org.apache.tomcat.util.threads
Class ThreadPool

java.lang.Object
  org.apache.tomcat.util.threads.ThreadPool

public class ThreadPool

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

Constructor Summary

ThreadPool()
Constructor.

Method Summary

void	addThread(java.lang.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()
java.lang.String	getName()
int	getSequence()
java.lang.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.
java.util.Enumeration	getThreads()
java.lang.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(java.lang.Thread t)
protected void	returnController(ThreadPool.ControlRunnable c) Returns the thread to the pool.
void	run(java.lang.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(java.lang.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()
java.lang.String	threadStatusString() Debug display of the stage of each thread.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_THREADS

public static final int MAX_THREADS

See Also:

Constant Field Values

MAX_THREADS_MIN

public static final int MAX_THREADS_MIN

See Also:

Constant Field Values

MAX_SPARE_THREADS

public static final int MAX_SPARE_THREADS

See Also:

Constant Field Values

MIN_SPARE_THREADS

public static final int MIN_SPARE_THREADS

See Also:

Constant Field Values

WORK_WAIT_TIMEOUT

public static final int WORK_WAIT_TIMEOUT

See Also:

Constant Field Values

pool

protected ThreadPool.ControlRunnable[] pool

monitor

protected ThreadPool.MonitorRunnable monitor

maxThreads

protected int maxThreads

minSpareThreads

protected int minSpareThreads

maxSpareThreads

protected int maxSpareThreads

currentThreadCount

protected int currentThreadCount

currentThreadsBusy

protected int currentThreadsBusy

stopThePool

protected boolean stopThePool

isDaemon

protected boolean isDaemon

threads

protected java.util.Hashtable threads

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

listeners

protected java.util.Vector listeners

name

protected java.lang.String name

Name of the threadpool

sequence

protected int sequence

Sequence.

threadPriority

protected int threadPriority

Thread priority.

Constructor Detail

ThreadPool

public ThreadPool()

Constructor.

Method Detail

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.

start

public void start()

getMonitor

public ThreadPool.MonitorRunnable getMonitor()

setThreadPriority

public void setThreadPriority(int threadPriority)

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

Parameters:

threadPriority - The new priority

Throws:

java.lang.IllegalArgumentException - If the specified priority is less than Thread.MIN_PRIORITY or more than Thread.MAX_PRIORITY

getThreadPriority

public int getThreadPriority()

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

Returns:

The priority

setMaxThreads

public void setMaxThreads(int maxThreads)

getMaxThreads

public int getMaxThreads()

setMinSpareThreads

public void setMinSpareThreads(int minSpareThreads)

getMinSpareThreads

public int getMinSpareThreads()

setMaxSpareThreads

public void setMaxSpareThreads(int maxSpareThreads)

getMaxSpareThreads

public int getMaxSpareThreads()

getCurrentThreadCount

public int getCurrentThreadCount()

getCurrentThreadsBusy

public int getCurrentThreadsBusy()

isDaemon

public boolean isDaemon()

getDebug

public static int getDebug()

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.

getDaemon

public boolean getDaemon()

setName

public void setName(java.lang.String name)

getName

public java.lang.String getName()

getSequence

public int getSequence()

incSequence

public int incSequence()

addThread

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

removeThread

public void removeThread(java.lang.Thread t)

addThreadPoolListener

public void addThreadPoolListener(ThreadPool.ThreadPoolListener tpl)

getThreads

public java.util.Enumeration getThreads()

run

public void run(java.lang.Runnable r)

runIt

public void runIt(ThreadPoolRunnable r)

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

shutdown

public void shutdown()

Stop the thread pool

checkSpareControllers

protected void checkSpareControllers()

Called by the monitor thread to harvest idle threads.

returnController

protected void returnController(ThreadPool.ControlRunnable c)

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

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.

adjustLimits

protected void adjustLimits()

openThreads

protected void openThreads(int toOpen)

Create missing threads.

Parameters:

toOpen - Total number of threads we'll have open

threadStatusString

public java.lang.String threadStatusString()

Debug display of the stage of each thread. The return is html style, for display in the console ( it can be easily parsed too ).

Returns:

The thread status display

getThreadStatus

public java.lang.String[] getThreadStatus()

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

getThreadParam

public java.lang.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