running two threads simultaneously inside a stateless agent and guaranting communication between them

Question

I am developing a stateless Agent in Java that takes informations from one Server and transfer it to another client. It means that the agent is located between a client and a server. So I am thinking to run two threads simultaneously on the agent: one thread (thread1) runs a serverSocket and get request from client while another threads (thread2)is runnning and makes communication with the server. The problem consists in synchronizing between the two threads. I am thinking in making thread 1 asking whole the time thread 2 about a new Information. If thread 2 has nothing new, he will not answer it. What is the best way to synchronize between them. Should I use a global variable (a flag) to synchronize between them? Can I save Information when I have a stateless agent?

Answer 1

I think you should modify your app into async model.

Your app needs:
- an entry point to accept incoming connections -> a good example is an async servlet (or one dedicated thread).
- a ThreadPoolExecutor that provides fixed numbers of workers and a blocking queue (use this constructor).

The workflow:

1. Accept incomming request.
2. Wrapp incoming request into (Runnable) task.
3. Put task into blocking queue.
4. If ThreadPoolExecutor has a free worker starts processing the task

An advantage of such a model is that you are able to handle one request using one thread. So there is no need to manually synchronize anything.