A simple thread pool

Abstract: A simple thread pool

</ Td> </ tr> <tr> <td height="35" valign="top" class="ArticleTeitle"> this code from the "java game programming," Beijing hope that the electronic publishing. David Brackeen the Qiuzhong Pan translation. Thread Pool entry code. Finishing head.
Import java.util.LinkedList;

Public class ThreadPool extends ThreadGroup (/ / thread as a group to achieve thread pool, innovative

<table Width="682" height="27" border="0"> <tr> <td width="407"> private boolean isAlive; / / this thread pool is activated
Private LinkedList taskQueue; / / storage tasks linked list
Private int threadID; / / thread pool threads of
Private static int threadPoolID; / / credited to the number of examples of a number of objects Thread Pool

/ **
The creation of a new thread pool.
@ Param numThreads pool of threads.
* /
Public ThreadPool (int numThreads) (
Super ( "ThreadPool-" + (threadPoolID ++));
SetDaemon (true);

IsAlive = true;

TaskQueue = new LinkedList ();
For (int i = 0; i New PooledThread (). Start ();// start numThreads threads for the implementation of the tasks in the linked list
)
)
</ Td> <td width="251"> </ td> </ tr> </ table>

Public synchronized void runTask (Runnable task) (/ / add to the linked list of the measures
If (! IsAlive) (
Throw new IllegalStateException ();
)
If (task! = Null) (
TaskQueue.add (task); / / add tasks
Notify ();// notice waiting threads
)

)

Protected synchronized Runnable getTask () / / from the linked list of tasks
Throws InterruptedException
(
While (taskQueue.size () == 0) (
If (! IsAlive) (
Return null;
)
Listless wait ();// If no task awaiting
)
Return (Runnable) taskQueue.removeFirst ();// out tasks
)

/ **
Close this thread pool and to return immediately. Stop all threads, not wait for the performance of any task.
* /
Public synchronized void close () (
If (isAlive) (
IsAlive = false;
TaskQueue.clear ();
Interrupt ();
)
)

/ **
Close this thread pool, and wait for the completion of all the running thread, for the performance of any task.
* /
Public void join () (
/ / Notify all waiting for the thread, the thread is no longer activities
Synchronized (this) (
IsAlive = false;
NotifyAll ();
)

/ / Wait for the completion of all threads
Thread [] threads = new Thread [activeCount ()];
Int count = enumerate (threads);
For (int i = 0; i Try (
[I] threads. Join ();
)
Catch (InterruptedException ex) ()
)
)

/ **
PooledThread is in a thread pool threads, used to run tasks (Runnables).
* /
Private class PooledThread extends Thread (/ / private, can be an example of the internal

Public PooledThread () (
Super (ThreadPool.this,
"PooledThread-" + (threadID ++));
)

Public void run () (/ / thread at the start of the implementation methods
While (! IsInterrupted ()) (/ / the key thread pool, the pool every thread as long as no interruption, recycling mandate

/ / Get a task to run
Runnable task = null;
Try (
Task = getTask ();// may need to wait
)
Catch (InterruptedException ex) ()

/ / If getTask () returned null or was interrupted,
/ / Close this thread by returning.
If (task == null) (
Return;
)

/ / Run the task, and eat any exceptions it throws
Try (
Task.run ();
)
Catch (Throwable t) (
UncaughtException (this, t);
) / / Task disposed of
) / / Thread to continue this cycle, or wait for the implementation of tasks.
)
)
)

Following is the test procedure:
(Public class ThreadPoolTest

Public static void main (String [] args) (
If (args.length! = 2) (
System.out.println ( "Tests the ThreadPool task.");
System.out.println (
"Usage: java ThreadPoolTest numTasks numThreads");
System.out.println (
"NumTasks - integer: number of task to run.");
System.out.println (
"NumThreads - integer: number of threads" +
"In the thread pool.");
Return;
)
Int numTasks = Integer.parseInt (args [0 ]);// need to run several tasks
Int numThreads = Integer.parseInt (args [1 ]);// thread pool launched several threads

/ / Create the thread pool
ThreadPool threadPool = new ThreadPool (numThreads); / / generate the thread pool, start thread pool thread

/ / Run example tasks
For (int i = 0; i ThreadPool.runTask (createTask (i ));// mandate to increase the pool thread
)

/ / Closing pool and wait for the completion of all tasks.
ThreadPool.join ();
)

/ **
Create simple task.
* /
Private static Runnable createTask (final int taskID) (
Return new Runnable () (
Public void run () (
System.out.println ( "Task" taskID + + ": start");

/ / Simulate a long-running task
Try (
Thread.sleep (500);
)
Catch (InterruptedException ex) ()

System.out.println ( "Task" taskID + + ": end");
)
);
)

)
Run:

C: \ java> java ThreadPoolTest 8 4
Task 0: start
Task 1: start
Task 2: start
Task 3: start
Task 0: end
Task 4: start
Task 2: end
Task 5: start
Task 3: end
Task 6: start
Task 1: end
Task 7: start
Task 4: end
Task 5: end
Task 6: end
Task 7: end

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