python - Multi threaded server send function -

i got multi threaded server code , works when type send client not sending send function work if send data string knows what's problem?

#!/usr/bin/env python  import socket, threading  class clientthread(threading.thread):      def __init__(self, ip, port, clientsocket):         threading.thread.__init__(self)         self.ip = ip         self.port = port         self.csocket = clientsocket         print "[+] new thread started "+ip+":"+str(port)      def run(self):             print "connection : "+ip+":"+str(port)          clientsock.send("welcome server ")          data = "dummydata"          while len(data):             data = self.csocket.recv(2048)             print "client(%s:%s) sent : %s"%(self.ip, str(self.port), data)              userinput = raw_input(">")             self.csocket.send(userinput)          print "client @ "+self.ip+" disconnected..."  host = "0.0.0.0" port = 4444  tcpsock = socket.socket(socket.af_inet, socket.sock_stream) tcpsock.setsockopt(socket.sol_socket, socket.so_reuseaddr, 1)  tcpsock.bind((host, port))  while true:     tcpsock.listen(4)     print "nlistening incoming connections..."     (clientsock, (ip, port)) = tcpsock.accept()      #pass clientsock clientthread thread object being created     newthread = clientthread(ip, port, clientsock)     newthread.start() 

well, can see @ least 1 thing prevent working intended:

def run(self):         print "connection : "+ip+":"+str(port)      clientsock.send("welcome server ") 

clientsock undefined.