Reducing Context Switch Overhead

Summary

Because one of the most common reasons to use threads is to exploit multiple processors, in discussing the performance of concurrent applications, we are usually more concerned with throughput or scalability than we are with raw service time. Amdahl's law tells us that the scalability of an application is driven by the proportion of code that must be executed serially. Since the primary source of serialization in Java programs is the exclusive resource lock, scalability can often be improved by spending less time holding locks, either by reducing lock granularity, reducing the duration for which locks are held, or replacing exclusive locks with nonexclusive or nonblocking alternatives.