bug.rb

$ cat bug.rb 
require "socket"

s, i = [], 0

loop do
   s << TCPServer.new("localhost", 5000)
   p i += 1
   sleep 1 
end

$ ruby bug.rb 
1
2
3
bug.rb:6:in `initialize': Address already in use - bind(2) (Errno::EADDRINUSE)
	from bug.rb:6:in `new'
	from bug.rb:6
	from bug.rb:5:in `loop'
	from bug.rb:5
$