[Simgrid-user] Excessive Memory Use

Wagner Kolberg wkolberg at inf.ufrgs.br
Thu Jul 21 17:00:33 CEST 2011


Hi, I'm working on this same project and I'll try to explain what we are
doing in our code, so we can solve the problem.

That's the THROW_IMPOSSIBLE which leaks. So, you are experiencing a
> part of the code which is not tested, and you're hiding the abort
> message. I guess that you have a try/catch in your code swallowing
> exceptions, in finish_all_task_copies (master.c:573)
>
> This bug report is precious to me, and I'd really appreciate if you
> could give me what's needed to reproduce and investigate myself.
>

Ok, so... to model our system, we create some tasks that are supposed to be
copies/replicas of other tasks. When the first of the replicas finishes, we
must kill the other ones.

The master node has a code like this:

TRY { MSG_task_cancel (task_list[i][tid]); } CATCH (e) {}
MSG_task_destroy (task_list[i][tid]);

And the worker host has something like this:

TRY { MSG_task_execute (task); } CATCH (e) {}

Maybe we are not using the try/catch block correctly? ... Is there any
simgrid function that we can call inside the catch block, to avoid the
memory usage? It doesn't seem to be a leak per se, since the memory is
still reachable according to valgrind.

As for your problem, did I mention that we managed to launch 2M nodes
> by reducing the size of the system stack that each of them gets? Check
> the contexts/stack_size command line configuration option.
>

I have no idea of what you are talking about, but it seems to be very
interesting. We will take a look into that for sure! ;)


> And to finally answer your question, the routing code were changed
> recently (as in "this year", not sure which stable version anymore),
> but it only leaded to much more memory efficient representations.
>

Ok, great. We already simulated large environments with simgrid, but our
current work is different, and we are using some simgrid features for the
first time, and that's why we didn't know what to expect.

Thanks for your time!

Cheers,
Wagner
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