From: "byroot (Jean Boussier) via ruby-core" Date: 2024-07-26T09:23:48+00:00 Subject: [ruby-core:118692] [Ruby master Misc#20652] Memory allocation for gsub has increased from Ruby 2.7 to 3.3 Issue #20652 has been updated by byroot (Jean Boussier). > it could be better if we had a gsub variant that doesn't touch $~. Right, but the problem is beyond `gsub`, e.g.: ```ruby >> "abba"[/(bb|[^b]{2})/] => "bb" >> $~ => # ``` So introducing `gsub( backref: false)` or `gsub_no_backref` would solve one case but would leave many others. Hence why I think the only way to handle this general problem without introducing tons of new methods and lots of code churn would be a new Regexp flag. ---------------------------------------- Misc #20652: Memory allocation for gsub has increased from Ruby 2.7 to 3.3 https://bugs.ruby-lang.org/issues/20652#change-109228 * Author: orisano (Nao Yonashiro) * Status: Open * Assignee: jeremyevans0 (Jeremy Evans) ---------------------------------------- I recently upgraded from ruby 2.7.7 to 3.3.1 and noticed that the GC load increased. When I used the allocation profiler to investigate, I found that memory allocation from gsub had increased. The problem was code like this: ```ruby s = "foo " s.gsub(/ (\s+)/) { " #{' ' * Regexp.last_match(1).length}" } ``` When I compared the results of heap-profiler between 2.7.7 and 3.3.1, I found that MatchData was increasing. https://gist.github.com/orisano/98792dee260106e9b6fcb45bbabeb1e6 https://github.com/ruby/ruby/commit/abc0304cb28cb9dcc3476993bc487884c139fd11 I discovered that the cause is this commit, which stopped reusing backref to avoid race conditions. Is there a way to reuse backref while still avoiding race conditions? -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/