Distribution.from_shape is producing localarrays with size 0

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
distributed-systems

Research direction

Reproduce the four-engine example using Distribution.from_shape and localshapes, then inspect distarray/metadata_utils.py at line 143 and the surrounding grid-shape calculation. Determine how the communicator size affects an axis that is not evenly divisible, and consider the issue done when the same distribution no longer produces a zero-sized localarray.

Written by the indexing model from the issue text.

Description

bug

With 4 engines:

In [1]: from distarray.dist import Context, Distribution

In [2]: context = Context()

In [3]: distribution = Distribution.from_shape(context, (9, 8), dist=('b', 'n')) 

In [4]: distribution.localshapes()
Out[4]: [(3, 8), (3, 8), (3, 8), (0, 8)]

This appears to be from this line.

The size of this axis of the grid_shape is set to comm_size, which doesn't divide into the size of the corresponding axis of the DistArray.

Dominant language
Python
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5
Forks
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