org.apache.tomcat.util.threads

Class ThreadPool

public class ThreadPool extends Object

A thread pool that is trying to copy the apache process management. Should we remove this in favor of Doug Lea's thread package?

Author: Gal Shachor Yoav Shapira

Nested Class Summary
static class	ThreadPool.ControlRunnable A Thread object that executes various actions ( ThreadPoolRunnable ) under control of ThreadPool
static class	ThreadPool.MonitorRunnable Periodically execute an action - cleanup in this case
static interface	ThreadPool.ThreadPoolListener Interface to allow applications to be notified when a threads are created and stopped.

Field Summary
protected int	currentThreadCount
protected int	currentThreadsBusy
protected boolean	isDaemon
protected Vector	listeners
protected int	maxSpareThreads
protected int	maxThreads
protected int	minSpareThreads
protected ThreadPool.MonitorRunnable	monitor
static int	MAX_SPARE_THREADS
static int	MAX_THREADS
static int	MAX_THREADS_MIN
static int	MIN_SPARE_THREADS
protected String	name Name of the threadpool
protected ThreadPool.ControlRunnable[]	pool
protected int	sequence Sequence.
protected boolean	stopThePool
protected int	threadPriority Thread priority.
protected Hashtable	threads The threads that are part of the pool.
static int	WORK_WAIT_TIMEOUT

Constructor Summary
	ThreadPool() Constructor.

Method Summary
void	addThread(Thread t, ThreadPool.ControlRunnable cr)
void	addThreadPoolListener(ThreadPool.ThreadPoolListener tpl)
protected void	adjustLimits()
protected void	checkSpareControllers() Called by the monitor thread to harvest idle threads.
static ThreadPool	createThreadPool(boolean jmx) Create a ThreadPool instance.
int	getCurrentThreadCount()
int	getCurrentThreadsBusy()
boolean	getDaemon()
static int	getDebug()
int	getMaxSpareThreads()
int	getMaxThreads()
int	getMinSpareThreads()
ThreadPool.MonitorRunnable	getMonitor()
String	getName()
int	getSequence()
String[]	getThreadParam() Return an array with the current "param" ( XXX better name ?
int	getThreadPriority() Returns the priority level of current and future threads in this pool.
Enumeration	getThreads()
String[]	getThreadStatus() Return an array with the status of each thread.
int	incSequence()
boolean	isDaemon()
protected void	notifyThreadEnd(ThreadPool.ControlRunnable c) Inform the pool that the specific thread finish.
protected void	openThreads(int toOpen) Create missing threads.
void	removeThread(Thread t)
protected void	returnController(ThreadPool.ControlRunnable c) Returns the thread to the pool.
void	run(Runnable r)
void	runIt(ThreadPoolRunnable r) Executes a given Runnable on a thread in the pool, block if needed.
void	setDaemon(boolean b) The default is true - the created threads will be in daemon mode.
void	setMaxSpareThreads(int maxSpareThreads)
void	setMaxThreads(int maxThreads)
void	setMinSpareThreads(int minSpareThreads)
void	setName(String name)
void	setThreadPriority(int threadPriority) Sets the thread priority for current and future threads in this pool.
void	shutdown() Stop the thread pool
void	start()
String	threadStatusString() Debug display of the stage of each thread.

Field Detail

monitor

protected ThreadPool.MonitorRunnable monitor

MAX_SPARE_THREADS

public static final int MAX_SPARE_THREADS

MIN_SPARE_THREADS

public static final int MIN_SPARE_THREADS

name

protected String name

Name of the threadpool

pool

protected ThreadPool.ControlRunnable[] pool

threadPriority

protected int threadPriority

Thread priority.

threads

protected Hashtable threads

The threads that are part of the pool. Key is Thread, value is the ControlRunnable

WORK_WAIT_TIMEOUT

public static final int WORK_WAIT_TIMEOUT

Method Detail

addThread

public void addThread(Thread t, ThreadPool.ControlRunnable cr)

addThreadPoolListener

public void addThreadPoolListener(ThreadPool.ThreadPoolListener tpl)

checkSpareControllers

protected void checkSpareControllers()

Called by the monitor thread to harvest idle threads.

createThreadPool

public static ThreadPool createThreadPool(boolean jmx)

Create a ThreadPool instance.

Parameters: jmx UNUSED

Returns: ThreadPool instance. If JMX support is requested, you need to call register() in order to set a name.

getMonitor

public ThreadPool.MonitorRunnable getMonitor()

getThreadParam

public String[] getThreadParam()

Return an array with the current "param" ( XXX better name ? ) of each thread. This is typically the last request.

Returns: The params of all threads

getThreadPriority

public int getThreadPriority()

Returns the priority level of current and future threads in this pool.

Returns: The priority

Return an array with the status of each thread. The status indicates the current request processing stage ( for tomcat ) or whatever the thread is doing ( if the application using TP provide this info )

Returns: The status of all threads

incSequence

public int incSequence()

isDaemon

public boolean isDaemon()

notifyThreadEnd

protected void notifyThreadEnd(ThreadPool.ControlRunnable c)

Inform the pool that the specific thread finish. Called by the ControlRunnable.run() when the runnable throws an exception.

openThreads

protected void openThreads(int toOpen)

Create missing threads.

Parameters: toOpen Total number of threads we'll have open

removeThread

public void removeThread(Thread t)

returnController

protected void returnController(ThreadPool.ControlRunnable c)

Returns the thread to the pool. Called by threads as they are becoming idel.

run

public void run(Runnable r)

runIt

public void runIt(ThreadPoolRunnable r)

Executes a given Runnable on a thread in the pool, block if needed.

setDaemon

public void setDaemon(boolean b)

The default is true - the created threads will be in daemon mode. If set to false, the control thread will not be daemon - and will keep the process alive.

setMaxSpareThreads

public void setMaxSpareThreads(int maxSpareThreads)

setMaxThreads

public void setMaxThreads(int maxThreads)

setMinSpareThreads

public void setMinSpareThreads(int minSpareThreads)

setName

public void setName(String name)

setThreadPriority

public void setThreadPriority(int threadPriority)

Sets the thread priority for current and future threads in this pool.

Parameters: threadPriority The new priority

Throws: IllegalArgumentException If the specified priority is less than Thread.MIN_PRIORITY or more than Thread.MAX_PRIORITY

Returns: The thread status display