memcache lease

RU: memcache lease

A mechanism introduced in Facebook's Memcached deployment (NSDI 2013) to prevent two cache pathologies simultaneously. On a miss, the server issues a unique lease token to exactly one client per key; only that token holder may write the new value back. Simultaneously, other readers are told to wait and retry, preventing a stampede. If a delete arrives before the write, the token is invalidated to prevent stale sets.