crossbeam-epoch

Epoch-based memory reclamation for lock-free data structures in Rust. Provides the Rust ecosystem's equivalent of Read-Copy-Update — allowing readers to access shared data without locks while writers safely defer deallocation of old versions.

crossbeam-epoch underpins most of the Rust concurrent data structure ecosystem, with crossbeam-deque alone having 299M+ downloads. papaya, scc, and other lock-free Rust structures build on epoch-based or similar reclamation schemes.

EBR's place in the reclamation landscape

EBR is one of three production-grade reclamation strategies for lock-free structures, and the right choice depends on which trade-off hurts least:

EBR is the right default for general-purpose Rust concurrent data structures because the common-path cost is the lowest of any safe scheme. It is the wrong choice when threads can stall arbitrarily (kernel-adjacent code, hard-real-time systems) — there hazard pointers' bounded retention or Crystalline's wait-freedom matters more than EBR's amortized speed.

For lock-free linked lists specifically — see fastest-linked-lists — reclamation cost is the dominant overhead, often beating the algorithmic cost of the structure itself. The bw-tree's loss to ART-OLC is a closely related result: the cost of reclamation traffic on shared cache lines drowns the algorithmic win.