I just found this gem in the javax.swing.SwingWorker (1.7b01) which just doesn't look like the right thing(TM). That would be an application for just using MAX_WORKER_THREADS core threads, the same number of max, plus allowCoreThreadsTimeout, right?
If you agree, I'd submit the change to Sun.
Thanks
Matthias
obj = new ThreadPoolExecutor(0, MAX_WORKER_THREADS,
1L, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(),
threadFactory) {
private final ReentrantLock pauseLock = new ReentrantLock();
private final Condition unpaused = pauseLock.newCondition();
private boolean isPaused = false;
private final ReentrantLock executeLock = new ReentrantLock();
@Override
public void execute(Runnable command) {
/*
* ThreadPoolExecutor first tries to run task
* in a corePool. If all threads are busy it
* tries to add task to the waiting queue. If it
* fails it run task in maximumPool.
*
* We want corePool to be 0 and
* maximumPool to be MAX_WORKER_THREADS
* We need to change the order of the execution.
* First try corePool then try maximumPool
* pool and only then store to the waiting
* queue. We can not do that because we would
* need access to the private methods.
*
* Instead we enlarge corePool to
* MAX_WORKER_THREADS before the execution and
* shrink it back to 0 after.
* It does pretty much what we need.
*
* While we changing the corePoolSize we need
* to stop running worker threads from accepting new
* tasks.
*/
//we need atomicity for the execute method.
executeLock.lock();
try {
pauseLock.lock();
try {
isPaused = true;
} finally {
pauseLock.unlock();
}
setCorePoolSize(MAX_WORKER_THREADS);
super.execute(command);
setCorePoolSize(0);
pauseLock.lock();
try {
isPaused = false;
unpaused.signalAll();
} finally {
pauseLock.unlock();
}
} finally {
executeLock.unlock();
}
}
@Override
protected void afterExecute(Runnable r, Throwable t) {
super.afterExecute(r, t);
pauseLock.lock();
try {
while(isPaused) {
unpaused.await();
}
} catch(InterruptedException ignore) {
} finally {
pauseLock.unlock();
}
}
};
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