Mysql resource temporarily unavailable

Question

I\'m seeing a few of these errors during high load times:

mysql_connect() [function.mysql-connect]: [2002]         


        

Answer 1

Geez, this could be so many things. It could be that the socket buffer space is exhausted. It could be that mysql is not accepting connections as fast as they are coming in and the backlog limit is reached (though I'd expect that to give you a "Connection Refused" error, I don't know for sure that's what you'll get for a Unix domain socket). It could be any of the things @MrGomez pointed out.

Since you are running Apache and MySQL on the same server and this is a problem under high load, it could well be that Apache is starving the system of some resource and you're just not seeing (noticing?) the dropped/failed incoming connections/requests in your logs.

Are you using connection pooling? If not, I'd start there.

I'd also look for errors in the Apache logs and syslog around the same time as the mysql_connect error and see what else turns up. I'd especially recommend getting MySQL moved over to its own separate dedicated server.