From: "Martin J. Dürst via ruby-core" <ruby-core@...>
Date: 2024-01-22T14:02:02+09:00
Subject: [ruby-core:116361] Re: [Ruby master Bug#20150] Memory leak in grapheme clusters

Hello Tomoyuki,

Many thanks for your careful explanation!

Regards,   Martin.

On 2024-01-19 17:14, nagachika (Tomoyuki Chikanaga) via ruby-core wrote:
> Issue #20150 has been updated by nagachika (Tomoyuki Chikanaga).
> 
> 
> Hello, Martin-sensei.
> 
> In my understandings, there's no explicit rule regarding the order of backporting to each stable branch.
> In this case, I backported the changeset to the 3.2 branch ahead of the 3.3 branch because I hoped to include some obvious bug-fixes in ruby-3.2.3 released yesterday. I also think these fixes should be backported to 3.3 branch before release of ruby-3.3.1, but it's up to naruse-san, the current 3.3 branch maintainer.
> 
> Best Regards,
> 
> ----------------------------------------
> Bug #20150: Memory leak in grapheme clusters
> https://bugs.ruby-lang.org/issues/20150#change-106342
> 
> * Author: peterzhu2118 (Peter Zhu)
> * Status: Closed
> * Priority: Normal
> * Backport: 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: DONE, 3.3: REQUIRED
> ----------------------------------------
> GitHub PR: https://github.com/ruby/ruby/pull/9414
> 
> String#grapheme_cluters and String#each_grapheme_cluster leaks memory because if the string is not UTF-8, then the created regex will not be freed.
> 
> For example:
> 
> ```ruby
> str = "hello world".encode(Encoding::UTF_32LE)
> 
> 10.times do
>    1_000.times do
>      str.grapheme_clusters
>    end
> 
>    puts `ps -o rss= -p #{$$}`
> end
> ```
> 
> Before:
> 
> ```
> 26000
> 42256
> 59008
> 75792
> 92528
> 109232
> 125936
> 142672
> 159392
> 176160
> ```
> 
> After:
> 
> ```
> 9264
> 9504
> 9808
> 10000
> 10128
> 10224
> 10352
> 10544
> 10704
> 10896
> ```
> 
> 
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