org.mortbay.util
Class ThreadPool

java.lang.Object
  |
  +--org.mortbay.util.ThreadPool

All Implemented Interfaces:

LifeCycle, java.io.Serializable

Direct Known Subclasses:

IO, ThreadedServer

public class ThreadPool

extends java.lang.Object

implements LifeCycle, java.io.Serializable

A pool of threads.

Avoids the expense of thread creation by pooling threads after their run methods exit for reuse.

If the maximum pool size is reached, jobs wait for a free thread. By default there is no maximum pool size. Idle threads timeout and terminate until the minimum number of threads are running.

This implementation uses the run(Object) method to place a job on a queue, which is read by the getJob(timeout) method. Derived implementations may specialize getJob(timeout) to obtain jobs from other sources without queing overheads.

Version:

$Id: ThreadPool.java,v 1.27.2.5 2004/03/30 10:28:42 gregwilkins Exp $

Author:

Juancarlo A???ez , Greg Wilkins

See Also:

Serialized Form

Nested Class Summary

static class

ThreadPool.PoolThread Pool Thread class.

Field Summary

static java.lang.String	__DAEMON
static java.lang.String	__PRIORITY

Constructor Summary

ThreadPool()

Method Summary

int	getIdleThreads() Get the number of idle threads in the pool.
int	getMaxIdleTimeMs() Get the maximum thread idle time.
int	getMaxThreads() Set the maximum number of threads.
int	getMinThreads() Get the minimum number of threads.
java.lang.String	getName()
java.lang.String	getPoolName()
int	getThreads() Get the number of threads in the pool.
int	getThreadsPriority() Get the priority of the pool threads.
boolean	isDaemon() Delegated to the named or anonymous Pool.
boolean	isStarted() Is the pool running jobs.
void	join()
void	run(java.lang.Object job) Run job.
void	setDaemon(boolean daemon) Delegated to the named or anonymous Pool.
void	setMaxIdleTimeMs(int maxIdleTimeMs) Set the maximum thread idle time.
void	setMaxStopTimeMs(int ms) Deprecated. maxIdleTime is used instead.
void	setMaxThreads(int maxThreads) Set the maximum number of threads.
void	setMinThreads(int minThreads) Set the minimum number of threads.
void	setName(java.lang.String name)
void	setPoolName(java.lang.String name) Set the Pool name.
void	setThreadsPriority(int priority) Set the priority of the pool threads.
void	shrink()
void	start() Start the LifeCycle.
void	stop() Stop the ThreadPool.

Methods inherited from class java.lang.Object

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

Field Detail

__DAEMON

public static final java.lang.String __DAEMON

See Also:

Constant Field Values

__PRIORITY

public static final java.lang.String __PRIORITY

See Also:

Constant Field Values

Constructor Detail

ThreadPool

public ThreadPool()

Method Detail

getName

public java.lang.String getName()

Returns:

The name of the ThreadPool.

setName

public void setName(java.lang.String name)

Parameters:

name - Name of the ThreadPool to use when naming Threads.

getPoolName

public java.lang.String getPoolName()

Returns:

Name of the Pool instance this ThreadPool uses or null for an anonymous private pool.

setPoolName

public void setPoolName(java.lang.String name)

Set the Pool name. All ThreadPool instances with the same Pool name will share the same Pool instance. Thus they will share the same max, min and available Threads. The field values of the first ThreadPool to call setPoolName with a specific name are used for the named Pool. Subsequent ThreadPools that join the name pool will loose their private values.

Parameters:

name - Name of the Pool instance this ThreadPool uses or null for an anonymous private pool.

isDaemon

public boolean isDaemon()

Delegated to the named or anonymous Pool.

setDaemon

public void setDaemon(boolean daemon)

Delegated to the named or anonymous Pool.

isStarted

public boolean isStarted()

Is the pool running jobs.

Specified by:

isStarted in interface LifeCycle

Returns:

True if start() has been called.

getThreads

public int getThreads()

Get the number of threads in the pool. Delegated to the named or anonymous Pool.

Returns:

Number of threads

See Also:

getIdleThreads()

getIdleThreads

public int getIdleThreads()

Get the number of idle threads in the pool. Delegated to the named or anonymous Pool.

Returns:

Number of threads

See Also:

getThreads()

getMinThreads

public int getMinThreads()

Get the minimum number of threads. Delegated to the named or anonymous Pool.

Returns:

minimum number of threads.

See Also:

setMinThreads(int)

setMinThreads

public void setMinThreads(int minThreads)

Set the minimum number of threads. Delegated to the named or anonymous Pool.

Parameters:

minThreads - minimum number of threads

See Also:

getMinThreads()

getMaxThreads

public int getMaxThreads()

Set the maximum number of threads. Delegated to the named or anonymous Pool.

Returns:

maximum number of threads.

See Also:

setMaxThreads(int)

setMaxThreads

public void setMaxThreads(int maxThreads)

Set the maximum number of threads. Delegated to the named or anonymous Pool.

Parameters:

maxThreads - maximum number of threads.

See Also:

getMaxThreads()

getMaxIdleTimeMs

public int getMaxIdleTimeMs()

Get the maximum thread idle time. Delegated to the named or anonymous Pool.

Returns:

Max idle time in ms.

See Also:

setMaxIdleTimeMs(int)

setMaxIdleTimeMs

public void setMaxIdleTimeMs(int maxIdleTimeMs)

Set the maximum thread idle time. Threads that are idle for longer than this period may be stopped. Delegated to the named or anonymous Pool.

Parameters:

maxIdleTimeMs - Max idle time in ms.

See Also:

getMaxIdleTimeMs()

getThreadsPriority

public int getThreadsPriority()

Get the priority of the pool threads.

Returns:

the priority of the pool threads.

setThreadsPriority

public void setThreadsPriority(int priority)

Set the priority of the pool threads.

Parameters:

priority - the new thread priority.

setMaxStopTimeMs

public void setMaxStopTimeMs(int ms)

Deprecated. maxIdleTime is used instead.

Set Max Read Time.

start

public void start()
           throws java.lang.Exception

Description copied from interface: LifeCycle

Start the LifeCycle.

Specified by:

start in interface LifeCycle

Throws:

java.lang.Exception - An arbitrary exception may be thrown.

stop

public void stop()
          throws java.lang.InterruptedException

Stop the ThreadPool. New jobs are no longer accepted,idle threads are interrupted and stopJob is called on active threads. The method then waits min(getMaxStopTimeMs(),getMaxIdleTimeMs()), for all jobs to stop, at which time killJob is called.

Specified by:

stop in interface LifeCycle

Throws:

java.lang.InterruptedException - Stopping a lifecycle is rarely atomic and may be interrupted by another thread. If this happens InterruptedException is throw and the component will be in an indeterminant state and should probably be discarded.

join

public void join()

shrink

public void shrink()
            throws java.lang.InterruptedException

java.lang.InterruptedException

run

public void run(java.lang.Object job)
         throws java.lang.InterruptedException

Run job. Give a job to the pool.

Parameters:

job - If the job is derived from Runnable, the run method is called, otherwise it is passed as the argument to the handle method.

java.lang.InterruptedException