[Mono-list] mod-mono-server process busy 100% or 200% CPU

[William Ivanski]

We also ran into this problem here.

I never could really track which was the cause of the CPU overload. BUT...

Our XSP4 process access an Oracle XE database. At the time of the 100% -
200% CPU overload, the Oracle processes were processing some stuff, and the
memory and swap usage of the Oracle processes was high too.

Memory usage of the XSP4 processes was normal.

So, I might guess the Oracle processes "hanged" or found a "deadlock", and
somehow the XSP4 overload the processor when it cannot get immediate
response from the Oracle server.

William Ivanski


2014-09-03 10:03 GMT-03:00 Maxim <makska at yandex.ru>:

> Hello!
>
> I've just created ASP.Net website and ran it on Apache&mono on Linux.
> And I've got strange situation. After 50.000-100.000 requests
> mod-mono-server process unexpectedly become busy with 100% or 200%
> (exactly) CPU load.
> After restarting mono process via mono-ctl panel cpu consumption returns
> to 1-3%.
> I've found some errors like
> [Wed Sep 03 16:02:57 2014] [error] (32)Broken pipe: write_data failed
> [Wed Sep 03 16:02:57 2014] [error] (32)Broken pipe: write_data failed
> [Wed Sep 03 16:02:57 2014] [error] command failed: failed to get client
> block (data)
> in apache error_log, but it seems like there are no relations in time
> between these errors and busy moment.
>
> So, the questions:
> 1) are there any way to know what is happening in this situation? What
> threads are running, etc... I'm not sure the reason is in mono itself, may
> be the reason is in my application. Full profiling on production server is
> not possible, I mean just a few statistics,
> 2) if the reason is in garbage collector: are there any ways to tune it?
> Or to switch from sgen to old Boehm or so on?
>
> Any help are highly appreciated!
>
> P.S. Mono 3.2.8 compiled from sources on standard CentOS 6.5
> # mono -V
> Mono JIT compiler version 3.2.8 (tarball Wed Jun 11 00:48:42 MSK 2014)
> Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors.
> www.mono-project.com
>     TLS:           __thread
>     SIGSEGV:       altstack
>     Notifications: epoll
>     Architecture:  amd64
>     Disabled:      none
>     Misc:          softdebug
>     LLVM:          supported, not enabled.
>     GC:            sgen
>
> # httpd -v
> Server version: Apache/2.2.15 (Unix)
> Server built:   Apr  3 2014 23:56:16
>
> # uname -a
> Linux web1.server 2.6.32-431.17.1.el6.x86_64 #1 SMP Wed May 7 23:32:49 UTC
> 2014 x86_64 x86_64 x86_64 GNU/Linux
>
>
> With best wishes,
> Max Karavaev
> _______________________________________________
> Mono-list maillist  -  Mono-list at lists.ximian.com
> http://lists.ximian.com/mailman/listinfo/mono-list
>
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