I few days ago I came across this report in the MySQL bug reporting system:
http://bugs.mysql.com/bug.php?id=12702
well .. it's not really a bug. But I guess we have all experienced that long running query on 'localhost' “kills” everything so that the computer can't be used for anything else. Reason is that the query proces has a priority of “high” or in numerical terms “8”. Normal priority is “6”. Only very critical system tasks have “9” .
There is a simple setting to give a query proces “normal” priority, as described in the bug report. The setting can be set from “MySQL Administrator” .. Startup variables .. Advanced
I have changed my setting!