Synchronization in computer science denotes techniques that coordinate multiple activities so they behave correctly when executed concurrently or when data copies must agree. The term commonly refers to two related concerns: process synchronization, which orders or coordinates execution among threads or processes, and data synchronization, which keeps multiple replicas of information consistent. For a general introduction see overview resources.

Process synchronization

Process synchronization addresses problems that arise when several computations access shared resources or must reach a rendezvous point. Common goals include enforcing mutual exclusion, preventing race conditions, and coordinating phases of work. Primitive mechanisms and abstractions include:

  • Locks and mutexes: ensure exclusive access to a resource.
  • Semaphores and condition variables: support signaling and waiting between threads.
  • Barriers and rendezvous: make a group of threads wait until all have reached a point.
  • Monitors and transactional memory: higher-level constructs that encapsulate synchronization logic.

These topics are often presented in texts about operating systems and concurrency; for formal descriptions of process coordination see process synchronization material. Protocols that require agreement among participants, such as leader election or commit protocols, are sometimes described under the umbrella of handshake or consensus problems.

Data synchronization

Data synchronization focuses on keeping multiple copies of data in coherence. This can mean strict, transactional consistency where updates are applied atomically across replicas, or weaker models such as eventual consistency used by distributed systems to trade immediacy for availability and partition tolerance. Techniques include:

  • Two‑phase commit and distributed transactions for atomic updates.
  • Version vectors, timestamps, and conflict resolution strategies.
  • Conflict-free replicated data types (CRDTs) and operational transformation for collaborative editing.

Practical details and best practices for synchronizing data across devices, databases, or services are discussed in many engineering guides; see data-synchronization references for further reading.

History, importance, and distinctions

Synchronization concepts evolved as hardware began to support multitasking and distributed systems expanded. Early research established core problems—mutual exclusion, deadlock, and consensus—that still guide design and verification of concurrent and distributed software. Synchronization is distinct from but related to scheduling: scheduling decides when tasks run, while synchronization constrains the relative ordering or visibility of actions. Correct synchronization is essential for reliability, security, and performance in operating systems, databases, networking, and concurrent libraries.

Understanding synchronization helps developers choose appropriate trade-offs between safety and performance, and to reason about liveness (progress) and safety (absence of incorrect outcomes). For conceptual overviews and tutorials, consult an introductory concurrency text or follow the linked resources above.