Fix a race condition in TexManager.make_dvi. #30426
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tacaswell
reviewed
Aug 14, 2025
lib/matplotlib/texmanager.py
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| @@ -296,12 +298,12 @@ def make_dvi(cls, tex, fontsize): | |||
| # will be blocked when `openin_any = p` in texmf.cnf). | |||
| cwd = Path(dvifile).parent | |||
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I don't think we need this any more?
tacaswell
approved these changes
Aug 14, 2025
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It's still used by the TemporaryDirectory call. |
timhoffm
reviewed
Aug 14, 2025
lib/matplotlib/texmanager.py
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| # Also generate the tex source in the main cache directory, but | ||
| # only for backcompat. | ||
| cls.make_tex(tex, fontsize) |
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Maybe inline make_tex for clarity
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| # Also generate the tex source in the main cache directory, but | |
| # only for backcompat. | |
| cls.make_tex(tex, fontsize) | |
| tex_source = cls._get_tex_source(tex, fontsize), encoding='utf-8') | |
| # Also generate the .tex file in the main cache directory, but | |
| # only for backcompat. | |
| Path(cls.get_basefile(tex, fontsize) + ".tex").write_text(tex_source) |
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I went for another approach, which is to move the tex file from the temporary directory to the main cache when done with it as well. How does that look to you?
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| Path(tmpdir, "file.tex").write_text( | ||
| cls._get_tex_source(tex, fontsize), encoding='utf-8') |
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And then here just
Suggested change
| Path(tmpdir, "file.tex").write_text( | |
| cls._get_tex_source(tex, fontsize), encoding='utf-8') | |
| Path(tmpdir, "file.tex").write_text(tex_source) |
Previously, a race condition could occur if, while a process had called make_tex (generating the tex file in the global cache) and was going to call the latex subprocess (to generate the dvi file), another process also called make_tex for the same tex string and started rewriting the tex source. In that case, the latex subprocess could see a partially written (invalid) tex source. Fix that by generating the tex source in a process-private temporary directory, where the latex process is already going to run anyways. (This is cheap compared to the latex subprocess invocation.) Apply a similar strategy for make_png as well.
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I chose to also fix make_png here as well. |
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Previously, a race condition could occur if, while a process had called make_tex (generating the tex file in the global cache) and was going to call the latex subprocess (to generate the dvi file), another process also called make_tex for the same tex string and started rewriting the tex source. In that case, the latex subprocess could see a partially written (invalid) tex source.
Fix that by generating the tex source in a process-private temporary directory, where the latex process is already going to run anyways. (This is cheap compared to the latex subprocess invocation.)
See #30420 (comment) (point (2)).
Edit: did the same to make_png.
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