"Resource temporarily unavailable", systemd and your FAQ Webpage

[Nicola Nye]

Thanks Stephan!



I will fold your information into the FAQ as this is a topic which comes
up semi regularly on the list.


   Nicola





On Fri, Dec 16, 2016, at 07:54 PM, Stephan Lauffer via Info-cyrus wrote:
> Hello!

> 

> While testing 2.5 we struggled over (known) problems like this...:

> 

>   ...ssh can't fork process to run service imaps/ipv4: Resource 

> temporarily unavailable

> 

> I searchd... and I found your FAQ...

> 

>   https://cyrusimap.org/imap/faqs/o-toomanyprocesses.html

> 

> ...and this "tcp_keepalive = 1" hint was doing a good job, but not 

> fixing our problem completely. Less processes as without this setting
> but too many at all.

> 

> Btw we have a murder with 5 backends and each has about 5k mboxes. 

> With 2.4 we have about 400 imapd processes on the backends (in normal
> state) and about 800 on the proxy. Peaks raises this values for sure.
> 

> But we still wasn't able to get over a limit of about 500 imapds on 

> our new system which is running 2.5. Yesterday night I found our 

> problem:

> 

>   SYSTEMD

> 

> (and not cyrus-imapd-2.5, but 2.5 was running with systemd here...)

> 

> I guess there may be more people out there which may be interested in
> a solition (we will add fixes to our systemd scripts of our suse bulds
> soon, see  

> https://build.opensuse.org/package/show/home:nixda:devel/cyrus-imapd).
> 

> The first problem there is:

> 

> Systemd does not care about your /etc/security/limits.conf

> 

> The second problem is:

> 

> Systemd comes with a new limit called "TasksMax". You will find this
> limit f.e. in /etc/systemd/system.conf as "DefaultTasksMax=512". But
> you will NOT find this limit in "cat /proc/`cat 

> /var/run/cyrus.pid`/limits".

> 

> The solution is to add a file with a systemd override for this 

> service. F.e. use the systemctl edit <sevice> command... (like 

> "systemctl edit cyrus-imapd.service") or place a file in 

> /etc/systemd/system/cyrus-imapd.service.d/override.conf with f.e.:

> 

> [Service]

> TasksMax=2048

> LimitNOFILE=10000

> 

> The LimitNOFILE is just a guess... maybe you may not need this here.

> 

> After setting this override you will see a status information about 

> your process count and limit like this:

> 

>   # systemctl status cyrus-imapd.service

> ● cyrus-imapd.service - The Cyrus IMAP and POP Mail Server

>     Loaded: loaded (/usr/lib/systemd/system/cyrus-imapd.service; 

> enabled; vendor preset: disabled)

>   Drop-In: /etc/systemd/system/cyrus-imapd.service.d

>             └─override.conf

>     Active: active (running) since Thu 2016-12-15 20:51:17 CET;
>     12h ago
>   Main PID: 12901 (master)

>     Tasks: 326 (limit: 2048)

> [...]

> 

> 

> What about adding a short hint to your faq? Yes, it is not a cyrus 

> problem. And yes, a sysadmin should know... but... I guess systemd in
> depth may not be good known as the old ulimit thing and if you are 

> searching in the web 99% of the hits deal with ulimit.

> 

> 

> --

> Liebe Gruesse, with best regards

> Stephan Lauffer

> 

> Pedagogical University Freiburg - Germany

> http://www.ph-freiburg.de/zik/

> Fon/ Fax: +49 761 682 -559/ -486

> ----

> Cyrus Home Page: http://www.cyrusimap.org/

> List Archives/Info: http://lists.andrew.cmu.edu/pipermail/info-cyrus/
> To Unsubscribe:

> https://lists.andrew.cmu.edu/mailman/listinfo/info-cyrus

> Email had 1 attachment:


>  * smime.p7s 8k (application/pkcs7-signature)

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.andrew.cmu.edu/pipermail/info-cyrus/attachments/20161217/55220ec4/attachment.html>