[ruby-core:119169] [Ruby master Bug#20723] `IO#close` is broken on Ruby 3.3+ when using the Fiber scheduler.

13 Sep 2024

      Issue #20723 has been updated by kjtsanaktsidis (KJ Tsanaktsidis).

Sorry about this. I think https://github.com/ruby/ruby/pull/11614 is the smallest diff that will fix the issue (and this should probably be backported to 3.3).

Separately to that, I wonder if we need to wrap up some common function for "wake up this fiber, either with the fiber scheduler or with the thread directly". We've implemented this logic in a number of places... but let's keep that refactor out of the fix PR (since it shouldn't be backported).

----------------------------------------
Bug #20723: `IO#close` is broken on Ruby 3.3+ when using the Fiber scheduler.
https://bugs.ruby-lang.org/issues/20723#change-109747

* Author: ioquatix (Samuel Williams)
* Status: Open
* Assignee: kjtsanaktsidis (KJ Tsanaktsidis)
* Backport: 3.3: REQUIRED
----------------------------------------
The following program seems to work okay on Ruby 3.2 but hangs on Ruby 3.3:

```ruby
#!/usr/bin/env ruby

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'async'
end

require 'socket'

def close_while_reading(io)
  thread = Thread.new do
    Thread.current.report_on_exception = false
    io.wait_readable
  end

  # Wait until the thread is blocked on read:
  Thread.pass until thread.status == "sleep"

  Async do
    io.close
  end

  thread.join
end

begin
  client, server = Socket.pair(:UNIX, :STREAM)
  close_while_reading(client)
rescue => error
  $stderr.puts error.full_message
end
```

-- 
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