memcached演练(1) 搭建memcached服务

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　　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

　　[root@hadoop1 ~]# 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
# 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
# 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
$ 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
$ wget http://memcached.org/latest　　5.解压memcached对应压缩包
$ 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
$ cd /u01/software/memcached-1.4.29
$ [root@hadoop1 memcached-1.4.29]# ./configure  -help
`configure' configures memcached 1.4.29 to adapt to many kinds of systems.
Usage: ./configure [OPTION]... [VAR=VALUE]...
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 [disabled]
  -C, --config-cache      alias for `--cache-file=config.cache'
  -n, --no-create         do not create output files
      --srcdir=DIR        find the sources in DIR [configure dir or `..']
Installation directories:
  --prefix=PREFIX         install architecture-independent files in PREFIX
                          [/usr/local]
...
Fine tuning of the installation directories:
  --bindir=DIR            user executables [EPREFIX/bin]
  --sbindir=DIR           system admin executables [EPREFIX/sbin]
  --libexecdir=DIR        program executables [EPREFIX/libexec]
  --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
  --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
  --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
  --libdir=DIR            object code libraries [EPREFIX/lib]
  --includedir=DIR        C header files [PREFIX/include]
  --oldincludedir=DIR     C header files for non-gcc [/usr/include]
  --datarootdir=DIR       read-only arch.-independent data root [PREFIX/share]
  --datadir=DIR           read-only architecture-independent data [DATAROOTDIR]
  --infodir=DIR           info documentation [DATAROOTDIR/info]
  --localedir=DIR         locale-dependent data [DATAROOTDIR/locale]
  --mandir=DIR            man documentation [DATAROOTDIR/man]
  --docdir=DIR            documentation root [DATAROOTDIR/doc/memcached]
  --htmldir=DIR           html documentation [DOCDIR]
  --dvidir=DIR            dvi documentation [DOCDIR]
  --pdfdir=DIR            pdf documentation [DOCDIR]
  --psdir=DIR             ps documentation [DOCDIR]
  Optional Packages:
  --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
  --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
$ /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

$ LD_DEBUG=libs LD_DEBUG=libs ./memcached -v
     15862:     find library=libevent-2.0.so.5 [0]; 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

$ 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
$ /usr/local/memcached/bin/memcached  -u hadoop　　确认memcached是否启动成功
$ ps -ef |grep memcached
hadoop   15891  4034  0 22:45 pts/4    00:00:00 /usr/local/memcached/bin/memcached -u hadoop
root     15899 15561  0 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
$ 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
$ cp /u01/software/memcached-1.4.29/scripts/memcached.sysv  /etc/init.d/memcached[root@hadoop1 bin]# 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
[root@hadoop1 bin]$ chkconfig memcached on
[root@hadoop1 bin]$ chkconfig |grep memcached
memcached       0:off   1:off   2:on    3:on    4:on    5:on    6:off　　

　　安装nc

[root@hadoop1 yum.repos.d]$ 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

[root@hadoop1 yum.repos.d]# 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
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.