#31692: compilemessages needlessly runs msgfmt on unchanged .po files
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Reporter: cederlys | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Core | Version: master
(Management commands) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I have a project where running `django-admin compilemessages` takes 1.75
seconds. Running it again, when all the `.mo` files already exists and are
up-to-date, also takes 1.75 seconds.
I propose that `compilemessages.py` is changed so that it only invokes
`msgfmt` when it would do anything useful. This can be implemented by
checking the mtime of the `.po` file and the corresponding `.mo` file. (If
statting the `.mo` file fails, treat that as if the mtime was 0.) Only
submit the command to the `executor` if the mtime of the `.po` file is
greater than that of the `.mo` file. In effect: don't do anything if the
`.mo` file is newer than the `.po` file.
There is one issue with this: the way the code currently uses the
`is_writable` function. Since it modifies the mtime of the `.mo` file, you
would have to perform the stat of the `.mo` file before you check if it is
writable. (Or, you could just remove the `is_writable` function and its
use. That feature is, in my opinion, of dubious value, and it doesn't
appear to be documented.)
After I made the changes above, the runtime in the common case where
nothing needs to be done was reduced from 1.75 seconds to 0.2 seconds.
(Unfortunately, I doubt that I will be able to get a Corporate Contributor
License Agreement signed, so I can unfortunately not contribute my
change.)
1.75 seconds may not be much, but when a CI system does it repeatedly, it
adds up.
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Ticket URL: <https://code.djangoproject.com/ticket/31692>
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