Question

I am working on a java server which dispatches xmpp messages and workers execute the tasks from my clients.

private static ExecutorService threadpool = Executors.newCachedThreadPool();

DispatchWorker worker = new DispatchWorker(connection, packet);
threadpool.execute(worker);

Works fine, but i need a bit more than that.

1. I don’t want to execute the same request multiple times.
2. My worker may start another thread with a backround task also only allowed to run once at a time. A Threadpool in the worker threads.

I can identify the requests by a string and i can also give the backround tasks an id to identify them.

My solution would be a synchronized hashmap where my running tasks are registered with their id. The reference of the map will be passed to the worker threads that they remove their entry when they finished.

Feels a bit clumsy this solution so i wanted to know if there are more elegant patterns/best practices.

best regards, m

Answer 1

This is exactly what Quartz does (although it does a lot more, like scheduling jobs in the future).