centos6.5用memcached 来作PHP 的session.save_handler
php有两个memcache模块，一个是php-memcache,一个是php-memcached,php-memcached是最新的，也是比较稳定的，网上的太多的资料都是关于php-memcache的，太少提到php-memcached,而php-memcached的配置跟php-memcache是有所不同的。我的环境是多台webServer，全安装了nginx+php,3台memcached 服务器。webserver_IP:192.168.10.9----22memcachedserver_IP:192.168.10.23--25
一、先安装好web服务器，LNMP一键安装，此处就不多加强调了。二、安装memcached服务器。三、在所有的webServer上安装php扩展，
安装包： memcached 服务器端所需： libevent-2.0.21-stable.tar.gz memcached-1.4.24.tar.gz 支持PHP扩展所需： libmemcached-1.0.18.tar.gz memcached-2.2.0.tgz
在memcached服务器端：1、安装libevent-2.0.21-stablewget http://nchc.dl.sourceforge.net/project/levent/libevent/libevent-2.0/libevent-2.0.22-stable.tar.gztar xzvf libevent-1.4.9-stable.tar.gz
cd libevent-1.4.10-stable./configure --prefix=/usr
make && make install
2、安装memcached-1.4.24wget http://www.memcached.org/files//memcached-1.4.24.tar.gzcd /software
tar xzvf memcached-1.4.24.tar.gz
cd memcached-1.4.24
./configure --prefix=/usr/local/memcached --with-libevent=/usr/local/
make && make install
3、启动memcached/usr/local/memcached/bin/memcached -d -m 10000 -p 11211 -u root -c 4096 -P /usr/local/memcached/logs/memcached.pid
执行后，远程登录任意一台memcached服务器，可以用以下办法查看执行状态telnet 192.168.10.23 11211statsSTAT pid 11568
STAT uptime 5910
STAT time 1241876672
STAT version 1.2.8
STAT pointer_size 32
STAT rusage_user 0.751885
STAT rusage_system 1.584759
STAT curr_items 2615
STAT total_items 36753
STAT bytes 244835
STAT curr_connections 3
STAT total_connections 18427
STAT connection_structures 36
STAT cmd_flush 0
STAT cmd_get 18388
STAT cmd_set 38334
STAT get_hits 15717
STAT get_misses 2671
STAT evictions 0
STAT bytes_read 4924864
STAT bytes_written 1992526
STAT limit_maxbytes 134217728
STAT threads 2
STAT accepting_conns 1
STAT listen_disabled_num 0
END
有以上信息出现，表明启动成功！
4、加入开机启动vim /etc/rc.local #最后一行加入：/usr/local/memcached/bin/memcached -d -m 10000 -p 11211 -u root -c 4096 -P /usr/local/memcached/logs/memcached.pid在webserver上安装，实现扩展1、安装zlibyum install zlib
2、安装libmemcachedwget https://launchpadlibrarian.net/165454254/libmemcached-1.0.18.tar.gztar zxvf libmemcached-0.26.tar.gzcd libmemcached-0.26
./configure --prefix=/usr/local/libmemcached/make && make install
3、安装php-memcached模块wget http://pecl.php.net/get/memcached-2.2.0.tgz
2.2.0stable2014-04-01memcached-2.2.0.tgz (68.8kB)
tar -zxvf memcached-2.2.0.tgzcdmemcached-2.2.0phpize
./configure --with-php-config=/usr/bin/php-config --enable-memcache --with-libmemcached-dir=/usr/local/libmemcachedmake make installmake install 结束后：# make install
Installing shared extensions: /Data/app/php/lib/php/extensions/no-debug-non-zts-20131226/
4、编辑php.inivim /etc/php.ini修改extension_dir的路径为你的默认的是：extension_dir= "./"可以修改为：extension_dir= "./"在文件最后加入:extension = "/Data/app/php/lib/php/extensions/no-debug-non-zts-20131226/"
也可以不修改extension的路径，直接在最后添加：extension = "/Data/app/php/lib/php/extensions/no-debug-non-zts-20131226/memcached.so"
修改php.inisession.save_handler = files-> session.save_handler = memcached
session.save_path = "/var/lib/php/session" -> session.save_path = "192.168.10.23:11211;/opt/"
9、重启apacheservice httpd restart
测试：vim test.php<?php
$memcache_obj = new Memcached();
$memcache_obj->addServer('192.168.1.23', 11211);
$memcache_obj->set('key','memcache 测试!',false, 10) or die ("Failed to save data at the server");
echo $memcache_obj->get('key');
?>
:wq# /usr/local/php/bin/php test.php# /Data/app/php5.6.11/bin/php testmem2.php
memcache 测试!
#
# vim testmem2.php 将192.168.1.23改成一错的，192.168.1.231，保存再测试。
# /Data/app/php5.6.11/bin/php testmem2.php
Failed to save data at the server
#
1、安装libmemcached需要先安装zlib2、php.ini文件的配置，php-memcached模块跟php-memcache不同，要设成是memcached,这个在phpinfo页面的Registered save handlers可以看到。如果设置不正确，会有"Cannot find save handler memcache"的错误提示。3、session.save_path几乎所有的资料都是session.save_path = "tcp://127.0.0.1:11211"，但这可能在memcaceh是这样用的，我没有验证，我一开始也是这样设置，但一直出现"Failed to write session data (memcached)"的错误，找了很入也没找到是什么原因，后来在php.net上找到
[*]session.save_path string
[*]Defines a comma separated of hostname:port entries to use for session server pool, for example"sess1:11211, sess2:11211".
[*]
这段说明，于是去掉tcp://再试，才终于成功！
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