[yt-users] only_on_root

Nathan Goldbaum goldbaum at ucolick.org
Tue Nov 22 09:10:32 PST 2011 

I've also has luck importing the global MPI communicator and then doing I/O only on the processor with rank 0:

from mpi4py import MPI

do parallel yt stuff

if MPI.COMM_WORLD.rank == 0:
    do file I/O stuff



On Nov 22, 2011, at 8:56 AM, Britton Smith <brittonsmith at gmail.com> wrote:

> Hi Christine,
> 
> I'm not sure you can use the only_on_root like that.  Someone can correct me if I'm wrong.  However, you can do this:
> 
> @only_on_root
> def do_something:
>       do_stuff
>       more_stuff
>       return stuff
> 
> do_something()
> 
> Britton
> 
> On Tue, Nov 22, 2011 at 11:49 AM, Christine Simpson <csimpson at astro.columbia.edu> wrote:
> Hi,
> 
> I'm trying to run a script with parallel yt that does some non-yt io.
> I'm a little confused about how to use only_on_root.
> 
> Here is a test script I've tried:
> 
> from yt.mods import *
> from yt.visualization.api import PlotCollection
> 
> import matplotlib.colorbar as cb
> 
> path =
> "/scratch/01112/tg803911/halo88_therm_feed_3.7e-6_LW_RadiationShield_lmax12/DD0010/"
> fn = "output_0010"
> pf = load(path+fn)
> pc = PlotCollection(pf)
> pc.add_projection("Density",0)
> pc.set_width(20,'kpc')
> pc.save(fn)
> 
> filename = 'hello_world'
> 
> file = only_on_root(open(filename,'w'))
> only_on_root(file.write("hello_world \n"))
> only_on_root(file.close())
> 
> Pasted below is the error.  I'm uncertain about the syntax of
> only_on_root.  Do I just wrap it around normal commands?  Also, it seems
> that the write command is trying to execute on all the processors.  That
> shouldn't be happening, right?
> 
> P007 yt : [INFO     ] 2011-11-22 09:50:20,558 Saved
> output_0010_Projection_x_Density.png
> P008 yt : [INFO     ] 2011-11-22 09:50:20,558 Saved
> output_0010_Projection_x_Density.png
> P009 yt : [INFO     ] 2011-11-22 09:50:20,560 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>  File "test_parallel_yt.py", line 19, in <module>
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
>    only_on_root(file.write("hello_world \n"))
> AttributeError    : only_on_root(file.write("hello_world \n"))
> 'NoneType' object has no attribute 'write'
> P010 yt : [INFO     ] 2011-11-22 09:50:20,561 Saved
> output_0010_Projection_x_Density.png
> AttributeErrorP011 yt : [INFO     ] 2011-11-22 09:50:20,561 Saved
> output_0010_Projection_x_Density.png
> : 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> Traceback (most recent call last):
> AttributeError:   File "test_parallel_yt.py", line 19, in <module>
> 'NoneType' object has no attribute 'write'
> P005 yt : [INFO     ] 2011-11-22 09:50:20,562 Saved
> output_0010_Projection_x_Density.png
> P004 yt : [INFO     ] 2011-11-22 09:50:20,562 Saved
> output_0010_Projection_x_Density.png
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P002 yt : [INFO     ] 2011-11-22 09:50:20,583 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P001 yt : [INFO     ] 2011-11-22 09:50:20,589 Saved
> output_0010_Projection_x_Density.png
> P003 yt : [INFO     ] 2011-11-22 09:50:20,589 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P013 yt : [INFO     ] 2011-11-22 09:50:20,593 Saved
> output_0010_Projection_x_Density.png
> P014 yt : [INFO     ] 2011-11-22 09:50:20,593 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P012 yt : [INFO     ] 2011-11-22 09:50:20,596 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P015 yt : [INFO     ] 2011-11-22 09:50:20,599 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 19, in <module>
>    only_on_root(file.write("hello_world \n"))
> AttributeError: 'NoneType' object has no attribute 'write'
> P000 yt : [INFO     ] 2011-11-22 09:50:21,410 Saved
> output_0010_Projection_x_Density.png
> Traceback (most recent call last):
>  File "test_parallel_yt.py", line 18, in <module>
>    file = only_on_root(open(filename,'w'))
>  File
> "/share/home/01112/tg803911/yt_17May2011/yt-x86_64/src/yt-hg/yt/funcs.py", line 357, in only_on_root
>    return func(*args, **kwargs)
> TypeError: 'file' object is not callable
> mpispawn.c:303 Unexpected exit status
> 
> Child exited abnormally!
> Killing remote processes...DONE
> 
> 
> 
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