Package org.biojava.utils

Class SimpleThreadPool

java.lang.Object
org.biojava.utils.SimpleThreadPool
All Implemented Interfaces:
ThreadPool
public class SimpleThreadPool extends Object implements ThreadPool

SimpleThreadPool is a basic implementation of ThreadPool for use where we don't wish to introduce a dependency on a 3rd-party pool. In general, objects which require a pool should only use the interface and parameterize such that other implementations may be dropped in in place of this one, possibly using this one as a fallback.

This class offers a service for running Runnables using multiple threads, the number of which is specified in the constructor. Runnables are queued in a simple FIFO queue. The worker threads wait on the queue when it is empty and are notified when a new Runnable is submitted.

This implementation will prevent an application from exiting until stopThreads() is called unless the pool contains daemon threads.

Since:
1.3
Author:
Keith James

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected int
    priority
     
    protected org.biojava.utils.SimpleThreadPool.PooledThread[]
    threads
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    SimpleThreadPool()
    Creates a new SimpleThreadPool containing 4 non-daemon threads and starts them.
    SimpleThreadPool(int threadCount, boolean daemon)
    Creates a new SimpleThreadPool containing the specified number of threads and starts them.
    SimpleThreadPool(int threadCount, boolean daemon, int priority)
    Creates a new SimpleThreadPool containing the specified number of threads and starts them.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addRequest(Runnable task)
    addRequest requests that a Runnable be scheduled to be run by one of the threads in the pool.
    protected Runnable
    nextRequest()
    nextRequest gets the next Runnable from the queue.
    int
    requestsQueued()
    requestsQueued returns the number of Runnables currently queued.
    void
    startThreads()
    startThreads starts all the threads running and opens the pool to requests.
    void
    stopThreads()
    Waits for all working threads to return and then stops them.
    protected int
    threadsAlive()
    threadsAlive returns the number of threads currently alive.
    int
    threadsIdle()
    threadsIdle returns the number of threads currently waiting for work.
    int
    threadsWorking()
    threadsWorking returns the number of threads currently performing work.
    void
    waitForThreads()
    waitForThreads temporarily closes the pool to new requests until such time as the current request queue has been emptied and all running tasks completed.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • threads

      protected org.biojava.utils.SimpleThreadPool.PooledThread[] threads

    • priority

      protected int priority

  • Constructor Details

    • SimpleThreadPool

      public SimpleThreadPool()
      Creates a new SimpleThreadPool containing 4 non-daemon threads and starts them. The threads have priority Thread.NORM_PRIORITY. Because threads are non-deamon you will need to call stopThreads() to terminate them.

    • SimpleThreadPool

      public SimpleThreadPool(int threadCount, boolean daemon)
      Creates a new SimpleThreadPool containing the specified number of threads and starts them. The threads have priority Thread.NORM_PRIORITY.
      Parameters:
      threadCount - an int thread count.
      daemon - a boolean indicating whether the threads should be daemons. If threads are non-deamon you will need to call stopThreads() to terminate them.

    • SimpleThreadPool

      public SimpleThreadPool(int threadCount, boolean daemon, int priority)
      Creates a new SimpleThreadPool containing the specified number of threads and starts them.
      Parameters:
      threadCount - an int thread count.
      daemon - a boolean indicating whether the threads should be daemons. If threads are non-deamon you will need to call stopThreads() to terminate them.
      priority - an int priority for the threads.

  • Method Details

    • addRequest

      public void addRequest(Runnable task)
      Description copied from interface: ThreadPool
      addRequest requests that a Runnable be scheduled to be run by one of the threads in the pool.
      Specified by:
      addRequest in interface ThreadPool
      Parameters:
      task - a Runnable.

    • startThreads

      public void startThreads()
      Description copied from interface: ThreadPool
      startThreads starts all the threads running and opens the pool to requests.
      Specified by:
      startThreads in interface ThreadPool

    • stopThreads

      public void stopThreads()
      Waits for all working threads to return and then stops them. If the thread pool contains non-daemon threads you will have to call this method to make your program return.
      Specified by:
      stopThreads in interface ThreadPool
      Throws:
      IllegalStateException - if the pool is already stopped.

    • waitForThreads

      public void waitForThreads()
      Description copied from interface: ThreadPool
      waitForThreads temporarily closes the pool to new requests until such time as the current request queue has been emptied and all running tasks completed.
      Specified by:
      waitForThreads in interface ThreadPool

    • threadsWorking

      public int threadsWorking()
      threadsWorking returns the number of threads currently performing work.
      Returns:
      an int.

    • threadsIdle

      public int threadsIdle()
      threadsIdle returns the number of threads currently waiting for work.
      Returns:
      an int.

    • requestsQueued

      public int requestsQueued()
      requestsQueued returns the number of Runnables currently queued.
      Returns:
      an int.

    • threadsAlive

      protected int threadsAlive()
      threadsAlive returns the number of threads currently alive.
      Returns:
      an int.

    • nextRequest

      protected Runnable nextRequest()
      nextRequest gets the next Runnable from the queue. This method blocks if the queue is empty and the pool has not stopped. If the pool has stopped it returns null.
      Returns:
      a Runnable or null if the pool has been stopped.