MySQL - How to diagnose the reason for the warning "Interrupted connection - (Got a timeout reading communication packets)"

Question

I am having problems on our rather busy Windows 2008 R2 web server running under MySQL.

Applications are interrupted, and logs usually point to MySQL as the cause of the route, because applications cannot connect to MySQL. This does not affect all users, only a few unsuccessful ones.

When I enable message logging in MySQL, I see duplicate logs of the following warning:

[Warning] Aborted connection 7153 to db user: 'XXXX' host: 'XXXXXX' (Got timeout reading communication packets) 

The docs here http://dev.mysql.com/doc/refman/5.0/en/communication-errors.html offer a number of potential network-related reasons.

Some configuration in the "Advanced Network" section:

Maximum packet size: 128 M (we increased this from 64 M yesterday) Waiting time: 20 Max. Connections: 1000 Max Conn per: 1000 Repeats: 5

My question is: what is the best way to diagnose the cause of this problem, and not just play with the settings and wait?

Thanks in advance

Answer 1

This was a difficult problem to solve, but in the end we found that several thousand apparently lost TCP connections were opened (using the Task Manager> Resource Monitor), which was generated by the email sending process.

Since MySQL connections are TCP dependent, the db server was affected as a result.