io_select.rb

def with_pipe
  read, write = IO.pipe
  yield read, write
ensure
  read.close if read rescue nil
  write.close if write rescue nil
end

with_pipe do |read, write|
  thread = Thread.new do
    puts IO.select(nil, nil, [write]).include?(write)
  end
  write.close
  read.close
  thread.join
end