redis属于单进程的服务，它主要受内存、CPU、磁盘IO（主要是做持久化），如果服务器配置比较高，多核CPU、高内存的服务器，可以考虑做redis多实例。做多实例之前，首先要考虑CPU和内存的利用，我在测试的时候发现，redis在QPS为6-8W左右的时候，这个redis所在的逻辑CPU核的负载就在100%左右，所以要优化CPU使用这块，目前一般是是做网卡软中断来实现平衡这种单进程使用CPU过高的情况，不过需要网卡支持网卡软中断，效果不错。

   多实例redis的管理，涉及到监控、服务的管理等，这里只说redis多实例的重启。以下是多实例的重启脚本，仅供交流参考：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import redis,threading,sys,socket,time,os
from multiprocessing import Pool
def port_check(host,port):
    POOL = redis.ConnectionPool(host=host, port=port)
    my_server = redis.Redis(connection_pool=POOL)
    try:
        a = my_server.ping()
        if a:
            return 1
        else:
            return 0
    except Exception,e:
        return 0
def shutdown_server(host,port):
    flag = port_check(host,port)
    if flag == 1:
        POOL = redis.ConnectionPool(host=host, port=port)
        my_server = redis.Redis(connection_pool=POOL)
        my_server.shutdown()
        while 1:
            flag = port_check(host,port)
            if flag == 0:
                print "%s:%s is Shutdown OK" % (host,port)
                break
            else:
                time.sleep(1)
    else:
        print "%s:%s is Shutdown alreaday" % (host,port)
def start_server(host,port):
    flag = port_check(host,port)
    if flag == 0:
        start_conm = "/usr/local/bin/redis-server /usr/local/redis/etc/redis_%s.conf" % port
        os.popen(start_conm)
        time.sleep(3)
        i = 0
        while 1:#每5s检测一次redis ping,持续一分钟，1分钟没有起来认为启动失败
            flag = port_check(host,port)
            if flag == 1:
                print "%s:%s is Start OK" % (host,port)
                break
            else:
                if i > 12:
                    print "%s:%s is Start Error" % (host,port)
                    break
                else:
                    time.sleep(5)
                    i = i + 1
    else:
        print "%s:%s is Start alreaday" % (host,port)
def restart(host,port):
    shutdown_server(host,port)
    start_server(host,port)
def main():
    server_list = ["127.0.0.1:6379","127.0.0.1:16379"]
    pool = Pool(processes=3)
    for i in server_list:
        aa = i.split(':')
        host = aa[0]
        port = int(aa[1])
        results = pool.apply_async(restart, (host,port))
    pool.close()
    pool.join()
    if results.successful():
        print 'successful'
if __name__=="__main__":
    main()