Ruby TCPSocket keeps losing connection - ruby

Question

I have a client and server. I start up the server, and run the client, and the first time it works fine. The second time I run the client(without restarting the server), the client appears to hang. Can anyone see what is wrong?
I have a client:
# Code example originated from p069dtclient.rb at http://rubylearning.com/satishtalim/ruby_socket_programming.html
require 'socket'
x = 0;
streamSock = TCPSocket.new( 'localhost', 20000 )
while x &lt 10
streamSock.send( "Hello #{x}",0 )
str = streamSock.recv( 100 )
puts "#{x} " + str
x=x+1
end
streamSock.close
And server:
# p068dtserver.rb
require "socket"
dts = TCPServer.new('localhost', 20000)
s = dts.accept
print(s, " is accepted\n")
loopCount = 0;
loop do
Thread.start(s) do
loopCount = loopCount + 1
lineRcvd = s.recv(1024)
if ( !lineRcvd.empty? )
puts("#{loopCount} Received: #{lineRcvd}")
s.write(Time.now)
end
end
end
s.close
print(s, " is gone\n")

Answer 1

Each connection to the server requires a separate accept call in order to be received. What's happening is that you're accepting the first, working with it, and then effectively terminating while leaving the socket in a listening state. This means connections will be opened, but not accepted, so they hang as you describe.
You might be better off using a more robust server framework. EventMachine (http://rubyeventmachine.com/) is a little tricky to learn, but is far more powerful than a roll your own solution.
Here's a quick fix that might help:
require "socket"
dts = TCPServer.new('localhost', 20000)
while (s = dts.accept)
print(s, " is accepted\n")
loopCount = 0;
loop do
Thread.start(s) do
loopCount = loopCount + 1
lineRcvd = s.recv(1024)
if ( !lineRcvd.empty? )
puts("#{loopCount} Received: #{lineRcvd}")
s.write(Time.now)
end
end
end
s.close
print(s, " is gone\n")
end
Now the accept call is wrapped in a loop so more than one connection can be processed.