Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

gh-91404: Improve re performance #91495

Merged
merged 10 commits into from
Apr 15, 2022
Merged

gh-91404: Improve re performance #91495

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
10 commits
Select commit Hold shift + click to select a range
89e4e5e
Try out computed gotos in the regex engine
brandtbucher Apr 12, 2022
bc378d8
Reduce indirection
brandtbucher Apr 12, 2022
fa98784
More of that
brandtbucher Apr 12, 2022
48a7f1c
Rearrange some stuff
brandtbucher Apr 12, 2022
6f8a9a0
Whitespace
brandtbucher Apr 12, 2022
03d3194
Generate sre_targets.h
brandtbucher Apr 12, 2022
24fa5a1
Catch up with main
brandtbucher Apr 13, 2022
0d30328
blurb add
brandtbucher Apr 13, 2022
fdcde9f
fixup
brandtbucher Apr 13, 2022
d38743f
What's New
brandtbucher Apr 14, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions Doc/whatsnew/3.11.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -512,6 +512,12 @@ Optimizations
becomes 272 bytes from 352 bytes on 64bit platform.
(Contributed by Inada Naoki in :issue:`46845`.)

* :mod:`re`'s regular expression matching engine has been partially refactored,
and now uses computed gotos (or "threaded code") on supported platforms. As a
result, Python 3.11 executes the `pyperformance regular expression benchmarks
<https://pyperformance.readthedocs.io/benchmarks.html#regex-dna>`_ up to 10%
faster than Python 3.10.


Faster CPython
==============
Expand Down
7 changes: 4 additions & 3 deletions Makefile.pre.in
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1351,11 +1351,12 @@ regen-stdlib-module-names: build_all Programs/_testembed
$(UPDATE_FILE) $(srcdir)/Python/stdlib_module_names.h $(srcdir)/Python/stdlib_module_names.h.new

regen-sre:
# Regenerate Modules/_sre/sre_constants.h from Lib/re/_constants.py
# using Tools/scripts/generate_sre_constants.py
# Regenerate Modules/_sre/sre_constants.h and Modules/_sre/sre_targets.h
# from Lib/re/_constants.py using Tools/scripts/generate_sre_constants.py
$(PYTHON_FOR_REGEN) $(srcdir)/Tools/scripts/generate_sre_constants.py \
$(srcdir)/Lib/re/_constants.py \
$(srcdir)/Modules/_sre/sre_constants.h
$(srcdir)/Modules/_sre/sre_constants.h \
$(srcdir)/Modules/_sre/sre_targets.h

Python/compile.o Python/symtable.o Python/ast_unparse.o Python/ast.o Python/future.o: $(srcdir)/Include/internal/pycore_ast.h

Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2022-04-12-19-08-13.gh-issue-91404.zjqYHo.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Improve the performance of :mod:`re` matching by using computed gotos (or
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Add that it speeds up matching by 10-20%.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Please don't. These claimed speedups are highly misleading.

The release notes for 3.9 and 3.10 have various claimed large speedups, yet 3.9 is no faster than 3.8 and 3.10 only a little bit faster.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The benchmark results are convincing to me.

Without this it is not clear why bother with making this change at all.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You'll only see a 10-20% speedup for these specific benchmarks, which are contrived.
Real programs, even those that spend a lot regexes will spend a much lower proportion of their time in the regex library.

Any number we give will be misleading.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This branch vs 3.10:

- regex_v8: 147 ms +- 12 ms -> 132 ms +- 11 ms: 1.11x faster
- regex_effbot: 19.1 ms +- 1.2 ms -> 17.5 ms +- 0.9 ms: 1.10x faster
- regex_dna: 1.30 sec +- 0.01 sec -> 1.24 sec +- 0.01 sec: 1.04x faster

(Those numbers are very close to what you get by combining the latest re perf regressions with the numbers from this PR.)

I'll just leave the NEWS entry as-is (very few people read it anyways). I don't have a strong opinion on what should go in What's New (but @pablogsal might).

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Perhaps the wording "up to 10% faster on the pyperformance regular expression benchmarks" (or similar) might suffice.

Copy link
Member

@pablogsal pablogsal Apr 14, 2022 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think this should indeed go in the What's new. Could you add a small sentence in the Performance section, maybe? Specifying that the improvement is in the re engine and that it only affects re operations? If we need to remove it later is easier than the risk of forgetting to add something.

"threaded code") on supported platforms and removing expensive pointer
indirections.
Loading