A Tour of Common Concurrent Hash Table Designs
4 months ago
- #concurrency
- #hashmap
- #performance
- The article discusses various strategies for building thread-safe hash maps, starting with a global lock approach, which is simple but lacks scalability under concurrent access.
- Lock striping/sharding is introduced as a method to reduce contention by distributing locks across multiple segments of the hash map, improving parallelism.
- Java's ConcurrentHashMap is highlighted for its fine-grained locking strategy, using CAS operations and bin-local locks to minimize contention and allow concurrent operations on different bins.
- Cliff Click's NonBlockingHashMap (NBHM) is presented as a lock-free alternative, utilizing CAS-based updates and cooperative resizing to achieve high scalability under heavy update loads.
- The article emphasizes the trade-offs between simplicity, scalability, and implementation complexity across different concurrency strategies in hash map designs.