Hazard pointers¶

Category: Lock-free · Status: stub

One line: Each thread publishes the pointers it is about to use, and memory is freed only when no thread has it published — safe memory reclamation for lock-free data structures.

Also called: safe memory reclamation.

How it connects¶

flowchart LR
  n_aba_problem["ABA problem"]
  n_hazard_pointers["Hazard pointers"]
  n_hazard_pointers -->|prevents| n_aba_problem
  classDef center stroke-width:3px
  class n_hazard_pointers center
  classDef outside stroke-dasharray: 4 3
  class n_aba_problem outside

Helps prevent: ABA problem
See also: Concurrent data structures, Lock-free, Read-copy-update

In each language¶


C++	`<hazard_pointer>` ↗ (C++26): `hazard_pointer_obj_base`, `hazard_pointer` and `make_hazard_pointer`

Where to read more¶

In the books: Hands-On Concurrency with Rust, Brian L. Troutwine — ch. 7, 'Atomics – Safely Reclaiming Memory'
In the books: The Art of Multiprocessor Programming, Maurice Herlihy, Nir Shavit — ch. 10, 'Concurrent Queues and the ABA Problem' → 'Memory Reclamation and the ABA Problem'
Reference: Wikipedia: Hazard pointer ↗