Tag: memcache

About

memcached (pronunciation: mem-cache-dee.) is a general-purpose distributed memory caching system that was originally developed by Danga Interactive for LiveJournal, but is now used by many other sites. It is often used to speed up dynamic database-driven websites by caching data and objects in memory to reduce the number of times the database must be read. Memcached is distributed under a permissive free software license.[1]

Memcached lacks authentication and security features, meaning it should only be used on servers with a firewall set up appropriately. By default, memcached uses the port 11211. Among other technologies, it uses libevent.

Memcached's APIs provides a giant 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. Applications using memcached typically layer memcached requests and additions into core before falling back on a slower backing store, such as a database.

From en.wikipedia.org/wiki/Memcache

 

In PHP, sessions can keep track of authenticated in users. They are an essential building block in today's websites with big communities and a lot of user activity. Without sessions, everyone would be an anonymous visitor. In system terms, PHP sessions are little files, stored on the server's disk. But on high traffic sites, the disk I/O involved, and not being able to share sessions between multiple webservers make this default system far from ideal. This is how to enhance PHP session management in terms of performance and shareability.