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HAProxy - Server Timeout and Client Timeout

Posted by Martel, Michael H. 
Martel, Michael H.
HAProxy - Server Timeout and Client Timeout
June 05, 2018 09:20PM
Greetings!

We're running HAproxy 1.5.18 on RedHat Enterprise 7.4, as the load balancer for our LMS (Moodle). We have found that the course backup feature in Moodle will return a 5xx error on some backups. We have determined that the "timeout server" value needed to be increased.

Initially we were using a "timeout client 1m" and "timeout server 1m" . Adjusting the server to "timeout server 12m" fixes the problem and does not appear to introduce any other issues in our testing.

I can't see any reason that I should have the "timeout client" and the "timeout server" set to the same value.

Is there anything I should watch out for after increasing the "timeout server" by such a large amount ?

Thanks!



Michael

--

--------------------------------o---------------------------------
Michael H. Martel | Director of Data Center Administration
michael.martel@vsc.edu | Systems and Security Administrator
Vermont State Colleges | PH:802-224-3010 FX:802-224-3035
Andrew Smalley
Re: HAProxy - Server Timeout and Client Timeout
June 05, 2018 09:30PM
HI Michael

We often see the client/server timeouts requiring to be raised as you
have found,

A good default value for client/server timeouts are below and I include the
connect timeout too in milliseconds

timeout connect 4000
timeout client 42000
timeout server 43000

Say for example you run a long report on a website, maybe it will take
5 or 10 min's to
complete so you would raise the server timeout to match the required
maximum timeout where possible
allowing for the report to run and the server, not timeout.

I hope this helps


Andruw Smalley

Loadbalancer.org Ltd.

www.loadbalancer.org
+1 888 867 9504 / +44 (0)330 380 1064
asmalley@loadbalancer.org

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On 5 June 2018 at 20:11, Martel, Michael H. <[email protected]> wrote:
> Greetings!
>
> We're running HAproxy 1.5.18 on RedHat Enterprise 7.4, as the load balancer for our LMS (Moodle). We have found that the course backup feature in Moodle will return a 5xx error on some backups. We have determined that the "timeout server" value needed to be increased.
>
> Initially we were using a "timeout client 1m" and "timeout server 1m" . Adjusting the server to "timeout server 12m" fixes the problem and does not appear to introduce any other issues in our testing.
>
> I can't see any reason that I should have the "timeout client" and the "timeout server" set to the same value.
>
> Is there anything I should watch out for after increasing the "timeout server" by such a large amount ?
>
> Thanks!
>
>
>
> Michael
>
> --
>
> --------------------------------o---------------------------------
> Michael H. Martel | Director of Data Center Administration
> michael.martel@vsc.edu | Systems and Security Administrator
> Vermont State Colleges | PH:802-224-3010 FX:802-224-3035
>
>
Jarno Huuskonen
Re: HAProxy - Server Timeout and Client Timeout
June 06, 2018 02:30PM
Hi,

On Tue, Jun 05, Martel, Michael H. wrote:
> We're running HAproxy 1.5.18 on RedHat Enterprise 7.4, as the load balancer for our LMS (Moodle). We have found that the course backup feature in Moodle will return a 5xx error on some backups. We have determined that the "timeout server" value needed to be increased.

Do these backup requests have specific urls that you can match with acl ?

If you use separate backend for moodle backups then it should be
possible to increase timeout server for just the backup requests.

Something like
frontend fe_moodle
acl backup_req path_sub /something/backup
use_backend moodle_backup if backup_req
default_backend moodle
....
backend moodle
timeout server 1m
....

backend moodle_backup
timeout server 12m
server moodle1 ... track moodle/moodle1 ...
server moodle2 ... track moodle/moodle2 ...

> Initially we were using a "timeout client 1m" and "timeout server 1m" . Adjusting the server to "timeout server 12m" fixes the problem and does not appear to introduce any other issues in our testing.
>
> I can't see any reason that I should have the "timeout client" and the "timeout server" set to the same value.
>
> Is there anything I should watch out for after increasing the "timeout server" by such a large amount ?

Probably not, but AFAIK if the backend server "dies" after haproxy has
forwarded the request (and before server responds) then client has to
wait for timeout server (in reality I think everyone will just click
stop or reload instead of waiting for the really long timeout).

-Jarno

--
Jarno Huuskonen
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