MemC3: Compact and Concurrent MemCache with Dumber Caching and Smarter Hashing

This paper presents a set of architecturally and workload inspired algorithmic and engineering improvements to the popular Memcached system that substantially improve both its memory efficiency and throughput. These techniques—optimistic cuckoo hashing, a compact LRU-approximating eviction algorithm based uponCLOCK, and comprehensive implementation of optimistic locking—enable the resulting system to use 30% less memory for small key-value pairs, and serve up to 3x as many queries per second over the network. We have implemented these modifications in a system we call MemC3—Memcached with CLOCK and Concurrent Cuckoo hashing—but believe that they also apply more generally to many of today’s read-intensive, highly concurrent networked storage and caching systems.