Computer Science

Concurrency, explained

Concurrency is the ability of a system to make progress on multiple tasks during overlapping time periods.
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Part of the Semantic Notion technical glossary.

Short Definition

Concurrency is the ability of a system to make progress on multiple tasks during overlapping time periods.

Intuition

Concurrent work may interleave, run in parallel, or both. The hard part is coordinating shared state safely.

Technical Definition

Concurrency concerns the structure and correctness of computations composed of multiple independently progressing tasks, threads, processes, or events.

Example

A web server handles many client requests concurrently.

Common Misunderstandings

Concurrency is not the same as parallelism.
Concurrent programs can fail even when each individual operation looks correct.

Same Category

More from Computer Science

AlgorithmAn algorithm is a precise procedure for solving a problem or computing a result.Byzantine Fault ToleranceByzantine fault tolerance is the ability of a distributed system to keep working even when some nodes behave arbitrarily or maliciously.CacheA cache stores recently or frequently used data in a faster location so future access is quicker.Cache CoherenceCache coherence is the property that multiple caches maintain a consistent view of shared data.CAP TheoremCAP theorem says a distributed data system cannot simultaneously guarantee consistency, availability, and partition tolerance during a network partition.ConsensusConsensus is the process by which distributed nodes agree on a value or sequence of decisions despite failures.

Related Reading

Essays that use this concept

System ProgrammingLinux Kernel Concurrency Mechanisms: Keeping the OS Thread-SafeComputer ScienceThe Dining Philosophers Problem: A Classic Concurrency Challenge

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