OOM in Dovecot 2.2.13 imap

Bernhard Schmidt berni at birkenwald.de
Mon Jun 23 19:06:37 UTC 2014

On 23.06.2014 16:38, Steffen Kaiser wrote:

> On Mon, 23 Jun 2014, Bernhard Schmidt wrote:
>> we run Dovecot 2.2.13 on Debian Wheezy with a couple thousand mailboxes.
>> We have two users that repeatedly trigger an OOM condition with IMAP.
> Do those users have mailboxes extra ordinary large or is one message of
> them extra ordinary large?

No, not particularly. 8000 Mails (2GB total), the largest mail is 20MB.
> Jun 23 12:53:21 lxmhs74 dovecot: imap(USER): Fatal:
> pool_system_realloc(268435456): Out of memory
> this number likely mean 256MB, is one of your memory limits that large?
> You can see all limits with dovecot -a (note the "-a" instead of "-n").
> Memory limits are vsz_limit, IMHO.

No memory limits outside of dovecot. In dovecot there are the default 

default_vsz_limit = 256 M
service imap {
   vsz_limit = 18446744073709551615 B

Since the largest IMAP processes I can observe are at around 70MB VIRT 
(43MB RSS) I suspect vsz_limit is doing what it is supposed to do (limit 
memory consumption of a run-away process) and something went wrong in 
that mailbox. Thus the backtrace, hoping for someone to confirm.


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