public ThreadPoolExecutor(int corePoolSize,
    int maximumPoolSize,
    long keepAliveTime,
    TimeUnit unit,
    BlockingQueue<Runnable> workQueue) 
{
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
             Executors.defaultThreadFactory(), defaultHandler);
}

Creates a new ThreadPoolExecutor with the given initial parameters and default thread factory and handler. It may be more convenient to use one of the Executors factory methods instead of this general purpose constructor.

Parameters:

corePoolSize - the number of threads to keep in the pool, even if they are idle.

maximumPoolSize - the maximum number of threads to allow in the pool.

keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.

unit - the time unit for the keepAliveTime argument.

workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.

Throws:

IllegalArgumentException - if corePoolSize, or keepAliveTime less than zero, or if maximumPoolSize less than or equal to zero, or if corePoolSize greater than maximumPoolSize.

NullPointerException - if workQueue is null

 public ThreadPoolExecutor(int corePoolSize,
    int maximumPoolSize,
    long keepAliveTime,
    TimeUnit unit,
    BlockingQueue<Runnable> workQueue,
    ThreadFactory threadFactory) 
{
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
             threadFactory, defaultHandler);
}

Creates a new ThreadPoolExecutor with the given initial parameters.

Parameters:

corePoolSize - the number of threads to keep in the pool, even if they are idle.

maximumPoolSize - the maximum number of threads to allow in the pool.

keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.

unit - the time unit for the keepAliveTime argument.

workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.

threadFactory - the factory to use when the executor creates a new thread.

Throws:

IllegalArgumentException - if corePoolSize, or keepAliveTime less than zero, or if maximumPoolSize less than or equal to zero, or if corePoolSize greater than maximumPoolSize.

NullPointerException - if workQueue or threadFactory are null.

 public ThreadPoolExecutor(int corePoolSize,
    int maximumPoolSize,
    long keepAliveTime,
    TimeUnit unit,
    BlockingQueue<Runnable> workQueue,
    RejectedExecutionHandler handler) 
{
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
             Executors.defaultThreadFactory(), handler);
}

Creates a new ThreadPoolExecutor with the given initial parameters.

Parameters:

corePoolSize - the number of threads to keep in the pool, even if they are idle.

maximumPoolSize - the maximum number of threads to allow in the pool.

keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.

unit - the time unit for the keepAliveTime argument.

workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.

handler - the handler to use when execution is blocked because the thread bounds and queue capacities are reached.

Throws:

IllegalArgumentException - if corePoolSize, or keepAliveTime less than zero, or if maximumPoolSize less than or equal to zero, or if corePoolSize greater than maximumPoolSize.

NullPointerException - if workQueue or handler are null.

 public ThreadPoolExecutor(int corePoolSize,
    int maximumPoolSize,
    long keepAliveTime,
    TimeUnit unit,
    BlockingQueue<Runnable> workQueue,
    ThreadFactory threadFactory,
    RejectedExecutionHandler handler) 
{
        if (corePoolSize <  0 ||
            maximumPoolSize < = 0 ||
            maximumPoolSize <  corePoolSize ||
            keepAliveTime <  0)
            throw new IllegalArgumentException();
        if (workQueue == null || threadFactory == null || handler == null)
            throw new NullPointerException();
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
}

Creates a new ThreadPoolExecutor with the given initial parameters.

Parameters:

corePoolSize - the number of threads to keep in the pool, even if they are idle.

maximumPoolSize - the maximum number of threads to allow in the pool.

keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.

unit - the time unit for the keepAliveTime argument.

workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.

threadFactory - the factory to use when the executor creates a new thread.

handler - the handler to use when execution is blocked because the thread bounds and queue capacities are reached.

Throws:

IllegalArgumentException - if corePoolSize, or keepAliveTime less than zero, or if maximumPoolSize less than or equal to zero, or if corePoolSize greater than maximumPoolSize.

NullPointerException - if workQueue or threadFactory or handler are null.

 protected  void afterExecute(Runnable r,
    Throwable t) 
{

}

Method invoked upon completion of execution of the given Runnable. This method is invoked by the thread that executed the task. If non-null, the Throwable is the uncaught exception that caused execution to terminate abruptly. Note: To properly nest multiple overridings, subclasses should generally invoke super.afterExecute at the beginning of this method.

 public boolean awaitTermination(long timeout,
    TimeUnit unit) throws InterruptedException 
{
        long nanos = unit.toNanos(timeout);
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            for (;;) {
                if (runState == TERMINATED) 
                    return true;
                if (nanos < = 0)
                    return false;
                nanos = termination.awaitNanos(nanos);
            }
        } finally {
            mainLock.unlock();
        }
}

 protected  void beforeExecute(Thread t,
    Runnable r) 
{

}

Method invoked prior to executing the given Runnable in the given thread. This method is invoked by thread t that will execute task r, and may be used to re-initialize ThreadLocals, or to perform logging. Note: To properly nest multiple overridings, subclasses should generally invoke super.beforeExecute at the end of this method.

 public  void execute(Runnable command) 
{
        if (command == null)
            throw new NullPointerException();
        for (;;) {
            if (runState != RUNNING) {
                reject(command);
                return;
            }
            if (poolSize <  corePoolSize && addIfUnderCorePoolSize(command))
                return;
            if (workQueue.offer(command))
                return;
            Runnable r = addIfUnderMaximumPoolSize(command);
            if (r == command)
                return;
            if (r == null) {
                reject(command);
                return;
            }
            // else retry
        }
}

Executes the given task sometime in the future. The task may execute in a new thread or in an existing pooled thread. If the task cannot be submitted for execution, either because this executor has been shutdown or because its capacity has been reached, the task is handled by the current RejectedExecutionHandler.

 protected  void finalize() 
{
        shutdown();
}

Invokes shutdown when this executor is no longer referenced.

 public int getActiveCount() 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            int n = 0;
            for (Worker w : workers) {
                if (w.isActive())
                    ++n;
            }
            return n;
        } finally {
            mainLock.unlock();
        }
}

Returns the approximate number of threads that are actively executing tasks.

 public long getCompletedTaskCount() 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            long n = completedTaskCount;
            for (Worker w : workers)
                n += w.completedTasks;
            return n;
        } finally {
            mainLock.unlock();
        }
}

Returns the approximate total number of tasks that have completed execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation, but one that does not ever decrease across successive calls.

 public int getCorePoolSize() 
{
        return corePoolSize;
}

Returns the core number of threads.

 public long getKeepAliveTime(TimeUnit unit) 
{
        return unit.convert(keepAliveTime, TimeUnit.NANOSECONDS);
}

Returns the thread keep-alive time, which is the amount of time which threads in excess of the core pool size may remain idle before being terminated.

 public int getLargestPoolSize() 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            return largestPoolSize;
        } finally {
            mainLock.unlock();
        }
}

Returns the largest number of threads that have ever simultaneously been in the pool.

 public int getMaximumPoolSize() 
{
        return maximumPoolSize;
}

Returns the maximum allowed number of threads.

 public int getPoolSize() 
{
        return poolSize;
}

Returns the current number of threads in the pool.

 public BlockingQueue<Runnable> getQueue() 
{
        return workQueue;
}

Returns the task queue used by this executor. Access to the task queue is intended primarily for debugging and monitoring. This queue may be in active use. Retrieving the task queue does not prevent queued tasks from executing.

 public RejectedExecutionHandler getRejectedExecutionHandler() 
{
        return handler;
}

Returns the current handler for unexecutable tasks.

 Runnable getTask() throws InterruptedException 
{
        for (;;) {
            switch(runState) {
            case RUNNING: {
                if (poolSize < = corePoolSize)   // untimed wait if core
                    return workQueue.take();
                long timeout = keepAliveTime;
                if (timeout < = 0) // die immediately for 0 timeout
                    return null;
                Runnable r =  workQueue.poll(timeout, TimeUnit.NANOSECONDS);
                if (r != null)
                    return r;
                if (poolSize  > corePoolSize) // timed out
                    return null;
                // else, after timeout, pool shrank so shouldn't die, so retry
                break;
            }
            case SHUTDOWN: {
                // Help drain queue 
                Runnable r = workQueue.poll();
                if (r != null)
                    return r;
                // Check if can terminate
                if (workQueue.isEmpty()) {
                    interruptIdleWorkers();
                    return null;
                }
                // There could still be delayed tasks in queue.
                // Wait for one, re-checking state upon interruption
                try {
                    return workQueue.take();
                } catch(InterruptedException ignore) {}
                break;
            }
            case STOP:
                return null;
            default:
                assert false; 
            }
        }
}

Get the next task for a worker thread to run.

 public long getTaskCount() 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            long n = completedTaskCount;
            for (Worker w : workers) {
                n += w.completedTasks;
                if (w.isActive())
                    ++n;
            }
            return n + workQueue.size();
        } finally {
            mainLock.unlock();
        }
}

Returns the approximate total number of tasks that have been scheduled for execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation, but one that does not ever decrease across successive calls.

 public ThreadFactory getThreadFactory() 
{
        return threadFactory;
}

Returns the thread factory used to create new threads.

 protected  void interruptIdleWorkers() 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            for (Worker w : workers)
                w.interruptIfIdle();
        } finally {
            mainLock.unlock();
        }
}

Wake up all threads that might be waiting for tasks.

 public boolean isShutdown() 
{
        return runState != RUNNING;
}

 public boolean isTerminated() 
{
        return runState == TERMINATED;
}

 public boolean isTerminating() 
{
        return runState == STOP;
}

Returns true if this executor is in the process of terminating after shutdown or shutdownNow but has not completely terminated. This method may be useful for debugging. A return of true reported a sufficient period after shutdown may indicate that submitted tasks have ignored or suppressed interruption, causing this executor not to properly terminate.

 public int prestartAllCoreThreads() 
{
        int n = 0;
        while (addIfUnderCorePoolSize(null))
            ++n;
        return n;
}

Starts all core threads, causing them to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed.

 public boolean prestartCoreThread() 
{
        return addIfUnderCorePoolSize(null);
}

Starts a core thread, causing it to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed. This method will return false if all core threads have already been started.

 public  void purge() 
{
        // Fail if we encounter interference during traversal
        try {
            Iterator< Runnable > it = getQueue().iterator();
            while (it.hasNext()) {
                Runnable r = it.next();
                if (r instanceof Future< ? >) {
                    Future< ? > c = (Future< ? >)r;
                    if (c.isCancelled())
                        it.remove();
                }
            }
        }
        catch(ConcurrentModificationException ex) {
            return; 
        }
}

Tries to remove from the work queue all Future tasks that have been cancelled. This method can be useful as a storage reclamation operation, that has no other impact on functionality. Cancelled tasks are never executed, but may accumulate in work queues until worker threads can actively remove them. Invoking this method instead tries to remove them now. However, this method may fail to remove tasks in the presence of interference by other threads.

 protected  void reject(Runnable command) 
{
        handler.rejectedExecution(command, this);
}

Invoke the rejected execution handler for the given command.

 public boolean remove(Runnable task) 
{
        return getQueue().remove(task);
}

Removes this task from the executor's internal queue if it is present, thus causing it not to be run if it has not already started.

This method may be useful as one part of a cancellation scheme. It may fail to remove tasks that have been converted into other forms before being placed on the internal queue. For example, a task entered using submit might be converted into a form that maintains Future status. However, in such cases, method ThreadPoolExecutor#purge may be used to remove those Futures that have been cancelled.

 public  void setCorePoolSize(int corePoolSize) 
{
        if (corePoolSize <  0)
            throw new IllegalArgumentException();
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            int extra = this.corePoolSize - corePoolSize;
            this.corePoolSize = corePoolSize;
            if (extra <  0) {
                Runnable r;
                while (extra++ <  0 && poolSize <  corePoolSize &&
                       (r = workQueue.poll()) != null)
                    addThread(r).start();
            }
            else if (extra  > 0 && poolSize  > corePoolSize) {
                Iterator< Worker > it = workers.iterator();
                while (it.hasNext() &&
                       extra--  > 0 &&
                       poolSize  > corePoolSize &&
                       workQueue.remainingCapacity() == 0) 
                    it.next().interruptIfIdle();
            }
        } finally {
            mainLock.unlock();
        }
}

Sets the core number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle. If larger, new threads will, if needed, be started to execute any queued tasks.

 public  void setKeepAliveTime(long time,
    TimeUnit unit) 
{
        if (time <  0)
            throw new IllegalArgumentException();
        this.keepAliveTime = unit.toNanos(time);
}

Sets the time limit for which threads may remain idle before being terminated. If there are more than the core number of threads currently in the pool, after waiting this amount of time without processing a task, excess threads will be terminated. This overrides any value set in the constructor.

 public  void setMaximumPoolSize(int maximumPoolSize) 
{
        if (maximumPoolSize < = 0 || maximumPoolSize <  corePoolSize)
            throw new IllegalArgumentException();
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            int extra = this.maximumPoolSize - maximumPoolSize;
            this.maximumPoolSize = maximumPoolSize;
            if (extra  > 0 && poolSize  > maximumPoolSize) {
                Iterator< Worker > it = workers.iterator();
                while (it.hasNext() &&
                       extra  > 0 &&
                       poolSize  > maximumPoolSize) {
                    it.next().interruptIfIdle();
                    --extra;
                }
            }
        } finally {
            mainLock.unlock();
        }
}

Sets the maximum allowed number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle.

 public  void setRejectedExecutionHandler(RejectedExecutionHandler handler) 
{
        if (handler == null)
            throw new NullPointerException();
        this.handler = handler;
}

Sets a new handler for unexecutable tasks.

 public  void setThreadFactory(ThreadFactory threadFactory) 
{
        if (threadFactory == null)
            throw new NullPointerException();
        this.threadFactory = threadFactory;
}

Sets the thread factory used to create new threads.

 public  void shutdown() 
{
        // Fail if caller doesn't have modifyThread permission
	SecurityManager security = System.getSecurityManager();
	if (security != null) 
            java.security.AccessController.checkPermission(shutdownPerm);
        boolean fullyTerminated = false;
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            if (workers.size()  > 0) {
                // Check if caller can modify worker threads.  This
                // might not be true even if passed above check, if
                // the SecurityManager treats some threads specially.
                if (security != null) {
                    for (Worker w: workers)
                        security.checkAccess(w.thread);
                }
                int state = runState;
                if (state == RUNNING) // don't override shutdownNow
                    runState = SHUTDOWN;
                try {
                    for (Worker w: workers)
                        w.interruptIfIdle();
                } catch(SecurityException se) {
                    // If SecurityManager allows above checks, but
                    // then unexpectedly throws exception when
                    // interrupting threads (which it ought not do),
                    // back out as cleanly as we can. Some threads may
                    // have been killed but we remain in non-shutdown
                    // state.
                    runState = state; 
                    throw se;
                }
            }
            else { // If no workers, trigger full termination now
                fullyTerminated = true;
                runState = TERMINATED;
                termination.signalAll();
            }
        } finally {
            mainLock.unlock();
        }
        if (fullyTerminated)
            terminated();
}

Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.

 public List<Runnable> shutdownNow() 
{
        // Almost the same code as shutdown()
	SecurityManager security = System.getSecurityManager();
	if (security != null) 
            java.security.AccessController.checkPermission(shutdownPerm);
        boolean fullyTerminated = false;
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            if (workers.size()  > 0) {
                if (security != null) {
                    for (Worker w: workers)
                        security.checkAccess(w.thread);
                }
                int state = runState;
                if (state != TERMINATED)
                    runState = STOP;
                try {
                    for (Worker w : workers)
                        w.interruptNow();
                } catch(SecurityException se) {
                    runState = state; // back out;
                    throw se;
                }
            }
            else { // If no workers, trigger full termination now
                fullyTerminated = true;
                runState = TERMINATED;
                termination.signalAll();
            }
        } finally {
            mainLock.unlock();
        }
        if (fullyTerminated)
            terminated();
        return Arrays.asList(workQueue.toArray(EMPTY_RUNNABLE_ARRAY));
}

Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.

This implementation cancels tasks via Thread#interrupt , so if any tasks mask or fail to respond to interrupts, they may never terminate.

 protected  void terminated() 
{

}

Method invoked when the Executor has terminated. Default implementation does nothing. Note: To properly nest multiple overridings, subclasses should generally invoke super.terminated within this method.

  void workerDone(Worker w) 
{
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            completedTaskCount += w.completedTasks;
            workers.remove(w);
            if (--poolSize  > 0)
                return;
            // Else, this is the last thread. Deal with potential shutdown.
            int state = runState;
            assert state != TERMINATED;
            if (state != STOP) {
                // If there are queued tasks but no threads, create
                // replacement.
                Runnable r = workQueue.poll();
                if (r != null) {
                    addThread(r).start();
                    return;
                }
                // If there are some (presumably delayed) tasks but
                // none pollable, create an idle replacement to wait.
                if (!workQueue.isEmpty()) { 
                    addThread(null).start();
                    return;
                }
                // Otherwise, we can exit without replacement
                if (state == RUNNING)
                    return;
            }
            // Either state is STOP, or state is SHUTDOWN and there is
            // no work to do. So we can terminate.
            termination.signalAll();
            runState = TERMINATED;
            // fall through to call terminate() outside of lock.
        } finally {
            mainLock.unlock();
        }
        assert runState == TERMINATED;
        terminated();
}

Perform bookkeeping for a terminated worker thread.