(转)Memcached笔记——（一）安装&常规错误&监控

Memcached笔记——（一）安装&常规错误&监控

link:http://snowolf.iteye.com/blog/1447348

08年的时候接触过Memcached，当时还对它的客户端产品嗤之以鼻，毕竟手工代码没有各种ORM原生XML配置方便。尽管如此，Memcached现在已经成了服务器架构里不可或缺的一部分！

一、下载
1.Libevent
简单的说就是一个事件触发的网络库，Memcached离不开它。

wget http://cloud.github.com/downloads/libevent/libevent/libevent-2.0.17-stable.tar.gz

wget http://cloud.github.com/downloads/libevent/libevent/libevent-2.0.17-stable.tar.gz

2.Memcached
今天的主角

wget http://memcached.googlecode.com/files/memcached-1.4.13.tar.gz

wget http://memcached.googlecode.com/files/memcached-1.4.13.tar.gz

二、安装
1.Libevent
解压缩

tar zxvf libevent-2.0.17-stable.tar.gz

tar zxvf libevent-2.0.17-stable.tar.gz

编译、安装

./configure --prefix=/usr && make && make install

./configure --prefix=/usr && make && make install 

这里一定要注意指定--prefix，后面配置memcached的时候就有必要用到。
2.Memcached
解压

tar zxvf memcached-1.4.13.tar.gz

tar zxvf memcached-1.4.13.tar.gz

编译、安装

./configure --with-libevent=/usr/lib && make && make install

./configure --with-libevent=/usr/lib && make && make install

这里一定要指定libevent的路径，否则启动的时候就有找不到libevent的so文件的错误！
启动

memcached -d -m 50 -p 11211 -u root -P /tmp/memcached.pid

memcached -d -m 50 -p 11211 -u root -P /tmp/memcached.pid

参数

引用

-p <num> TCP port number to listen on (default: 11211)
-U <num> UDP port number to listen on (default: 11211, 0 is off)
-l <addr> interface to listen on (default: INADDR_ANY, all addresses)
<addr> may be specified as host:port. If you don't specify
a port number, the value you specified with -p or -U is
used. You may specify multiple addresses separated by comma
or by using -l multiple times
-d run as a daemon
-u <username> assume identity of <username> (only when run as root)
-m <num> max memory to use for items in megabytes (default: 64 MB)
-M return error on memory exhausted (rather than removing items)
-c <num> max simultaneous connections (default: 1024)
-v verbose (print errors/warnings while in event loop)
-P <file> save PID in <file>, only used with -d option

是否正常？Telnet上去看看

telnet xxx.xxx.xxx.xxx 11211

telnet xxx.xxx.xxx.xxx 11211

然后输入

stats

stats

接着就能看到：

引用

STAT pid 3021
STAT uptime 3621
STAT time 1331261509
STAT version 1.4.13
STAT libevent 2.0.17-stable
STAT pointer_size 64
STAT rusage_user 0.000000
STAT rusage_system 0.000999
STAT curr_connections 6
STAT total_connections 7
STAT connection_structures 7
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 72
STAT bytes_written 1038
STAT limit_maxbytes 52428800
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 expired_unfetched 0
STAT evicted_unfetched 0
STAT bytes 0
STAT curr_items 0
STAT total_items 0
STAT evictions 0
STAT reclaimed 0
END

上面状况说明Memcached服务正常。
还可以试试get、set、delete、replace

引用

set foo 0 0 3 （保存命令）
bar （数据）
STORED （结果）
get foo （取得命令）
VALUE foo 0 3 （数据）
bar （数据）

输入

quit

quit

退出。
三、常规错误
一开始没有指定libevent路径安装memcached的时候，启动memcached就报这个错误：

引用

memcached: error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory

其实这个文件就在/usr/lib下。错就错在Linux是64bit系统，如果没有指定libevent路径，memcached就会去/usr/lib64下去找。
找到这个文件

whereis libevent-2.0.so.5

whereis libevent-2.0.so.5

引用

libevent-2.0.so: /usr/local/lib/libevent-2.0.so.5

ldd /usr/bin/memcached

ldd /usr/bin/memcached

提示找不到libevent-2.0.so.5

引用

libevent-2.0.so.5 => not found

libpthread.so.0 => /lib64/libpthread.so.0 (0x00000032f2600000)

libc.so.6 => /lib64/libc.so.6 (0x00000032f1a00000)

/lib64/ld-linux-x86-64.so.2 (0x00000032f1600000)

定位

LD_DEBUG=libs /usr/bin/memcached -v

LD_DEBUG=libs /usr/bin/memcached -v

注意这句：

引用

9873: trying file=/usr/lib64/libevent-2.0.so.5

做个软连接

ln -s /usr/local/lib/libevent-2.0.so.5 /usr/lib64/libevent-2.0.so.5

ln -s /usr/local/lib/libevent-2.0.so.5 /usr/lib64/libevent-2.0.so.5

再试试：

ldd /usr/local/bin/memcached

ldd /usr/local/bin/memcached

这回找到了！

引用

libevent-2.0.so.5 => /usr/lib64/libevent-2.0.so.5 (0x00002adde8270000)

libpthread.so.0 => /lib64/libpthread.so.0 (0x00000032f2600000)

libc.so.6 => /lib64/libc.so.6 (0x00000032f1a00000)

librt.so.1 => /lib64/librt.so.1 (0x00000032f2a00000)

/lib64/ld-linux-x86-64.so.2 (0x00000032f1600000)

四、监控
可以在服务器上配置一个PHP页面来监测Memcached的情况，
下载MemcachePHP



配置也比较简单，主要包括账户配置，以及Memcached Server地址配置。

define('ADMIN_USERNAME','memcache'); // Admin Username
define('ADMIN_PASSWORD','password'); // Admin Password
define('DATE_FORMAT','Y/m/d H:i:s');
define('GRAPH_SIZE',200);
define('MAX_ITEM_DUMP',50);

$MEMCACHE_SERVERS[] = 'mymemcache-server1:11211'; // add more as an array
$MEMCACHE_SERVERS[] = 'mymemcache-server2:11211'; // add more as an array

define('ADMIN_USERNAME','memcache'); 	// Admin Username
define('ADMIN_PASSWORD','password');  	// Admin Password
define('DATE_FORMAT','Y/m/d H:i:s');
define('GRAPH_SIZE',200);
define('MAX_ITEM_DUMP',50);

$MEMCACHE_SERVERS[] = 'mymemcache-server1:11211'; // add more as an array
$MEMCACHE_SERVERS[] = 'mymemcache-server2:11211'; // add more as an array

如果不方便搭建PHP服务，可以使用Perl脚本memcache-top
修改@default_instances或使用--instances参数：

perl memcache-top-v0.6 --instances 10.11.155.2610.11.155.41

perl memcache-top-v0.6 --instances 10.11.155.26 10.11.155.41

先到这里，后续做压力测试，Java客户端开发，Spring系统集成等。

相关链接：
Memcached笔记——（二）XMemcached&Spring集成


启动脚本 http://pastebin.com/wH7WQUra http://dngood.blog.51cto.com/446195/703347