New submission from Hans-Peter Jansen:
In an attempt of using ctypes.from_buffer() to map a structure to a memory
mapped file, it is important to destroy the mapping after use, because the mmap
won't be resizable or freeable correctly until then.
The best approach, I was able to came up with is using a context manager, but
calling the dtor of the mapping in __exit__ is not enough, which results to
code like this:
with StructMap(ctypes_struct, mm, offest) as smap:
smap.xxx = 'blabla'
del smap # necessary, but ugly
Without the del, the "with" variable still exist in the local context, hence
the mapping still exist, until it is explicitly destroyed.
I hope, that ctypes is able to (or can be made to) actively remove the mapping
in the __exit__ part of the context manager.
I've put some code on stackoverflow to play with this:
http://stackoverflow.com/questions/41077696/python-ctypes-from-buffer-mapping-with-context-manager-into-memory-mapped-file
The problem seems to exist with the linux mmap implementation only.
----------
components: ctypes
messages: 283188
nosy: frispete
priority: normal
severity: normal
status: open
title: ctypes.from_buffer counterpart to actively remove the mapping
type: behavior
versions: Python 3.7
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Python tracker <[email protected]>
<http://bugs.python.org/issue28970>
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