作者：zhanhailiang 日期：2014-12-14

简介

twemproxy，也叫nutcracker，是twtter开源的Redis和Memcache代理服务器。

功能

• Fast.
• Lightweight.
• Maintains persistent server connections.
• Keeps connection count on the backend caching servers low.
• Enables pipelining of requests and responses.
• Supports proxying to multiple servers.
• Supports multiple server pools simultaneously.
• Shard data automatically across multiple servers.
• Implements the complete memcached ascii and redis protocol.
• Easy configuration of server pools through a YAML file.
• Supports multiple hashing modes including consistent hashing and distribution.
• Can be configured to disable nodes on failures.
• Observability through stats exposed on stats monitoring port.
• Works with Linux, *BSD, OS X and Solaris (SmartOS)

安装

从官网下载安装包编译并安装：distribution tarball:

[root@~/software/nutcracker-0.3.0]# ./configure --prefix=/usr/local/nutcracker-0.3.0
[root@~/software/nutcracker-0.3.0]# make
[root@~/software/nutcracker-0.3.0]# make install
[root@~/software/nutcracker-0.3.0]# cp -R conf /usr/local/nutcracker-0.3.0
[root@~/software/nutcracker-0.3.0]# ln -s /usr/local/nutcracker-0.3.0 /usr/local/nutcracker
[root@~/software/nutcracker-0.3.0]# ln -s /usr/local/nutcracker/sbin/nutcracker /usr/local/bin/nutcracker

配置

twemproxy支持通过YAML语法配置，其支持的指令集如下：

• listen: The listening address and port (name:port or ip:port) for this server pool.
• hash: The name of the hash function. Possible values are:
  • one_at_a_time
  • md5
  • crc16
  • crc32 (crc32 implementation compatible with libmemcached)
  • crc32a (correct crc32 implementation as per the spec)
  • fnv1_64
  • fnv1a_64
  • fnv1_32
  • fnv1a_32
  • hsieh
  • murmur
  • jenkins
• hash_tag: A two character string that specifies the part of the key used for hashing. Eg "{}" or "$$".Hash tag enable mapping different keys to the same server as long as the part of the key within the tag is the same.
• distribution: The key distribution mode. Possible values are:
  • ketama
  • modula
  • random
• timeout: The timeout value in msec that we wait for to establish a connection to the server or receive a response from a server. By default, we wait indefinitely.
• backlog: The TCP backlog argument. Defaults to 512.
• preconnect: A boolean value that controls if nutcracker should preconnect to all the servers in this pool on process start. Defaults to false.
• redis: A boolean value that controls if a server pool speaks redis or memcached protocol. Defaults to false.
• server_connections: The maximum number of connections that can be opened to each server. By default, we open at most 1 server connection.
• auto_eject_hosts: A boolean value that controls if server should be ejected temporarily when it fails consecutively server_failure_limit times. See liveness recommendations for information. Defaults to false.
• server_retry_timeout: The timeout value in msec to wait for before retrying on a temporarily ejected server, when auto_eject_host is set to true. Defaults to 30000 msec.
• server_failure_limit: The number of conseutive failures on a server that would leads to it being temporarily ejected when auto_eject_host is set to true. Defaults to 2.
• servers: A list of server address, port and weight (name:port:weight or ip:port:weight) for this server pool.

以本文为例，配置一个Redis代理和一个Memcache代理服务如下：

[root@~/software/nutcracker-0.3.0]# cat /usr/local/nutcracker/conf/nutcracker.yml
alpha:
  listen: 127.0.0.1:22121
  hash: fnv1a_64
  hash_tag: "{}"
  distribution: ketama
  auto_eject_hosts: false
  timeout: 400
  redis: true
  servers:
   - 127.0.0.1:6379:1

beta:
  listen: 127.0.0.1:22122
  hash: fnv1a_64
  distribution: ketama
  timeout: 400
  backlog: 1024
  preconnect: true
  auto_eject_hosts: true
  server_retry_timeout: 2000
  server_failure_limit: 3
  servers:
   - 127.0.0.1:11211:1
   - 127.0.0.1:11212:1

其中，Redis实例 127.0.0.1:6379 和 Memcache实例 127.0.0.1:11211 127.0.0.1:11212 请预先启动好。

/etc/init.d/redis_6379 start
/usr/local/memcached-1.4.20/bin/memcached -d -m 64 -l 127.0.0.1 -p 11211 -u root
/usr/local/memcached-1.4.20/bin/memcached -d -m 64 -l 127.0.0.1 -p 11212 -u root

测试

https://github.com/billfeller/billfeller.github.io/blob/master/code/twenproxyTest.php

启动服务：

[root@/usr/local/nutcracker/conf]# nutcracker -c nutcracker.yml
[Sun Dec 14 20:59:04 2014] nc.c:187 nutcracker-0.3.0 built for Linux 2.6.32-431.23.3.el6.x86_64 x86_64 started on pid 14359
[Sun Dec 14 20:59:04 2014] nc.c:192 run, rabbit run / dig that hole, forget the sun / and when at last the work is done / don‘t sit down / it‘s time to dig another one

执行测试脚本：

[root@~/wade/git/billfeller.github.io/code]# /usr/local/php/bin/php twenproxyTest.php 
bool(true)
string(1) "1"
int(1)
bool(false)
bool(true)
int(2)
bool(true)
int(3)
bool(true)
bool(false)

Redis/Memcache代理服务Twemproxy简介