Atom
An atom is a Clojure reference type that supports synchronous, independent, coordinated updates to shared state without explicit locks.
Data-Oriented Programming: Reduce software complexity
An atom is a concurrency-control mechanism that provides coordinated updates to shared state without requiring explicit locks.
- How it is used
- Manages shared counters, caches, and complete system state in multithreaded environments without explicit locks.
- How deep it goes
- Explains get, set, swap, immutable reads, and compare-and-set retries, while deferring detailed starvation analysis.
- Examples
- Uses a database-access counter, an immutable string-map cache, and reconciled system state as progressive examples.
- What you can do after
- Apply it via get, set, and swap to build thread-safe state updates without lock-related deadlocks.
Read how Data-Oriented Programming: Reduce software complexity explains atom →
Clojure: The Essential Reference
clojure.lang.Atom is the Clojure runtime class that wraps a Java AtomicReference to implement atom state management.
- How it is used
- Coordinates synchronous, uncoordinated access to a single shared state reference without explicit locking.
- How deep it goes
- Defines retrying updates, reset semantics, CAS behavior, dereferencing, and the AtomicReference wrapper through executable examples.
- Examples
- Uses counters, nested maps, configuration state, bounded CAS retries, and memoization caches.
- What you can do after
- Apply atom, swap!, reset!, compare-and-set!, and dereferencing to manage shared state.
Related concepts
- concurrency primitivekind of · A concurrency primitive is a fundamental mechanism, construct, or protocol for coordinating concurrent execution and controlling access to shared state or resources.
- memoizationused by · Memoization is an optimization technique that stores computation results with their inputs so equivalent later evaluations can reuse them without recomputation.
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