- The memcached is distributed , meaning it is not local. It is based on a network connection (and of course it can also use localhost) to complete the service itself, which is an application-independent program or daemon (daemon mode).
- Memcached uses the libevent library for network connectivity services. Libevent is a library that encapsulates event-handling functions such as Linux's Epoll, BSD-class operating system kqueue, and so on as a unified interface. The Performance of O (1) can be played even if the number of connections to the server increases.
- Memcached is a "distributed" memory object caching system that does not need to be "distributed", does not need to be shared, or is simply small enough to have only one server application, memcached does not bring any benefits, but also slows down system efficiency, because network connectivity also requires resources. The real bottleneck is network connectivity .
- Memcached uses memory to manage data, so it is volatile, when the server restarts, or the memcached process aborts, the data is lost, so memcached cannot be used to persist the data. And when the content capacity reaches the specified value, the unused cache is automatically deleted based on the LRU(Least recently used) algorithm.
- Memcached Although it is a "distributed" cache server, there is no distributed functionality on the server side. Each memcached does not communicate with each other to share information. Depends entirely on the implementation of the client to be distributed.
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http://kb.cnblogs.com/page/42732/
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Distributed Cache Memcache
