[Mono-list] mod_mono stability problems

[Marek Habersack]

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On Thu, 15 May 2008 12:23:32 +0200
Oscar van Tol <oscar at usefulbits.nl> wrote:

> Hello,
Hello,

> 
> For the past two months we've been hosting a webservice application on  
> apache2 and mod_mono.
> Since this week we have some real traffic, and stability issues  
> started. We now have about 30.000 requests a day, these make the mono  
> process grow in memory usage to about 2gigs. and the response becomes  
> really bad.
You might want to increase the thread pool size by setting the MONO_THREADS_PER_CPU
environment variable to a value higher than the default 5 (the formula for
calculating the number of threads in the pool is 20 + ($MONO_THREADS_PER_CPU *
number_of_cpus)

> The memory problem is probably cause by the none compacting garbage  
> collector, I solved the performance issue by doing an autorestart  
> every 400 requests. This works great for a while but after a few auto- 
That sounds quite often - I think 1000 would be quite enough in your case.

> restarts it lookes live apache failes to spawn a new mod-mono-server.
> Apache respondes with a 503, when I kill the (old still running)  mono  
> process and restart apache it's back.
> 
> Suggestions?
It's hard to determine what it is just from the description - it might be a
deadlock, might be a memory issue with shared memory. Please compile mod_mono with
- --enable-debug and post apache logs when the 503 happens - that should make it
easier to diagnose what's going on.

best regards,

marek
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