[yt-users] yt3.3dev MPI puzzle

Kacper Kowalik xarthisius.kk at gmail.com
Tue Mar 22 09:05:41 PDT 2016


On 03/21/2016 06:07 PM, Stuart Levy wrote:
> Hello yt people,
>
> I'm trying to use MPI on a simple Enzo volume-rendering script, using
> the latest yt33 dev from bitbucket, and am getting a puzzling
> behavior.   (MPI so as to reduce the load time.)
>
> Symptom: the datatype of the Scene.last_render field is inconsistent:
> it's YTImageArray when successful, but just plain YTArray when using MPI
> on the right (wrong) data, and so sc.save() fails.    It's easy to work
> around and save the image another way, but makes me worried that
> something else is wrong, or that I'm misusing yt.
>
> It is somehow data-dependent.   The error doesn't happen when I use the
> tiny enzo dataset in .../yt-hg/tests/DD0010/moving7_0010, nor the
> enzo_tiny_cosmology sample (DD0043).   But it *does* happen when I use a
> somewhat-larger-but-not-huge simulation from John Wise - the
> low-resolution PopIII-star simulation he'd given us last year.   A
> single timestep from it is ~46MB and has only a few dozen grids.
>
> I could post the data somewhere if John Wise would be OK with that - John?
>
> Demo code in:
>      http://paste.yt-project.org/show/6343/
> And its output when run under mpirun:
>      http://paste.yt-project.org/show/6344/
>
> The one change to the yt code from 'tip' (bed01b2c838c) is this diagnostic:
> diff -r bed01b2c838c yt/visualization/volume_rendering/scene.py
> --- a/yt/visualization/volume_rendering/scene.py    Mon Mar 21 14:15:54
> 2016 -0700
> +++ b/yt/visualization/volume_rendering/scene.py    Mon Mar 21 18:01:20
> 2016 -0500
> @@ -284,6 +284,7 @@
>               self.render()
>
>           mylog.info("Saving render %s", fname)
> +    print "about to write_png() - Scene.last_render",
> type(self.last_render), "shape",self.last_render.shape, " => ",
> dir(self.last_render)
>           self.last_render.write_png(fname, sigma_clip=sigma_clip)

Hi Stuart,
I've issued PR 2066 [1] that should fix this.
Cheers,
Kacper

[1] https://bitbucket.org/yt_analysis/yt/pull-requests/2066/



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