org.openqa.jetty.util

Class ThreadPool

java.lang.Object

org.openqa.jetty.util.ThreadPool

All Implemented Interfaces:

Serializable, LifeCycle

Direct Known Subclasses:

IO, SocketChannelListener, ThreadedServer

public class ThreadPool
extends Object
implements LifeCycle, 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. 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 1.41 2005/08/13 00:01:28 gregwilkins Exp $

Author:

Juancarlo A�ez , Greg Wilkins

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ThreadPool.PoolThread Pool Thread class.

Field Summary

Fields

Modifier and Type	Field and Description
static String	__DAEMON
static String	__PRIORITY

Constructor Summary

Constructors

Constructor and Description
ThreadPool()

Method Summary

Methods

Modifier and Type	Method and Description
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.
String	getName()
String	getPoolName() Deprecated. use getName()
int	getThreads() Get the number of threads in the pool.
int	getThreadsPriority() Get the priority of the pool threads.
protected void	handle(Object job) Handle a job.
boolean	isDaemon() Delegated to the named or anonymous Pool.
boolean	isStarted() Is the pool running jobs.
void	join()
void	run(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(String name) Set the Pool name.
void	setPoolName(String name) Deprecated. use setName(String)
void	setThreadsPriority(int priority) Set the priority of the pool threads.
void	shrink()
void	start() Start the LifeCycle.
void	stop() Stop the ThreadPool.
protected void	stopJob(Thread thread, Object job) Stop a Job.

Methods inherited from class java.lang.Object

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

Field Detail

__DAEMON

public static final String __DAEMON

See Also:

Constant Field Values

__PRIORITY

public static final String __PRIORITY

See Also:

Constant Field Values

Constructor Detail

ThreadPool

public ThreadPool()

Method Detail

getName

public String getName()

Returns:

The name of the ThreadPool.

setName

public void setName(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.

getPoolName

public String getPoolName()

Deprecated. use getName()

setPoolName

public void setPoolName(String name)

Deprecated. use setName(String)

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 Exception

Description copied from interface: LifeCycle

Start the LifeCycle.

Specified by:

start in interface LifeCycle

Throws:

Exception - An arbitrary exception may be thrown.

stop

public void stop()
          throws 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:

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 InterruptedException

Throws:

InterruptedException

run

public void run(Object job)
         throws 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.

Throws:

InterruptedException

handle

protected void handle(Object job)
               throws InterruptedException

Handle a job. Called by the allocated thread to handle a job. If the job is a Runnable, it's run method is called. Otherwise this method needs to be specialized by a derived class to provide specific handling.

Parameters:

job - The job to execute.

Throws:

InterruptedException

stopJob

protected void stopJob(Thread thread,
           Object job)

Stop a Job. This method is called by the Pool if a job needs to be stopped. The default implementation does nothing and should be extended by a derived thread pool class if special action is required.

Parameters:

thread - The thread allocated to the job, or null if no thread allocated.

job - The job object passed to run.