[Python] MemoryPool bytes_allocated causes seg

[asfimport]

Python 3.6.5 |Anaconda, Inc.| (default, Mar 29 2018, 18:21:58)
[GCC 7.2.0] on linux
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import pyarrow as pa

mp = pa.MemoryPool()
arr = pa.array([1,2,3], memory_pool=mp)
mp.bytes_allocated()

Segmentation fault (core dumped)

I'll dig into this further, but should bytes_alloacted be returning anything when called like this? Or should it raise NotImplemented?

Reporter: Alex Hagerman / @n0mn0m
Assignee: Wes McKinney / @wesm

PRs and other links:

• GitHub Pull Request #2228

_{Note: This issue was originally created as ARROW-2601. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Uh... Calling the MemoryPool constructor creates an invalid MemoryPool object. It's surprising that pa.array accepts it silently and doesn't crash.

I suppose MemoryPool.bytes_allocated() should check for the pointer being null and raise ValueError in that case. This is already done in other places (see e.g. Tensor._validate()).

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 2228
#2228