memcached演练(1) 搭建memcached服务
memcached已经火了好多年了，现在网上关于memcached的资源相当多了，我就不浪费话语了。干脆写一个实战系列，坚持一切用实施说话。环境介绍
Linux虚拟机
内核信息
# uname -a
Linux hadoop1 2.6.32-358.el6.i686
内存：1G
安装过程
1.准备编译环境，安装必须的gcc，make工具，如果没有安装yum，最好安装下。网上有很多共享的yum源。
2.下载最新版本的libevent
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# wget https://github.com/libevent/libevent/releases/download/release-2.0.22-stable/libevent-2.0.22-stable.tar.gz
3.解压libevent对应压缩包
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# tar zxvf libevent-2.0.22-stable.tar.gz
解压之后的文件路径：/u01/software/libevent-2.0.22-stable
3.编译libevent
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$ cd /u01/software/libevent-2.0.22-stable
$./configure -prefix=/usr/local/libevent
$ make
$ make install
确认安装结果
$ ls -al /usr/local/lib |grep libevent
4.下载最新版本的memcached
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$ wget http://memcached.org/latest
5.解压memcached对应压缩包
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$ tar zxvf memcached-1.4.29.tar.gz
解压之后的文件路径：/u01/software/memcached-1.4.29
6.编译memcached
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$ cd /u01/software/memcached-1.4.29
$ # ./configure-help
`configure' configures memcached 1.4.29 to adapt to many kinds of systems.
Usage: ./configure ... ...
Configuration:
-h, --help display this help and exit
--help=short display options specific to this package
--help=recursive display the short help of all the included packages
-V, --version display version information and exit
-q, --quiet, --silent do not print `checking ...' messages
--cache-file=FILE cache test results in FILE
-C, --config-cache alias for `--cache-file=config.cache'
-n, --no-create do not create output files
--srcdir=DIR find the sources in DIR
Installation directories:
--prefix=PREFIX install architecture-independent files in PREFIX
...
Fine tuning of the installation directories:
--bindir=DIR user executables
--sbindir=DIR system admin executables
--libexecdir=DIR program executables
--sysconfdir=DIR read-only single-machine data
--sharedstatedir=DIR modifiable architecture-independent data
--localstatedir=DIR modifiable single-machine data
--libdir=DIR object code libraries
--includedir=DIR C header files
--oldincludedir=DIR C header files for non-gcc
--datarootdir=DIR read-only arch.-independent data root
--datadir=DIR read-only architecture-independent data
--infodir=DIR info documentation
--localedir=DIR locale-dependent data
--mandir=DIR man documentation
--docdir=DIR documentation root
--htmldir=DIR html documentation
--dvidir=DIR dvi documentation
--pdfdir=DIR pdf documentation
--psdir=DIR ps documentation
Optional Packages:
--with-PACKAGE[=ARG] use PACKAGE
--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)
--with-libevent=PATH Specify path to libevent installation
# ./configure --prefix=/usr/local/memcached--with-libevent=/usr/local/lib/
# make
# make install
这时候memcached安装成功了
启动memcached
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$ /usr/local/memcached/bin/memcached 报错
error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory
解决思路
##跟踪运行memcached所有加载库文件的路径
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$ LD_DEBUG=libs LD_DEBUG=libs ./memcached -v
15862: find library=libevent-2.0.so.5 ; searching
15862: search cache=/etc/ld.so.cache
15862: search path=/lib/tls/i686/sse2:/lib/tls/i686:/lib/tls/sse2:/lib/tls:/lib/i686/sse2:/lib/i686:/lib/sse2:/lib:/usr/lib/tls/i686/sse2:/usr/lib/tls/i686:/usr/lib/tls/sse2:/usr/lib/tls:/usr/lib/i686/sse2:/usr/lib/i686:/usr/lib/sse2:/usr/lib (system search path)
15862: trying file=/lib/tls/i686/sse2/libevent-2.0.so.5
15862: trying file=/lib/tls/i686/libevent-2.0.so.5
15862: trying file=/lib/tls/sse2/libevent-2.0.so.5
15862: trying file=/lib/tls/libevent-2.0.so.5
15862: trying file=/lib/i686/sse2/libevent-2.0.so.5
15862: trying file=/lib/i686/libevent-2.0.so.5
15862: trying file=/lib/sse2/libevent-2.0.so.5
15862: trying file=/lib/libevent-2.0.so.5
...
首先确认建立软连接
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$ ls /usr/local/lib/libevent-2.0.so.5
/usr/local/lib/libevent-2.0.so.5
$ ln -s /usr/local/lib/libevent-2.0.so.5 /usr/lib/i686/libevent-2.0.so.5
如果以root用户登陆，必须指定-u参数
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$ /usr/local/memcached/bin/memcached-u hadoop
确认memcached是否启动成功
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$ ps -ef |grep memcached
hadoop 1589140340 22:45 pts/4 00:00:00 /usr/local/memcached/bin/memcached -u hadoop
root 15899 155610 22:45 pts/5 00:00:00 grep memcached
# netstat -tlnp |grep memcached
tcp 0 0 0.0.0.0:11211 0.0.0.0:* LISTEN 15891/memcached
tcp 0 0 :::11211 :::* LISTEN 15891/memcached
最后telnet 确认下
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$ telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
stats
STAT pid 15891
STAT uptime 86
STAT time 1470494793
OK。至此memcached1.4.9版本已经成功在机器上安装。个人感觉最麻烦的地方，就是处理libevent。
参考了很多资源，才把问题解决。
memcached设置自启动
为了方便，现将memcached执行变更下权限
[*]最简单的启动方式
只需在/etc/rc.d/rc.local中加入一行
/usr/local/memcached/bin/memcached -d -m 20 -p 11211 -u hadoop
注意
-d：设置为后台进程
-u：指向用户
-p:端口
-m:内存
[*]推荐的方式
2.1.拷贝memcached源码包的memcached.sysv拷贝到/etc/init.d，做为memcached的启动脚本
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$ cp /u01/software/memcached-1.4.29/scripts/memcached.sysv/etc/init.d/memcached
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# vi /etc/init.d/memcached
#! /bin/sh
#
# chkconfig: - 55 45
# description:The memcached daemon is a network memory cache service.
# processname: memcached
# config: /etc/sysconfig/memcached
# Source function library.
. /etc/rc.d/init.d/functions
PORT=11211
USER=nobody
MAXCONN=1024
CACHESIZE=64
OPTIONS=""
if [ -f /etc/sysconfig/memcached ];then
. /etc/sysconfig/memcached
fi
# Check that networking is up.
if [ "$NETWORKING" = "no" ]
then
exit 0
fi
RETVAL=0
prog="memcached"
start () {
echo -n $"Starting $prog: "
# insure that /var/run/memcached has proper permissions
chown $USER /var/run/memcached
daemon memcached -d -p $PORT -u $USER-m $CACHESIZE -c $MAXCONN -P /var/run/memcached/memcached.pid $OPTIONS
RETVAL=$?
echo
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/memcached
}
stop () {
echo -n $"Stopping $prog: "
killproc memcached
RETVAL=$?
echo
if [ $RETVAL -eq 0 ] ; then
rm -f /var/lock/subsys/memcached
rm -f /var/run/memcached/memcached.pid
fi
}
restart () {
stop
start
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
status)
status memcached
;;
restart|reload)
restart
;;
condrestart)
[ -f /var/lock/subsys/memcached ] && restart || :
;;
*)
echo $"Usage: $0 {start|stop|status|restart|reload|condrestart}"
exit 1
esac
exit $?
修改下面这一句（其实就将memcached 命令指向咱们的全路径）
daemon memcached -d -p $PORT -u $USER-m $CACHESIZE -c $MAXCONN -P /var/run/memcached/memcached.pid $OPTIONS
daemon/usr/local/memcached/bin/memcached-d -p $PORT -u $USER-m $CACHESIZE -c $MAXCONN -P /var/run/memcached/memcached.pid $OPTIONS
配置自启动
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$ chkconfig memcached on
$ chkconfig |grep memcached
memcached 0:off 1:off 2:on 3:on 4:on 5:on 6:off
安装nc
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$ yum install nc
memcached 自带的stats命令，对搜索不太友好。为了很好的搜索，借助nc工具。
比如，想查找connection相关的参数
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# echo stats | nc 127.0.0.1 11211 |grep connection
STAT curr_connections 10
STAT total_connections 13
STAT connection_structures 11
配合nc使用形式，个人参考网上资源，简单罗列下
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watch "echo stats | nc 127.0.0.1 11211"
printf "stats\r\n" | nc 127.0.0.1 11211
echo stats | nc 127.0.0.1 11211
------------------------------------------------------------
The End
接下来，演练的内容是通过telnet命令行和JAVA 客户端工具，访问memcachd.
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