[Dovecot] fork bomb?

Timo Sirainen tss at iki.fi
Sat Apr 7 11:01:14 EEST 2007

On 7.4.2007, at 6.31, Timothy Martin wrote:

> 	Apr  6 21:19:34 design1st dovecot: Temporary failure in creating  
> login processes, slowing down for now
> 	Apr  6 21:19:34 design1st dovecot: Created login processes  
> successfully, unstalling

Hmm. This should probably be changed so that it won't even try  
unstalling that fast..

> Eventually the entire server became unresponsive. Normally I  
> wouldn't even think of blaming dovecot, but the hosting tech  
> support said that when the checked out "top" there were crazy  
> amounts of imap processes (maybe they just aren't used to dovecot's  
> methods of dealing with logins etc) but they blamed "my imap server".

imap or imap-login? You can limit the max. number of imap processes  
from max_mail_processes setting and imap-login processes from  
login_max_processes_count. So by default it'll create max. 1024+128  
processes. If this is too much for your server then you can drop them  
to some more reasonable limits..

> Any way I can find out if it's really dovecot that's causing this?  
> I recognize it might not be a dovecot issue, but it's the only hint  
> i've got right now.

I guess the only way would be to find out how many imap processes  
really were running at that time, but there's no really easy way to  
do that. You'd have to be looking at the login/logout lines and  
figure it out based on them..

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