Different PDF output between runs with hash randomization enabled about svglib HOT 6 CLOSED

Forgot to post the image.svg file to help reproduce the issue:
image.zip

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I'm on vacation this week and can't test well. But I do remember vaguely having seen some kind of creation timestamps added by reportlab to the PDFs inside the info dict sessions. Svglib doesn't do anything special here and I would maybe suggest raising an issue on the reportlab repo on bitbucket.org.

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@deeplook thanks for the answer.

But I do remember vaguely having seen some kind of creation timestamps added by reportlab to the PDFs inside the info dict sessions.

That makes sense, but I notice that we don't have the same problem when generating PDF with static images (png, jpg), tables or formatted text, only when we have a SVG file.

I will dig around the code to see if I encounter the reason for it.

Thanks again for your answer, and I hope you enjoy your vacation! 👍 🍺

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We have made some improvements in reproducibility of the reportlab code. We now try to support the SOURCE_DATE_EPOCH environment variable; there is also the rl_config.invariant flag which may be used to make certain bits of reportlab more reproducible. However, as you discovered the random hashing introduced recently means that dictionary order is no longer constant.

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@replabrobin thanks for info.

However, as you discovered the random hashing introduced recently means that dictionary order is no longer constant.

Indeed, but now that dicts in Python 3.6 are ordered, this might no longer be an issue in that Python version. I will check this and report back with what I find.

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Hi,

Indeed with Python 3.6 the problem goes away: svglib now always generates the same image files in separate executions (albeit different from files generated in Python 2.7). This indicates that the suspicion about the problem being the random order of dicts in Python>3,<3.6 is correct.

For my purposes it is sufficient to use Python 3.6 and upwards now that Python dicts will always preserve order, so this can be closed from my POV.

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