How to run concurrency unit test?

Question

How to use junit to run concurrency test?

Let's say I have a class

public class MessageBoard {     public synchronized void postMessage(String message)     {         ....     }      public void updateMessage(Long id, String message)     {         ....     } } 

I wan to test multiple access to this postMessage concurrently. Any advice on this? I wish to run this kind of concurrency test against all my setter functions (or any method that involves create/update/delete operation).

Answer 1

Unfortunately I don't believe you can definitively prove that your code is thread-safe by using run-time testing. You can throw as many threads as you like against it, and it may/may not pass depending on the scheduling.

Perhaps you should look at some static analysis tools, such as PMD, that can determine how you're using synchronisation and identify usage problems.

Answer 2

I would recommend using MultithreadedTC - Written by the concurrency master himself Bill Pugh (and Nat Ayewah). Quote from their overview:

MultithreadedTC is a framework for testing concurrent applications. It features a metronome that is used to provide fine control over the sequence of activities in multiple threads.

This framework allows you to deterministically test every thread interleaving in separate tests