sünkroniseerimiskonstruktsioone

Synchronization constructs are mechanisms provided by programming languages and operating systems to coordinate concurrent execution of threads or processes. They ensure that shared resources are accessed in a controlled manner, preventing data races, deadlocks, and other concurrency hazards. Common synchronization constructs include mutexes, semaphores, monitors, condition variables, atomic variables, and barriers, each serving distinct purposes and offering different performance characteristics.

A mutex (mutual exclusion) allows only one thread to own the lock at a time, protecting critical sections. Semaphores generalize this concept by permitting a bounded number of concurrent owners, useful for producer‑consumer patterns. Monitors combine a mutex with condition variables, enabling threads to wait for certain conditions while holding a lock. Condition variables allow threads to sleep until signalled, improving efficiency over busy waiting. Atomic variables provide lock‑free operations on individual data elements, ensuring read–modify–write sequences are indivisible, which is essential for lock‑free data structures.

Bars er such as cyclic barriers enable multiple threads to rendezvous at a single point before continuing. Lock‑free and wait‑free algorithms use atomic primitives to avoid locks entirely, trading off complexity for higher scalability on multi‑core systems. Choosing the appropriate construct depends on the system’s requirements: fine‑grained locking offers higher concurrency but can lead to deadlocks; coarse‑grained locking simplifies reasoning but may reduce performance. Modern languages embed these constructs in libraries, simplifying their use while still demanding careful design to avoid subtle concurrency bugs.