Reduce allocations when parsing lockfile #6976
Conversation
| @@ -149,11 +160,11 @@ def parse_dependency(line) | |||
| return unless line =~ NAME_VERSION | |||
| spaces = $1 | |||
| return unless spaces.size == 2 | |||
| name = $2 | |||
| name = -$2 | |||
There was a problem hiding this comment.
Cute. I'm surprised this isn't used more often, enough that it's common practice. First I've seen it and had to look it up.
There was a problem hiding this comment.
I don't think I've seen this before, but I failed when I tried to look it up. What is it?
There was a problem hiding this comment.
Unary minus on String. It freezes the string returns a frozen version of the string. Unary + thaws.
There was a problem hiding this comment.
Huh, how about that. I guess I should have checked the API docs! I did finally find a writeup: https://metaredux.com/posts/2019/05/10/weird-ruby-positive-and-negative-strings.html
There was a problem hiding this comment.
@- is an alias for #dedup, which not only returns a frozen string, but will deduplicate it, leading to reduced retained memory usage
There was a problem hiding this comment.
FYI: The unary operator is -@.
``` ==> memprof.after.txt <== Total allocated: 673.08 kB (7644 objects) Total retained: 107.35 kB (1018 objects) ==> memprof.before.txt <== Total allocated: 739.12 kB (9140 objects) Total retained: 138.61 kB (1695 objects) ``` Savings will scale by the number of lines in the lockfile
segiddins
force-pushed
the
segiddins/reduce-allocations-when-parsing-lockfile
branch
from
8c829df
to
f6abf44
Compare
segiddins
deleted the
segiddins/reduce-allocations-when-parsing-lockfile
branch
…hen-parsing-lockfile Reduce allocations when parsing lockfile (cherry picked from commit 6a2fa57)
…hen-parsing-lockfile Reduce allocations when parsing lockfile (cherry picked from commit 6a2fa57)
…hen-parsing-lockfile Reduce allocations when parsing lockfile (cherry picked from commit 6a2fa57)
…hen-parsing-lockfile Reduce allocations when parsing lockfile (cherry picked from commit 6a2fa57)
Savings will scale by the number of lines in the lockfile
What was the end-user or developer problem that led to this PR?
What is your fix for the problem, implemented in this PR?
Make sure the following tasks are checked