SyncMutexes

SyncMutexes are a class of synchronization primitives that provide mutual exclusion to protect shared data in concurrent software. A mutex allows a thread to enter a critical section by acquiring the lock and to exit by releasing it, ensuring only one thread executes the protected code at a time. Mutexes are fundamental to data race prevention in multi-threaded programs.

Most implementations offer blocking lock attempts, where a thread waits until the lock becomes available, and non-blocking try-locks, which return immediately if the lock is held. Some mutexes also support timed attempts or recursive (reentrant) locking, where the same thread can acquire the lock multiple times.

Common variants include plain mutexes, recursive mutexes, and read-write mutexes. Blocking mutexes are typically backed by OS-level primitives; spinlocks offer busy-waiting for short critical sections but can waste CPU cycles under contention. Priority-inheritance or related mechanisms may be used to address priority inversion in priority-based schedulers, depending on the platform.

Usage patterns emphasize small, well-defined critical sections. Many languages provide RAII-style wrappers or defer/finally semantics to ensure locks are released even on errors. Avoid performing long-running operations while holding a mutex, and be careful to acquire locks in a consistent order to prevent deadlocks.

Deadlocks, livelocks, and data races are key risks. Good practice includes minimizing lock duration, using finer-grained or higher-level concurrency constructs when possible, and testing under concurrency. When performance is critical, alternatives such as lock-free data structures, atomic variables, or channel-based communication can reduce the need for mutex contention.