enforced gurentees that a thread will become available. Thread pool threads should only be used for tasks that run for a while then die, rather then go forever, but this cannot be enforced.

Parameters:

item - A runnable item to run in the next thread