8000 Speed up caching of subtype checks by JukkaL · Pull Request #12539 · python/mypy · GitHub
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Speed up caching of subtype checks #12539

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Merged
merged 3 commits into from
Apr 7, 2022
Merged

Speed up caching of subtype checks #12539

merged 3 commits into from
Apr 7, 2022

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JukkaL
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@JukkaL JukkaL commented Apr 7, 2022 •
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This is very performance critical. Implement a few micro-optimizations
to speed caching a bit. In particular, we use dict.get to reduce the
number of dict lookups required, and avoid tuple concatenation which
tends to be a bit slow, as it has to construct temporary objects.

It would probably be even better to avoid using tuples as keys
altogether. This could be a reasonable follow-up improvement.

Avoid caching if last known value is set, since it reduces the
likelihood of cache hits a lot, because the space of literal values
is big (essentially infinite).

Also make the global strict_optional attribute an instance-level
attribute for faster access, as we might now use it more frequently.

I extracted the cached subtype check code into a microbenchmark
and the new implementation seems about twice as fast (in an
artificial setting, though).

Work on #12526 (but should generally make things a little better).

JukkaL added 3 commits April 7, 2022 13:37
@JukkaL
Speed up caching of subtype checks
f05e06c 
This is very performance critical. Implement a few micro-optimizations
to speed caching a bit. In particular, we use dict.get to reduce the
number of dict lookups required, and avoid tuple concatenation which
tends to be a bit slow, as it has to construct temporary objects.

It would probably be even better to avoid using tuples as keys
altogether. This could be a reasonable follow-up improvement.
@JukkaL
Move strict optional state to an instance attribute for faster access
8485279
@JukkaL
Skip caching if last_known_value is set
1a5e890
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github-actions bot commented Apr 7, 2022

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

JukkaL added a commit that referenced this pull request Apr 7, 2022
@JukkaL
Further speed up union simplification
7246dbc 
This tweaks a change made in #12539 that may have slowed things
down. The behavior introduced in the PR was more correct, but it's not
worth a potential major performance regression, since union
simplification is not something we have to get always right for
correctness.

Work on #12526.
@JukkaL JukkaL mentioned this pull request Apr 7, 2022
Merged
@JukkaL JukkaL merged commit cddd819 into master Apr 7, 2022
@JukkaL JukkaL deleted the faster-cached-subtype-check2 branch April 7, 2022 17:55
JukkaL added a commit that referenced this pull request Apr 7, 2022
@JukkaL
Further speed up union simplification (#12541)
ab6185e 
This tweaks a change made in #12539 that may have slowed things
down. The behavior introduced in the PR was more correct, but it's not
worth a potential major performance regression, since union
simplification is not something we have to get always right for
correctness.

Work on #12526.
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@jhance jhance jhance approved these changes

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