multithreaded server in python

Question

I have a server-client application written in python. Everything worked fine but I wanted to make the server multi threaded and everything crashed.

Here is part of the code for the server:

host = 'localhost'
port = 10001

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

class ClientThread(threading.Thread):

def __init__(self, ip, port, socket):
    print '5'
    threading.Thread.__init__(self)
    self.ip = ip
    self.port = port
    self.socket = socket
    print "[+] New thread started for "+ip+":"+str(port)

def __run__(self):
    while  True:
        try:
            #conn, addr = sock.accept()
            print >>sys.stderr, "Connection from : "+ip+":"+str(port)
            print '6'

            #reqCommand = conn.recv(1024)
            reqCommand = self.recv(1024)
            print '7'
            command = reqCommand.split(' ', 1)  # get <<filename>>
            print '8'
            reqFile = command[1]    # takes the name of the file
            reqCommand = command[0]
            print '9'
            encFile = reqFile + "_enc"
            print >>sys.stderr, 'Client> %s' % (reqCommand)

            if (reqCommand == 'get'):
        pass

            try:
                os.remove(encFile)  # removes the encrypted file
            except OSError, e:  
                print ("Error: %s - %s." % (e.filename,e.strerror))

            print >>sys.stderr, 'successfully finished'
            print >>sys.stderr, 'waiting for new connections...' 
        finally:
        # clean up connection
            self.close()


while True:
    sock.listen(4)
    print "\nListening for incoming connections..."
    (conn, (ip, port)) = sock.accept()
    print '1'
    newthread = ClientThread(ip, port, conn)
    print '2'
    newthread.start()
    print '3'
    threads.append(newthread)
    print '4'

When I type in the client: "get " it sends the message to the client but it doesn't receive anything back. In the server as you can see I have a lot of prints to see where it crashes. It prints in the following order: 1 5 2 3 4. + it also prints [+] new thread...

As you can also see I've used self.recv instead of conn.recv (this was a solution that I found on stackoverflow, but it didn't work)

Does anyone have a clue what I'm doing wrong? I mention again that before I've added threads and the class ClientThread everything worked fine. Thanks in advance!

no, sorry. it also prints that. it seems that it doesn't enter __run__() — spoke
– spoke, Commented Oct 26, 2015 at 21:26

asm · Accepted Answer · 2015-10-27 01:29:20Z

1

You have a lot of errors in the code shown.

E.g. self.recv(1024) should probably be replaced with self.socket.recv(1024), and self.close() with self.socket.close()? (since self is an instance of ClientThread/Thread, not a socket). I also think run method should be named just run (not __run__), and if you do a close() in the finally in run() the second time while True is executed connction will be already closed.

In addition to that, large chunks are missing, e.g. all the imports, and a call to bind() - e.g. something like sock.bind((socket.gethostname(), port))

Other than that and assuming all these errors are fixed, it seems that it should do what it is supposed to.

edited Oct 27, 2015 at 1:29

answered Oct 26, 2015 at 21:53

asm

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