[tsc-devel] On the server issues

Quintus | Mon, 19 Jan 2015 22:50:32 UTC

Hi everyone,

as you might have guessed, I don’t have much time right now. I’ve
skimmed through the IRC logs of the last days and wanted to comment on
it a bit.

The setup currently runs a standard Apache httpd on Debian wheezy. The
forum runs on a Thin server that is reverse-proxied behind the httpd,
and the wiki runs a Python software named Moinmoin via CGI. All the
other pages are simple, static HTML pages that are either written
incrementally (like the chatlogs) or on a regular interval via Cron
(such as the mailinglist archive), or even manually such as the main
page.

The reason for the current outages is the Moinmoin wiki software. From
time to time, it gets cought in an infinite loop with 100% CPU usage,
blocking httpd completely and having heavy impact on the rest of the
server. The problem in the wiki software seems to have been resolved in
newer versions of Moinmoin, but Debian’s policy won’t permit to get a
more recent version into their repositories.

As has been suggested, the problem thus is _not_ memory usage. There’s
plenty of free memory on the server. It’s just the 100% CPU problem
caused by the Python processes and thus it’s not really httpd’s
fault. If we swapped out httpd for nginx, the problem would occur
likewise.

This leaves us with the option to either upgrade to Debian Jessie,
upgrade only Moinmoin to a more recent version and afterwards manually
take care to keep it up-to-date without the package manager, use another
wiki software, or put proper monitoring in place that automatically
restarts faulty daemons. I personally favour the last option, as
monitoring is something that should be good measure for any server. The
same goes for backups. Once I’m done with my exams, I’m going to do some
proper server configuration in this regard. Maybe I can even insert
something in the meanwhile...

A sidenote for anyone having server access: On login, the MOTD is
printed to the terminal. It contains the names and valid email addresses
of all people who have full admin access via sudo. In case you urgently
need an admin email address, that’s where you want to look.

Also, if you didn’t know yet, I offer SSH (and thus SFTP with download
area!) access to anyone involved in the TSC project. Just drop me an
email. If you don’t know where to put your large files to distribute
them, this is for you.

The most reliable way to reach me currently is by email, either directly
(see From header of this email), or by sending to the mailinglist. I’ll
see both, even if I don’t reply immediately.

Valete,
Quintus

-- 
Blog: http://www.quintilianus.eu

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