Redis中connect与pconnect区别？

1.首先先介绍下connect和pconnect的区别。

connect：脚本结束之后连接就释放了。

2.pconnect：脚本结束之后连接不释放，连接保持在php-fpm进程中。

所以使用pconnect代替connect，可以减少频繁建立redis连接的消耗。

redis手册中的介绍

1. connect, open
   
2. Description
   

   Connects to a Redis instance.

   连接到一个Redis实例

3. Parameters
   

   host: string. can be a host, or the path to a unix domain socket
   host:字符串类型
   可以使一个HOST IP或者是一个UNIX DOMAIN SOCKET的路径
   
   即连接没有时间限制

4. Return Value
   

   BOOL: TRUE on success, FALSE on error.

5. Example
   

   $redis->connect('127.0.0.1', 6379);

   $redis->connect('127.0.0.1'); // port 6379 by default

   $redis->connect('127.0.0.1', 6379, 2.5); // 2.5 sec timeout.

   $redis->connect('/tmp/redis.sock'); // unix domain socket.

1. pconnect, popen

1. Description
   

   Connects to a Redis instance or reuse a connection already established with pconnect/popen.
   
   pconnect/popen用于连接一个Redis的实例或者复用一个已经存在的实例。

   The connection will not be closed on close or end of request until the php process ends. So be patient on to many open FD's (specially on redis server side) when using persistent connections on many servers connecting to one redis server.

   这个连接将不会被主动关闭，比如使用close()，或者PHP执行结束这个连接都不会被主动关闭。当有大量的connect请求在redis服务器端时，使用持久化的连接对象。

   Also more than one persistent connection can be made identified by either host + port + timeout or host + persistent_id or unix socket + timeout.

   一个持久化的连接实例，可以使用HOST+PORT+TIMEOUT或者HOST+persistent_id或者SOCKET+TIMEOUT的方式创建。

   This feature is not available in threaded versions. pconnect and popen then working like their non persistent equivalents.

   pconnect函数和popen函数在线程版本中不能被使用。

2. Parameters
   

   host: string. can be a host, or the path to a unix domain socket
   port: int, optional
   timeout: float, value in seconds (optional, default is 0 meaning unlimited)
   persistent_id: string. identity for the requested persistent connection

3. Return Value
   

   BOOL: TRUE on success, FALSE on error.

4. Example
   

   $redis->pconnect('127.0.0.1', 6379);

   $redis->pconnect('127.0.0.1'); // port 6379 by default - same connection like before.

   $redis->pconnect('127.0.0.1', 6379, 2.5); // 2.5 sec timeout and would be another connection than the two before.

   $redis->pconnect('127.0.0.1', 6379, 2.5, 'x'); // x is sent as persistent_id and would be another connection the the three before.

   $redis->pconnect('/tmp/redis.sock'); // unix domain socket - would be another connection than the four before.