Issue 32379: MRO computation could be faster (original) (raw)

This issue has been migrated to GitHub: https://github.com/python/cpython/issues/76560

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Created on 2017-12-19 19:54 by pitrou, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (5)
msg308674 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2017-12-19 19:54
MRO computation involves a complicated merge calculation over several lists. But, for the simple (common) case where a class has a single base, the computation could be much simpler: take the base's MRO and prepend the derived class.
msg308675 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2017-12-19 20:00
Benchmarks: * before: $ ./env-orig/bin/pyperf timeit "class Test: pass" ..................... Mean +- std dev: 9.51 us +- 0.17 us * after: $ ./env/bin/pyperf timeit "class Test: pass" ..................... Mean +- std dev: 8.89 us +- 0.09 us
msg308733 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2017-12-20 14:06
LGTM in general. But mro() returns a list. "class Test: pass" is a trivial case. What are results if the class has a parent?
msg308734 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2017-12-20 14:15
Benchmarks with a parent: * Before: $ ./env-orig/bin/pyperf timeit -s "from unittest import TestCase" "class Test(TestCase): pass" ..................... Mean +- std dev: 10.4 us +- 0.1 us * After: $ ./env/bin/pyperf timeit -s "from unittest import TestCase" "class Test(TestCase): pass" ..................... Mean +- std dev: 9.89 us +- 0.12 us
msg308737 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2017-12-20 14:58
New changeset 1f1a34c3145781628e10534440017b3b43211a60 by Antoine Pitrou in branch 'master': bpo-32379: Faster MRO computation for single inheritance (#4932) https://github.com/python/cpython/commit/1f1a34c3145781628e10534440017b3b43211a60