[Dovecot] MySQL server has gone away

[Timo Sirainen]

On 13.1.2012, at 4.00, Mark Moseley wrote:

> I'm running 2.0.17 and I'm still seeing a decent amount of "MySQL
> server has gone away" errors, despite having multiple hosts defined in
> my auth userdb 'connect'. This is Debian Lenny 32-bit and I'm seeing
> the same thing with 2.0.16 on Debian Squeeze 64-bit.
> 
> E.g.:
> 
> Jan 12 20:30:33 auth-worker: Error: mysql: Query failed, retrying:
> MySQL server has gone away
> 
> Our mail mysql servers are busy enough that wait_timeout is set to a
> whopping 30 seconds. On my regular boxes, I see a good deal of these
> in the logs. I've been doing a lot of mucking with doveadm/dsync
> (working on maildir->mdbox migration finally, yay!) on test boxes
> (same dovecot package & version) and when I get this error, despite
> the log saying it's retrying, it doesn't seem to be. Instead I get:
> 
> dsync(root): Error: user ...: Auth USER lookup failed

Try with only one host in the "connect" string? My guess: Both the connections have timed out, and the retrying fails as well (there is only one retry). Although if the retrying lookup fails, there should be an error logged about it also (you don't see one?)

Also another idea to avoid them in the first place:

service auth-worker {
  idle_kill = 20
}