Memcached is a general-purpose distributed memory caching system.

Memcached is often used to speed up dynamic database-driven websites by caching data and objects in RAM to reduce the number of times an external data source (such as a database or API) must be read.

Memcached is free and Open Source software, licensed under the Revised BSD license.

Memcached runs on UNIX-like operating systems (at least Linux and OS X) and on Microsoft Windows and depends on the libevent library.

Memcached's APIs provide a very large Hash table distributed across multiple machines. When the table is full, subsequent inserts cause older data to be purged in Least Recently Used (LRU) order.

Memcached has no internal mechanism to track misses which may happen. There are some 3rd party applications such as mctop which can be used or if your operating system support Dtrace you can use dtrace script.

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