[Opensim-users] Ubuntu and magic mini-trampolines (crash problem)

[Mic Bowman]

in general we see crashes, not freezes. the apparent freeze is usually
caused by the gdb process that gets started when the crash occurs
(kill the gdb process and the simulator crashes "gracefully").

given that the problem seems to happen when log4net attempts to get a
logger associated with a particular script class, my guess is that one
of a couple problems is happening... 1) mono is somehow messing up the
class that is passed in (there are nulls in the argument stack that
look suspicious), 2) log4net isn't as thread-safe as it claims (though
the routine that creates the wrapper object looks fine at first
glance), 3) somehow mono is screwing up the assembly binding when
log4net creates the wrapper. I've looked at the mono code that is
throwing the exception... but it wasn't very helpful without a LOT
more investigation.

at this point, i'm building a custom log4net dll with some additional
debugging in it. which, given that this certainly appears to be a
timing issue, will almost certainly hide the problem. :-(

--mic


On Tue, Apr 28, 2009 at 5:04 AM, Dr Scofield <DrScofield at xyzzyxyzzy.net> wrote:
> Mic Bowman wrote:
>> we've seen the problem with mono_threads_per_cpu set across a range of
>> values (i think we've tried a number of values from 100 to 1000).
>> there doesn't appear to be any correlation.
>
> ok. we had freezes that got cured by increasing MONO_THREADS_PER_CPU, hence my
> asking...
>
> a real deadlock is nasty... :-( sigh.
>
>        DrS/dirk
>>
>> --mic
>>
>>
>> On Mon, Apr 27, 2009 at 10:38 PM, dr scofield <drscofield at xyzzyxyzzy.net> wrote:
>>> Justin Clark-Casey wrote:
>>>
>>> Mic Bowman wrote:
>>>
>>>
>>> I have the same freeze at times. In my case there's a gdb process
>>> running that I can kill off to terminate the simulator.
>>>
>>>
>>>
>>> I presume there's no revealing deadlock information in the thread dump
>>> (perhaps that's too much to hope for :) ?
>>>
>>>
>>> what is your value of the MONO_THREADS_PER_CPU environment variable?
>>>
>>> --
>>> dr dirk husemann ---- math & computer science ---- ibm zurich research lab
>>> RL: hud at zurich.ibm.com - +41 44 724 8573 - http://www.zurich.ibm.com/~hud/
>>> SL: drscofield at xyzzyxyzzy.net --------------------- http://xyzzyxyzzy.net/
>>>
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>>>
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>
>
> --
> dr dirk husemann ---- virtual worlds research ---- ibm zurich research lab
> SL: dr scofield ---- drscofield at xyzzyxyzzy.net ---- http://xyzzyxyzzy.net/
> RL: hud at zurich.ibm.com - +41 44 724 8573 - http://www.zurich.ibm.com/~hud/
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