Crate crossbeam

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Crossbeam supports concurrent programming, especially focusing on memory management, synchronization, and non-blocking data structures.

Crossbeam consists of several submodules:

  • atomic for enhancing std::sync API. AtomicConsume provides C/C++11-style “consume” atomic operations (re-exported from [crossbeam-utils]). ArcCell provides atomic storage and retrieval of Arc.

  • utils and thread for utilities, re-exported from [crossbeam-utils]. The “scoped” thread API in thread makes it possible to spawn threads that share stack data with their parents. The utils::CachePadded struct inserts padding to align data with the size of a cacheline. This crate also seeks to expand the standard library’s few synchronization primitives (locks, barriers, etc) to include advanced/niche primitives, as well as userspace alternatives.

  • epoch for memory management, re-exported from [crossbeam-epoch]. Because non-blocking data structures avoid global synchronization, it is not easy to tell when internal data can be safely freed. The crate provides generic, easy to use, and high-performance APIs for managing memory in these cases. We plan to support other memory management schemes, e.g. hazard pointers (HP) and quiescent state-based reclamation (QSBR).

  • Concurrent data structures which are non-blocking and much superior to wrapping sequential ones with a Mutex. Crossbeam currently provides channels (re-exported from [crossbeam-channel]), deques (re-exported from [crossbeam-deque]), queues, and stacks. Ultimately the goal is to also include bags, sets and maps.


Additional utilities for atomics.
Multi-producer multi-consumer channels for message passing.
A concurrent work-stealing deque.
Epoch-based memory reclamation.
Concurrent queues.
Concurrent stacks.
Utilities for thread synchronization.
Threads that can borrow variables from the stack.
Utilities for concurrent programming.


Creates a new scope for spawning threads.