Lock Coupling

Understanding hand-over-hand locking in concurrent data structures

This is an easy conceptual question about a foundational synchronization technique in systems programming. It tests whether you understand how to safely traverse shared data structures when multiple threads or processes access them concurrently.

Hand-over-hand locking (also known as lock coupling) is a pattern for managing access to linked or sequential data structures in a multi-threaded environment. The core idea is to maintain invariants about which locks are held and when they can be released as you move through the structure. Questions like this appear in operating-systems interviews and systems design discussions because the technique underpins many practical concurrent algorithms.

• Lock ordering and deadlock prevention
• Granular vs. coarse-grained locking strategies
• Trade-offs between throughput and complexity