From: "NeilW (Neil Wilson) via ruby-core" Date: 2025-02-26T16:21:42+00:00 Subject: [ruby-core:121182] [Ruby master Bug#21158] Ractor using 'receive_if' sits in busy wait when there are skipped messages in the incoming queue Issue #21158 has been reported by NeilW (Neil Wilson). ---------------------------------------- Bug #21158: Ractor using 'receive_if' sits in busy wait when there are skipped messages in the incoming queue https://bugs.ruby-lang.org/issues/21158 * Author: NeilW (Neil Wilson) * Status: Open * ruby -v: ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When using the conditional receive example from the Ractor documentation (either as a script, or within irb) 
r = Ractor.new do
  val = Ractor.receive_if{|msg| msg.is_a?(Array)}
  puts "Received successfully: #{val}"
end

r.send(1)
r.send('test')
ruby will sit in busy wait, pegging the processor at 100%, until it gets a message that matches the condition. Within irb it will often stop the REPL responding. The same problem occurs on ruby 3.02, 3.3.7 and 3.4.1 -- 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/