From: Florian Frank <flori@...>
Date: 2002-05-27T07:01:43+09:00
Subject: Possible Bug in Ruby?


Hi!

I have observed a very strange behavior of Ruby (1.6.7). I think it has
something to do with threads and sockets. I have written a little script that
can be used to reproduce the problem:

require 'timeout'
require 'socket'

host, port = ARGV.shift.split(/:/)

print "My PID is #$$.\n"
s = nil
print "Connecting...\n"
begin
    timeout(5) do
    s = TCPSocket.new(host, port)
    line = s.readline.chomp
    print "Got line = '#{line}'.\n"
    end
rescue TimeoutError
    print "Timed out!\n"
rescue
    print "Caught exception #{$!.type}: #$!!\n"
ensure
    print "s = #{s}.\n"
    s.close if s
end
print "Press <return> key to exit.\n"
gets

There are four possible cases to connect to a port on some host using
this script (with $ ruby connect.rb host:port).

1. The port is closed. Then an Errno::EINVAL exception is thrown.

2. The port is opened and the listening server (perhaps a sshd on port 22)
sends a line which is received. The socket s is closed in the ensure
code block.

3. The port is opened and the listening server (e. g. a httpd on port 80)
doesn't send anything but waits for a request from the client. The connection
times out after 5 seconds and the socket s is closed in the ensure code
block.

4. The host is not reachable because it is not on the wire. In this case
the connection times out and the socket s is nil and thus cannot
be closed. This would be ok but if you use a program like lsof or fstat
and type "lsof -p $PID" or "fstat -p $PID" you can see that the socket
is in fact opened. It doesn't seem possible to close it anyhow from within
this script.

I don't know where the problem lies but I don't think it has something
to do with timeout.rb but with the thread it uses. Does somebody
have an idea how to fix this?