dovecot - Feb 2009 - help: "dovecot: pipe() failed: Too many open files"

Dear All,

I'm having an intermittent problem, with dovecot slowing to a crawl. 
Restarting dovecot fixes the problem.

Looking at the maillog, I see loads of these errors....

dovecot: pipe() failed: Too many open files
dovecot: Temporary failure in creating login processes, slowing down for now
dovecot: Created login processes successfully, unstalling

looking at the processes, I can see ~200 imap-login's and about ~700
imap's
there are 1000 email accounts on the server - half of which are in regular 
use.

The server is Dell PE1950 running dovecot (1.0.7-2.el5) as supplied with 
Centos 5.2 (~Redhat AS 5.2) in 64 bit mode. I've upgraded the server from 4 
to 8GB of RAM, and from a dual core 1.5Ghz xeon, to a quad core 1.5GHz xeon, 
and this does not seem to help.

The following settings were increased by me to try and stop this problem - but 
did not have an obvious effect:

login_process_size = 128
login_process_per_connection = yes
login_max_processes_count = 512

Other parameters were left commented out:

#max_mail_processes = 1024
#auth_process_size = 256


If anyone has any ideas about where I might be going wrong, please let me 
know..!

many thanks

Jake

-- 
Dr Jake Grimmett
Head Of Scientific Computing
MRC Laboratory of Molecular Biology
Hills Road, Cambridge, CB2 0QH, UK.
Phone 01223 402219
Mobile 0776 9886539

I reported a bug like this on 23rd Dec last year and Timo replied 8/1
this year. However, I've seen this bug very infrequently and I'm not
sure that you're hitting it - it's more likely that your ulimit -n is
too low - try setting it to around 8192 (defaults to 1024 I think). It
should be around 3* max conns you expect to be on the safe side of
things.

Mark

--
Mark Zealey -- Shared Hosting Team Leader
Product Development * Webfusion
123-reg.co.uk, webfusion.co.uk, donhost.co.uk, supanames.co.uk

This mail is subject to http://www.gxn.net/disclaimer 
> -----Original Message-----
> From: dovecot-bounces+mark.zealey=webfusion.com at dovecot.org 
> [mailto:dovecot-bounces+mark.zealey=webfusion.com at dovecot.org]
>  On Behalf Of Jake Grimmett
> Sent: 06 February 2009 15:15
> To: dovecot at dovecot.org
> Subject: [Dovecot] help: "dovecot: pipe() failed: Too many open
files"
> 
> Dear All,
> 
> I'm having an intermittent problem, with dovecot slowing to a crawl. 
> Restarting dovecot fixes the problem.
> 
> Looking at the maillog, I see loads of these errors....
> 
> dovecot: pipe() failed: Too many open files
> dovecot: Temporary failure in creating login processes, 
> slowing down for now
> dovecot: Created login processes successfully, unstalling
> 
> looking at the processes, I can see ~200 imap-login's and 
> about ~700 imap's
> there are 1000 email accounts on the server - half of which 
> are in regular 
> use.
> 
> The server is Dell PE1950 running dovecot (1.0.7-2.el5) as 
> supplied with 
> Centos 5.2 (~Redhat AS 5.2) in 64 bit mode. I've upgraded the 
> server from 4 
> to 8GB of RAM, and from a dual core 1.5Ghz xeon, to a quad 
> core 1.5GHz xeon, 
> and this does not seem to help.
> 
> The following settings were increased by me to try and stop 
> this problem - but 
> did not have an obvious effect:
> 
> login_process_size = 128
> login_process_per_connection = yes
> login_max_processes_count = 512
> 
> Other parameters were left commented out:
> 
> #max_mail_processes = 1024
> #auth_process_size = 256
> 
> 
> If anyone has any ideas about where I might be going wrong, 
> please let me 
> know..!
> 
> many thanks
> 
> Jake
> 
> -- 
> Dr Jake Grimmett
> Head Of Scientific Computing
> MRC Laboratory of Molecular Biology
> Hills Road, Cambridge, CB2 0QH, UK.
> Phone 01223 402219
> Mobile 0776 9886539
>