Issue #20462 has been updated by byroot (Jean Boussier). Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: UNKNOWN be1bbd5b7d40ad863ab35097765d3754726bbd54 very explicitly removes the cache. What's unclear is whether it was intended, or if the intent was to reimplement it differently and it was forgotten. @ko1 could you let us know what the intent was? ---------------------------------------- Bug #20462: Native threads are no longer reused https://bugs.ruby-lang.org/issues/20462#change-108846 * Author: tenderlovemaking (Aaron Patterson) * Status: Open * Backport: 3.1: DONTNEED, 3.2: DONTNEED, 3.3: UNKNOWN ---------------------------------------- Ruby used to reuse native threads in order to amortize the cost of making a pthread. For example this program: ```ruby ntids = 1000.times.map { Thread.new { Thread.current.native_thread_id }.value } p ntids.uniq.length ``` With Ruby 3.2.0, this would return 1. With Ruby 3.3.x, it returns 1000. It means we cannot amortize the cost of a pthread for short lived threads. I was able to bisect this to commit be1bbd5b7d40ad863ab35097765d3754726bbd54. But the change is big so I don't know how to fix it. -- https://bugs.ruby-lang.org/