matplotlib not using persistent font cache

[mreppen]

Expected Behavior

Use the default matplotlib font cache location, e.g., ~/.cache/matplotlib or artisan-specific directory like ~/.cache/artisan.

Actual Behavior

Uses temporary location, and thus has to rebuild cache at every run (takes a long time on my system).
In my case, it is written to a subdirectory of /tmp/, which of course is different every time artisan is run.

Specifications

• Artisan Version: 1.3.0
• Platform (Mac/Windows/Linux + OS version): Arch Linux running from .deb file (same on rpm)

Although I'm not using a supported distribution, the fact that the cache is stored in a temporary directory suggests the problem would occur also on other distributions.

[MAKOMO]

Seems to be a platform specific issue. On Mac OS X (build with py2app) the users standard .matplotlib font cache is used or created/updated. Could be an issue on pyinstaller builds (Linux/Windows). Found this one: pyinstaller/pyinstaller#617

[rpaulo]

Looks like it's caused by how pyinstaller implements it:

pyinstaller/pyinstaller@213bfc3

[rpaulo]

Relevant explanation:

# When you run your onefile exe for the first time it's extracted to for example
# "_MEIxxxxx" temp directory and fontList.cache file is created with fonts paths
# pointing to this directory.
#
# Second time you run your exe new directory is created "_MEIyyyyy" but
# fontList.cache file still points to previous directory which was deleted.
# And then you will get error like:
#
#     RuntimeError: Could not open facefile
#
# We need to force matplotlib to recreate config directory every time you run
# your app.

[rpaulo]

@mreppen I suspect that fixing this will create other problems...

[mreppen]

The description of the behavior is not entirely clear to me, likely because I don't really know PyInstaller.

It seems to me like the hook with that comment is responsible for setting up the new temporary mpl directory. Why couldn't it just copy/link the fontList.cache from the default directory?

[rpaulo]

pyinstaller/pyinstaller#3472