[Mono-list] Stablity and usability

Robert Jordan robertj at gmx.net
Wed Jan 30 15:23:33 EST 2008

Hi Maxim,

Maxim Karavaev wrote:
> The second we've found that some of the stability problems depends on
> MySQL data provider (taken from mysql.org website), may be reason of
> it is the problem described here:
> http://www.mono-project.com/ThreadPool_DeadLocks. We switch our
> applications (CMS) to older version of MySQL data provider and its
> become much more stable. Also we've added "MONO_THREADS_PER_CPU=2000"
> to all mono vhosts in apache, it increased stability too.

To which MySQL provider version have you downgrade?

> But one problem with stability still persist. One of the hosted
> web-applications randomly become hang (usually most loaded
> application) and GDB automatically starts for it. Due to it all other
> web-sites in several minutes become "Service temporary unavailable"
> too. This situation happens without any messages in apache, system
> and application logs!! This problem is very hard to reproduce and we

If there were some log output the problem won't be a problem anymore,
isn't it? ;-)

> still can't understand reason. May be reason is in the code of our
> CMS. I've repeated situation similar to that on developer machine,
> but the only I can get is short message "EXCEPTION handling:
> IOException" when I run mod-mono-server2 with "--trace=" option. We
> can try to get dump from GDB if it helps to recognize reason of
> problem.

Please try to get a proper GDB backtrace. See


You should attach GDB as root to the mono process of mod-mono-server.

Additionally, you may want to give mod_mono & XSP from SVN a try.
The latest version is able to limit the rate of parallel requests
made to mod-mono-server. This helps keeping your web server healthy
and there are chances that it's also fixing the problems you've


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