I am running a for loop and at each iteration, I execute a SwingWorker in background (who lasts around 5 minutes). I have an attribute who is the number of Worker running in background at the same time.
The for loop has 100 iterations but I want only 5 simulutaneous SwingWorker running. How can I pause the loop iteration if the number of simulutaneous worker running if superior to 5 ? how can I resume it when it becomes lower ?
Thank you.
Normally I use an ExecutionService with 5 threads to do this. But you can use a Semaphore like this.
final Semaphore permits = new Semaphore(5);
for(int i=0;i<100;i++) {
permits.acquire();
// add a task
}
// in the SwingWorker
public String doInBackground() {
try {
return findTheMeaningOfLife();
} finally {
permits.release();
}
}
Check out the following blog about SwingWorker throttling and monitoring. It explains how to define a number M of simultaneous threads to execute N tasks.
Basically you'll have to create a threadpool and let that manage the execution of your workers.
http://blogs.oracle.com/swinger/entry/swingworker_throttling_and_monitoring
Assuming the for loop doesn't do anything other than execute your SwingWorkers, one way to do this is by just submitting 100 tasks to a ThreadPoolExecutor with the pool size set to 5.
