Bug #19039: Closing an IO being select'ed in another thread does not resume the thread

• Status: Open
• Assignee: -
• Target version: -
• ruby -v: ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux]
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN

[mame (Yusuke Endoh)]

Is this intentional?

r1, w1 = IO.pipe
r2, w2 = IO.pipe

Thread.new do
  select([r1, r2])
  p :ok
end

sleep 1

p r1.close
# expected: closing r1 resumes select([r1, r2]) in the thread
# actual:   select([r1, r2]) continues to wait

sleep 1
w2 << "foo"
# Making r2 readable resumes select([r1, r2])
# And it raises an exception: closed stream (IOError)

sleep 1

Incidentally, IO#read is resumed by closing the IO.

r1, w1 = IO.pipe

Thread.new do
  r1.read
  p :ok
end

sleep 1

p r1.close
# Closing r1 resumes r1.read in the thread
# And it raises: stream closed in another thread (IOError)

sleep 1

[mame (Yusuke Endoh)]

• Related to Bug #18455: `IO#close` has poor performance and difficult to understand semantics. added