[New-bugs-announce] [issue42080] Disutils on windows debug build fails without -j1

[John Ehresman]

New submission from John Ehresman <jpe at wingware.com>:

Compiling pillow for a debug build fails without -j1 because distutils parallelizes the build, but there are problems with locking the .pdb file during when compiling the C files.  An example of the error message from a cl.exe command is:

fatal error C1041: cannot open program database 'C:\src\tmp\pillow-test\Pillow-7.2.0\vc140.pdb'; if multiple CL.EXE write to the same .PDB file, please use /FS

Building works with setup.py build_ext --disable-jpeg --disable-tiff --disable-zlib --debug build -j1

My guess is the fix is not to parallelize by default in a debug build; a /FS arg to cl.exe could be used, but that doesn't seem to be recommended.

I realize this might be considered a pillow bug, but my guess is that it affects other packages as well

----------
components: Distutils, Windows
messages: 378959
nosy: dstufft, eric.araujo, jpe, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Disutils on windows debug build fails without -j1
type: compile error
versions: Python 3.8, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42080>
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