Redis

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参考地址:http://snowolf.iteye.com/blog/1630697

Redis简要介绍

Redis —— REmote DIctionary Server,可以直接理解为远程字典服务,也就是基于Key-Value模式Memcached+Database Persistence。


使用Memcached,让我感触颇深的是Object Size的问题,由于SQL未作优化直接映射对象,导致缓存对象大于1MB,Memcached就抛了异常。而Redis默认缓存对象512MB,最大支持1GB。至少在缓存对象时,可以有更大的伸缩空间了! 此外,是数据类型。Memcached比较简单,而Redis可以支持更多复杂的数据类型,如HASH、SET、SortedSet等等。

PS:Memcached是在Server端实现的ShardingRedis没有对应的实现,

安装

下载redis, “configure”文件都不需要,你只需要做个“make”.Redis可以解压至任何目录,一个make安装即可获得执行、配置文件.

make之后,我们会得到以下可执行文件:

  • redis-server:Redis服务器的daemon启动程序
  • redis-cli:Redis命令行操作工具。或者通过telnet进行纯文本协议操作
  • redis-benchmark:Redis性能测试工具,测试Redis在你的系统及你的配置下的读写性能


上述文件位于src目录下。

我习惯性的执行了make install,貌似我需要的可执行文件,安装到了/usr/local/bin

引用

# make install
cd src && make install
make[1]: Entering directory `/opt/software/redis-2.4.16/src'
MAKE hiredis
make[2]: Entering directory `/opt/software/redis-2.4.16/deps/hiredis'
make[2]: Nothing to be done for `static'.
make[2]: Leaving directory `/opt/software/redis-2.4.16/deps/hiredis'
MAKE linenoise
make[2]: Entering directory `/opt/software/redis-2.4.16/deps/linenoise'
make[2]: “linenoise_example”是最新的。
make[2]: Leaving directory `/opt/software/redis-2.4.16/deps/linenoise'
MAKE hiredis
make[2]: Entering directory `/opt/software/redis-2.4.16/deps/hiredis'
make[2]: Nothing to be done for `static'.
make[2]: Leaving directory `/opt/software/redis-2.4.16/deps/hiredis'
    LINK redis-benchmark
    LINK redis-cli

Hint: To run 'make test' is a good idea ;)

mkdir -p /usr/local/bin
cp -pf redis-server /usr/local/bin
cp -pf redis-benchmark /usr/local/bin
cp -pf redis-cli /usr/local/bin
cp -pf redis-check-dump /usr/local/bin
cp -pf redis-check-aof /usr/local/bin
make[1]: Leaving directory `/opt/software/redis-2.4.16/src'


这样,就不用我拷贝文件了。意外收获!

此外,还会得到一个默认的配置文件——redis.conf
最好,把它拷贝到固定的目录下,例如:/etc/redis/目录下!

 mkdir /etc/redis
cp redis.conf /etc/redis 

然后,我们就可以在任何路径下,直接启动Redis了

三、运行

运行Redis:

redis-server /etc/redis/redis.conf

引用
[1958] 13 Aug 16:18:24 * Server started, Redis version 2.4.16
[1958] 13 Aug 16:18:24 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
[1958] 13 Aug 16:18:24 * The server is now ready to accept connections on port 6379
[1958] 13 Aug 16:18:24 - 0 clients connected (0 slaves), 717544 bytes in use

四、测试

通过客户端命令redis-cli访问Redis

引用
# redis-cli 
    redis> set name zlex 
    OK 
    redis> get name  
    "zlex" 

 

进行数据测试:redis-benchmark -l  

 这个测试会一直进行下去,直到你Ctrl+C:


====== PING (inline) ======
10000 requests completed in 0.12 seconds
50 parallel clients
3 bytes payload
keep alive: 1

99.31% <= 1 milliseconds
99.53% <= 2 milliseconds
99.64% <= 3 milliseconds
99.70% <= 4 milliseconds
99.74% <= 5 milliseconds
99.78% <= 6 milliseconds
99.82% <= 7 milliseconds
99.84% <= 8 milliseconds
99.86% <= 9 milliseconds
99.89% <= 10 milliseconds
99.91% <= 11 milliseconds
99.93% <= 12 milliseconds
99.96% <= 13 milliseconds
99.98% <= 14 milliseconds
100.00% <= 15 milliseconds
81300.81 requests per second

====== PING ======
10000 requests completed in 0.12 seconds
50 parallel clients
3 bytes payload
keep alive: 1

99.96% <= 1 milliseconds
100.00% <= 1 milliseconds
84033.61 requests per second

^CET (10 keys): 26200.00

五、关闭

也可通过客户端命令redis-cli完成Redis关闭操作

redis-cli shutdown    

引用
[2639] 13 Aug 16:35:35 # User requested shutdown...
[2639] 13 Aug 16:35:35 * Saving the final RDB snapshot before exiting.
[2639] 13 Aug 16:36:49 * DB saved on disk
[2639] 13 Aug 16:36:49 # Redis is now ready to exit, bye bye...

六、调优


1./etc/sysctl.conf
前面启动Redis时,看到如下警告:

引用
[1958] 13 Aug 16:18:24 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.


需要修改/etc/sysctl.conf文件:

 

Shell代码 复制代码 收藏代码
  1. vim /etc/sysctl.conf  

  

末尾追加vm.overcommit_memory = 1
然后执行sysctl vm.overcommit_memory=1,使之生效:

 

Shell代码 复制代码 收藏代码
  1. # sysctl vm.overcommit_memory=1  
  2. vm.overcommit_memory = 1  

  

2./proc/sys/vm/overcommit_memory
为了调整内存分配策略,需要配置/proc/sys/vm/overcommit_memory

  • 0, 表示内核将检查是否有足够的可用内存供应用进程使用;如果有足够的可用内存,内存申请允许;否则,内存申请失败,并把错误返回给应用进程。
  • 1, 表示内核允许分配所有的物理内存,而不管当前的内存状态如何。
  • 2, 表示内核允许分配超过所有物理内存和交换空间总和的内存


默认为0,如果内存情况比较紧张的话,设为1:

 

Shell代码 复制代码 收藏代码
  1. echo 1 > /proc/sys/vm/overcommit_memory  

 3.redis.conf

前面启动Redis后,总是在命令行里不断跳着各种日志,很麻烦。即便通过“&”,领其后台运行,也无济于事。这就需要修改redis.conf,以Daemo模式运行!redis.conf参数:•daemonize:是否以后台daemon方式运行•pidfile:pid文件位置•port:监听的端口号•timeout:请求超时时间•loglevel:log信息级别•logfile:log文件位置•databases:开启数据库的数量•save * *:保存快照的频率,第一个*表示多长时间(秒级),第三个*表示执行多少次写操作。在一定时间内执行一定数量的写操作时,自动保存快照。可设置多个条件。•rdbcompression:是否使用压缩•dbfilename:数据快照文件名(只是文件名,不包括目录)•dir:数据快照的保存目录(这个是目录)•appendonly:是否开启appendonlylog,开启的话每次写操作会记一条log,这会提高数据抗风险能力,但影响效率。•appendfsync:appendonlylog如何同步到磁盘(三个选项,分别是每次写都强制调用fsync、每秒启用一次fsync、不调用fsync等待系统自己同步)•slaveof <masterip> <masterport> :主从配置,在redis-slave上配置master的ip port,即可。

例如,我们可以修改为如下方式:

引用
daemonize yes #守护进程模式
save 60 1000 #当时间间隔超过60秒,或存储超过1000条记录时,进行持久化。
maxmemory 256mb #分配256MB内存

 

PS:切记,一定要设定maxmemmory,且配置大小要小于物理内存,留有足够的内存供系统使用。

 

公司的Redis,某期间数据暴涨,导致内存吃紧,SWAP加剧,直接宕机。就是因为没有设置maxmemmory



七、集群配置

把鸡蛋都放在一个篮子里是件危险的事情。首先,要做好主备。其次,如果可以做一致性哈希,可以起到负载均衡的作用。


配置Master-Slave,只需要在Slave上配置Master节点IP Port:

 

 这里的Master IP 为192.168.133.139 端口位6379,配置redis.conf:
slaveof 192.168.133.139 6379

PS:为了两个Redis Server可以互访,需要注释掉bind 127.0.0.1

 

依次启动Master,Slave:

 

 Master
[7651] 17 Aug 19:08:07 * Server started, Redis version 2.4.16
[7651] 17 Aug 19:08:07 * DB loaded from disk: 0 seconds
[7651] 17 Aug 19:08:07 * The server is now ready to accept connections on port 6379
[7651] 17 Aug 19:08:08 * Slave ask for synchronization
[7651] 17 Aug 19:08:08 * Starting BGSAVE for SYNC
[7651] 17 Aug 19:08:08 * Background saving started by pid 7652
[7652] 17 Aug 19:08:08 * DB saved on disk
[7651] 17 Aug 19:08:08 * Background saving terminated with success
[7651] 17 Aug 19:08:08 * Synchronization with slave succeeded

 

 

 Slave
[7572] 17 Aug 19:07:39 * Server started, Redis version 2.4.16
[7572] 17 Aug 19:07:39 * DB loaded from disk: 0 seconds
[7572] 17 Aug 19:07:39 * The server is now ready to accept connections on port 6379
[7572] 17 Aug 19:07:39 * Connecting to MASTER...
[7572] 17 Aug 19:08:08 * MASTER <-> SLAVE sync started: SYNC sent
[7572] 17 Aug 19:08:08 * MASTER <-> SLAVE sync: receiving 10 bytes from master
[7572] 17 Aug 19:08:08 * MASTER <-> SLAVE sync: Loading DB in memory
[7572] 17 Aug 19:08:08 * MASTER <-> SLAVE sync: Finished with success

 

看到上述日志,就说明Master-Slave已经连通。

 

简单测试,Master写,Slave读:

 

 Master写
telnet 192.168.133.139 6379
Trying 192.168.133.139...
Connected to 192.168.133.139.
Escape character is '^]'.
set name snowolf
+OK

 

 

Slave读 
telnet 192.168.133.140 6379
Trying 192.168.133.140...
Connected to 192.168.133.140.
Escape character is '^]'.
get name
$7
snowolf


 

八、主从备份

在从服务器上执行下列命令:

Shell代码 复制代码 收藏代码
  1. #备份   
  2. redis-cli save   
  3.   
  4. #关闭redis服务器   
  5. redis-cli shutdown  

 然后,拷贝数据目录下的rdb文件。

九、系统服务

习惯了通过service启动一切服务,当然,这跟我生产环境部署有关,通常只分配给用于部署的账户操作service命令的权限。主要是为了确保系统安全。

参考之前写的Memcached的系统服务文件,改造一个Redis版本!

新建文件,并赋予权限:

  1. touch /etc/init.d/redis-server   
  2. chmod +x /etc/init.d/redis-server  
编辑/etc/init.d/redis-server,键入如下内容:

#!/bin/bash## redis    Startup script for redis processes## author: snowolf## processname: redisredis_path="/usr/local/bin/redis-server"redis_conf="/etc/redis/redis.conf"redis_pid="/var/run/redis.pid"# Source function library.. /etc/rc.d/init.d/functions[ -x $redis_path ] || exit 0RETVAL=0prog="redis"# Start daemons.start() {    if [ -e $redis_pid -a ! -z $redis_pid ];then        echo $prog" already running...."        exit 1    fi    echo -n $"Starting $prog "    # Single instance for all caches    $redis_path $redis_conf    RETVAL=$?    [ $RETVAL -eq 0 ] && {        touch /var/lock/subsys/$prog        success $"$prog"    }    echo    return $RETVAL}# Stop daemons.stop() {    echo -n $"Stopping $prog "    killproc -d 10 $redis_path    echo    [ $RETVAL = 0 ] && rm -f $redis_pid /var/lock/subsys/$prog    RETVAL=$?    return $RETVAL}# See how we were called.case "$1" in        start)            start            ;;        stop)            stop            ;;        status)            status $prog            RETVAL=$?            ;;        restart)            stop            start            ;;        condrestart)            if test "x`pidof redis`" != x; then                stop                start            fi            ;;        *)            echo $"Usage: $0 {start|stop|status|restart|condrestart}"            exit 1esacexit $RETVAL

引用
# service redis-server restart
Stopping redis                                             [失败]
Starting redis                                             [确定]
# service redis-server status
redis (pid  14965) 正在运行...


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