11.4. Reducing Lock Contention

We’ve seen that serialization hurts scalability and that context switches hurt performance. Contended locking causes both, so reducing lock contention can improve both performance and scalability.

Access to resources guarded by an exclusive lock is serialized—only one thread at a time may access it. Of course, we use locks for good reasons, such as preventing data corruption, but this safety comes at a price. Persistent contention for a lock limits scalability.