Performance Guidelines

We cannot stress enough the importance of having a concurrent program running correctly before trying to improve the performance. Also, before applying any of these guidelines related to performance, we first need to set up a reliable way of measuring what we are trying to improve.

Avoid contention

Whenever multiple threads are using shared data, there will be contention. Contention hurts performance, and sometimes the overhead caused by contention can make a parallel algorithm work slower than a single-threaded alternative.