Issue #22293 has been updated by duerst (Martin Dürst). Just some comments to hopefully help this issue move forward. `unicode_normalize` uses two hashes, `UnicodeNormalize::NF_HASH_C` and `UnicodeNormalize::NF_HASH_D`. These hashes are used to cache results of composition (`NF_HASH_C`) or decomposition (`NF_HASH_D`). They are updated with default procs when a key is not found (i.e. when the result of a normalization operation isn't already in the hash, and therefore has to be calculated.) As long as the default proc isn't triggered, using `unicode_normalize` in parallel in two different ractors (or threads, or fibers, or anything else of that sort) is fine. But when the default proc is executed, the hash can change. If the two key for which the default proc is executed in parallel are the same, then resulting value will also be the same (because Unicode normalization is deterministic). I do not know the implementation of `Hash` in detail. If it can be used in parallel in threads and the like, it should be possible to get `unicode_normalize` to work in all Ractors in parallel. Potentially, just declaring the involved hashes as sharable could be enough. ---------------------------------------- Bug #22293: `String#unicode_normalize` does not work in non-main Ractor https://bugs.ruby-lang.org/issues/22293#change-118810 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Assignee: ko1 (Koichi Sasada) * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- This fails consistently since Ruby 3.0 (except for using `#take` instead of `#value`). ```console $ ruby -v -W:no-ex -e 'p Ractor.new{"aaa".unicode_normalize}.value' ruby 4.1.0dev (2026-09-04T13:17:34Z master 3643154e6d) +PRISM [arm64-darwin25] #<Thread:0x0000000123bf0008 run> terminated with exception (report_on_exception is true): /opt/local/lib/ruby/4.1.0+4/unicode_normalize/normalize.rb:138:in 'UnicodeNormalize.normalize': can not access non-shareable objects in constant UnicodeNormalize::NF_HASH_C by non-main ractor. (Ractor::IsolationError) from -e:1:in 'String#unicode_normalize' from -e:1:in 'block in <main>' -e:1:in 'Ractor#value': thrown by remote Ractor. (Ractor::RemoteError) from -e:1:in '<main>' /opt/local/lib/ruby/4.1.0+4/unicode_normalize/normalize.rb:138:in 'UnicodeNormalize.normalize': can not access non-shareable objects in constant UnicodeNormalize::NF_HASH_C by non-main ractor. (Ractor::IsolationError) from -e:1:in 'String#unicode_normalize' from -e:1:in 'block in <main>' ``` -- https://bugs.ruby-lang.org/