[ruby-core:122488] [Ruby Bug#21158] Ractor using 'receive_if' sits in busy wait when there are skipped messages in the incoming queue
From:
"jhawthorn (John Hawthorn) via ruby-core" <ruby-core@...>
Date:
2025-06-06 19:35:27 UTC
List:
ruby-core #122488
Issue #21158 has been updated by jhawthorn (John Hawthorn).
Status changed from Assigned to Closed
`receive_if` has been removed with the introduction of `Ractor::Port`, so this should no longer be an issue (and it does sound like it was `receive_if` specific)
----------------------------------------
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#change-113677
* Author: NeilW (Neil Wilson)
* Status: Closed
* Assignee: ractor
* 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
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When using the conditional receive example from the Ractor documentation (either as a script, or within irb)
<pre>
r = Ractor.new do
val = Ractor.receive_if{|msg| msg.is_a?(Array)}
puts "Received successfully: #{val}"
end
r.send(1)
r.send('test')
</pre>
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
--
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