Redis exception read error on connection solution

One 、 Cause and scene ：

In the interface connection redis when , Used pconnect Conduct redis A long connection , stay Redis->auth() Exception thrown in ：

PHP Fatal error:  Uncaught exception 'RedisException' with message 'read error on connection' 

notes ： because php-fpm Reusability of connections , therefore , When it exists cgi Process Manager [ Such as php-fpm,spawn-cgi], Use pconnect Efficient than connect high . But because each persistent connection takes up memory , When there is a large amount of concurrency , It is likely to cause memory shortage
 

Two 、 Reasons for appearance

adopt pconnect Of redis Long connections are not actively released , Will always be Stay in php-fpm In progress , Waiting to complete the next requested task , Even if passed close Only to make the current php No more redis request , But it can't really close redis A long connection , Connections will still be reused in subsequent requests , until fpm End of process life cycle .

In this way, the following two situations will occur ：

1） reason 1 Using a disconnected connection

If this connection is broken , The next request may directly use the last disconnected connection , When php-fpm Process the next request reuse A disconnected connection may cause read error on connection It's abnormal , Here are phpredis Explanation of the source code ：

2） reason 2： Execution timeout

a） The timeout set by the client is too short ;

b） The client did not set the timeout , But the execution time of the server exceeds the default timeout setting

php There is a configuration item default_socket_timeout It means a  socket Connection timeout , The default is 60s, and phpredis The underlying connection of this extension redis It is used. socket, So when a connection is in 60 When not used within seconds , The next connection will throw this exception .

3、 ... and 、 Solution

1） If it's the reason 1：

Change long connection to short connection perhaps stay pconnect Add timeout in

$this->redis->pconnect($host, $port, 2);       //@todo 2 The connection timed out after seconds , A new long connection will be used 

2） If it's the reason 2： Modify timeout

( Not recommended ) programme 1：

php.ini Set in

default_socket_timeout = -1

And then restart php-fpm

programme 2：

Dynamic modification php.ini 

ini_set('default_socket_timeout', -1); //  No timeout 

programme 3：

Set up redis The timeout time of is no timeout ：

$this->redis->setOption(Redis::OPT_READ_TIMEOUT, -1);

Reference resources ：

read error on connection Analysis of two reasons for - SegmentFault Think no