Concurrency primitives¶

Category: Foundations · Status: stub

One line: The building blocks a language or library provides for concurrent code, in four groups: synchronization (mutex, semaphore, condition variable), communication (channels, futures), task management (threads, tasks, pools) and atomics.

Also called: synchronization primitives, communication primitives.

How it connects¶

See also: Atomic variable, Channel, Condition variable, Future and promise, Mutex, Semaphore, Thread, Thread pool and executor

In each language¶


Rust	`std::sync` ↗ (`Mutex`, `RwLock`, `Condvar`, `Barrier`, `mpsc`, atomics) and `std::thread` ↗
Go	Channels in the language; `sync` ↗, whose documentation says higher-level synchronization is better done with channels; and `sync/atomic` ↗
C	POSIX `<pthread.h>` ↗, and C11's `<threads.h>` ↗ and `<stdatomic.h>` ↗
C++	The concurrency support library ↗: threads, mutexes, condition variables, semaphores, futures and atomics
Java	`java.util.concurrent` ↗, its `locks` and `atomic` subpackages, and the monitor every object has (`synchronized`, `wait` ↗, `notify`)
Python	`threading` ↗ (`Lock`, `Condition`, `Semaphore`, `Event`, `Barrier`) and `queue` ↗, with counterparts in `asyncio` ↗
C#	Overview of synchronization primitives ↗
JavaScript	Workers exchange messages with `postMessage` ↗; shared memory is a `SharedArrayBuffer` coordinated with `Atomics` ↗
Kotlin	`Mutex` ↗ and `Semaphore` for coroutines, which suspend rather than block; `Channel` ↗
Erlang and Elixir	Processes and messages; ETS ↗ is built-in term storage for very large quantities of data
Haskell	`MVar` ↗ and `Chan` ↗ in `base`; `TVar` in the `stm` ↗ package
The operating system	`futex(2)` ↗: a blocking construct for shared-memory synchronization, with most of the work done in user space

Where to read more¶

Notes: concurrency primitives ↗