Issue #20104 has been updated by naruse (Yui NARUSE).
Backport changed from 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: REQUIRED to 3.0:
DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONE
ruby_3_3 f585171a6b1d6c20b3c162fd59dc874510ed2a49 merged revision(s)
e12d4c654e3cb7a4473014610bc3bae41aaf811e.
----------------------------------------
Bug #20104: Regexp#match returns nil but allocates T_MATCH objects
https://bugs.ruby-lang.org/issues/20104#change-106547
* Author: jeremyevans0 (Jeremy Evans)
* Status: Closed
* Priority: Normal
* ruby -v: ruby 3.4.0dev (2023-12-30T03:14:38Z master 8e32c01742) [x86_64-openbsd7.4]
* Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONE
----------------------------------------
Between Ruby 3.2 and 3.3, behavior changed so that Regexp#match will allocate a T_MATCH
object even when there is no match. Example code:
```ruby
h = {}
GC.start
GC.disable
ObjectSpace.count_objects(h)
matches = h[:T_MATCH] || 0
md = /\A[A-Z]+\Z/.match('1')
ObjectSpace.count_objects(h)
new_matches = h[:T_MATCH] || 0
puts "/\\A[A-Z]+\\Z/.match('1') => #{md.inspect} generates #{new_matches -
matches} T_MATCH objects"
```
Result with Ruby 1.9-3.2:
```
/\A[A-Z]+\Z/.match('1') => nil generates 0 T_MATCH objects
```
Results with Ruby 3.3.0 and current master branch:
```
/\A[A-Z]+\Z/.match('1') => nil generates 1 T_MATCH objects
```
This results in a measurable performance decrease for both Sinatra and Roda web
applications, as reported at:
https://old.reddit.com/r/ruby/comments/18sxtv9/ruby_330_performance_ups_and…
Thanks to GitHub users kiskoza and tagliala for producing a minimal example showing this
issue:
https://github.com/caxlsx/caxlsx/issues/336
--
https://bugs.ruby-lang.org/