Uh oh!
There was an error while loading. Please reload this page.
bpo-38328: Speed up the creation time of constant list literals. - #16498
Closed
brandtbucher wants to merge 7 commits into
Closed
bpo-38328: Speed up the creation time of constant list literals.#16498brandtbucher wants to merge 7 commits into
brandtbucher wants to merge 7 commits into
Conversation
| samples = [[], [1,2,3], ['1', '2', '3']] | ||
| for sample in samples: | ||
| check(sample, vsize('Pn') + len(sample)*self.P) | ||
| check(list(sample), vsize('Pn') + len(sample)*self.P) |
MemberAuthor
There was a problem hiding this comment.
This is a sys.getsizeof test. The 3-element lists are overallocated, so we resize them here.
brandtbucherforce-pushed
the
constant-lists
branch
from
September 30, 2019 17:02
c41475a to
d53e48dComparebrandtbucher
commented
Oct 4, 2019
MemberAuthor
@serhiy-storchaka Since you proposed something similar a while back, do you mind taking a look at this when you have the chance? |
| h, i+1, consts, j); | ||
| h, i+1-islist, consts, j); | ||
| if (h >= 0 && islist) { | ||
| h = copy_op_arg(codestr, i, BUILD_LIST_UNPACK, 1, i+1); |
There was a problem hiding this comment.
h is not used. Remove h = .
It can also be replaced with
codestr[i] =PACKOPARG(BUILD_LIST_UNPACK, 1);brandtbucher
commented
Oct 5, 2019
MemberAuthor
Thanks for the feedback @serhiy-storchaka. Tests are passing, ready for another review. |
serhiy-storchaka
approved these changes
Oct 5, 2019
brandtbucher
commented
Oct 6, 2019
MemberAuthor
Thank @serhiy-storchaka. Is anything else needed here? |
brandtbucherforce-pushed
the
constant-lists
branch
from
October 14, 2019 19:04
d0f4746 to
091e9cdCompareserhiy-storchaka
commented
Oct 21, 2019
Member
Nothing particular. I just want to fix the issue with list overallocation first. Your PR is good, thank you. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment
5 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This PR contains a small change to the peephole optimizer that converts sequences of:
LOAD_CONST(a),LOAD_CONST(b), ...,BUILD_LIST(n)to
LOAD_CONST((a, b, ...)),BUILD_LIST_UNPACK(1)The improvement quickly becomes significant for lists larger than a few items:
This can be tested on any version of Python by comparing the performance of
[0, 1, 2, ...]vs[*(0, 1, 2, ...)]. The common cases of empty and single-element lists are not affected by this change.This is related to bpo-33325, but that was an invasive change for all collection literals that had an unknown affect on performance. I've limited this one to lists and kept it to a few lines in the peephole optimizer.
https://bugs.python.org/issue38328