Memcache概述：
Memcache是一个高性能的分布式的内存对象缓存系统，通过在内存里维护一个统一的巨大的hash表，它能够用来存储各种格式的数据，包括图像、视频、文件以及数据库检索的结果等。简单的说就是将数据调用到内存中，然后从内存中读取，从而大大提高读取速度。
Memcached是以守护程序方式运行于一个或多个服务器中，随时会接收客户端的连接和操作。
Memcache安装：
1:下载libevent与memcache软件包。
libevent下载地址：http://monkey.org/~provos/libevent/
memcache下载地址:http://memcached.org/
2:解压，编译libevent。
# tar -zxvf libevent-2.1.3-alpha.tar.gz
# cd libevent-2.1.3-alpha
# ./configure -prefix=/usr/local/memcache/libevent
# make && make install
3:解压，编译memcache。
# cd ../
# tar -zxvf memcached-1.4.15.tar.gz
# cd memcached-1.4.15
# ./configure --prefix=/usr/local/memcache/ --with-libevent=/usr/local/memcache/libevent
# make && make install
开启memcache，并连接测试：
以守护进程模式启动memcache
# /usr/local/memcache/bin/memcached -d -l 192.168.189.129 -p 11211 -m 2048 -u root
查看memcache是否开启：
客户端连接测试（使用telnet）
#telnet192.168.189.129 11211
能连接上，说明memcache成功启用，可使用stats命令查看当前状态
#stats
STAT pid 29563
STAT uptime 228
STAT time 1377137834
STAT version 1.4.15
STAT libevent 2.1.3-alpha
STAT pointer_size 64
STAT rusage_user 0.000999
STAT rusage_system 0.000999
STAT curr_connections 5
STAT total_connections 6
STAT connection_structures 6
STAT reserved_fds 20
STAT cmd_get 0
STAT cmd_set 0
STAT cmd_flush 0
STAT cmd_touch 0
STAT get_hits 0
STAT get_misses 0
STAT delete_misses 0
STAT delete_hits 0
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 7
STAT bytes_written 0
STAT limit_maxbytes 2147483648
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 0
STAT hash_power_level 16
STAT hash_bytes 524288
STAT hash_is_expanding 0
STAT bytes 0
STAT curr_items 0
STAT total_items 0
STAT expired_unfetched 0
STAT evicted_unfetched 0
STAT evictions 0
STAT reclaimed 0
END