multiprocessing issue on windows about bowler HOT 4 CLOSED

Hmm, this raises another barrier to running on Windows. Currently, Bowler will generate inline fixer classes to run the appropriate selectors, filters, and modifiers, due to the way that lib2to3 works. This is fine when using forked processes, because the child processes have the same set of locally generated classes and functions. But Windows can only use spawned processes, requiring all classes and functions to be defined globally so that they are available in the children.

We should instead have Bowler use a single class defined at the global scope, and build some other mechanisms for loading those fixers into the lib2to3 refactoring tool.

from bowler.

@jreese would it make sense to default to in_process=True on Windows for now?

from bowler.

That seems like a reasonable decision until we can find a better alternative.

from bowler.

FYI I had the same AttributeError: Can't pickle local object 'Query.create_fixer.<locals>.Fixer' error on Mac OS X with Python 3.8.1.
Query.execute(in_process=True) helped for now :)

EDIT: just found out this is already known: #111 (comment)

from bowler.