[Tutor] seeking help to a problem w/ sockets

Jeff Younker jeff at drinktomi.com
Mon Apr 28 00:47:42 CEST 2008

It sounds like a process is still listening on the port.   If you're
on a Unix system then you can use lsof (aka list open files) to
locate the process holding on the socket. Killing the process
should free the socket.

Also, you don't have to close the socket after every connection
completes.  Try looking at the SocketServer module.  It takes
care of a lot of the details for you.

- Jeff Younker - jeff at drinktomi.com -

On Apr 26, 2008, at 5:56 PM, James Duffy wrote:

> I have a problem w/ a file transfer receiver. They way it works is  
> it binds a port for incoming transfer , when the file transfer is  
> complete. It closes the connection and the socket, then loops back  
> and restarts the bind and listen. I have it set so that the socket  
> is reuseable, which is why this works. However, if the program that  
> is using this function is closed while listening, it appears that it  
> does not ”un-bind” because when the program is reopened and a listen  
> attepted to start I get a “port already in use” error. Only a reboot  
> fixes this issue. This code is imported into a main GUI script. We  
> have it set to execute some cleanup functions on exit, I need a  
> function that can dig down to the thread the listener is running in,  
> stop the listen and close the connection and socket. I basically  
> need to get to the close function and then stop the while loop.  
> Thanks in advance for any help anyone can give. My code for the  
> listener class follows:
> class Reciever ( Thread ):   # the reciever class for the test tool,  
> runs as a separate thread from the main program
>     def __init__( this ):
>         Thread.__init__( this )
>     def run(this):
>         this.process()
>     def bindsock( this ):   # create a new socket, bid the socket to  
> the port, listen until connection recieved
>         this.Lport=listen
>         this.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>         this.sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
>         this.sock.bind(('',this.Lport))
>         this.sock.listen(1)
>         print "Listening on port " +str(this.Lport)
>     def acceptsock( this ): #when connection is incoming, accept the  
> connection
>         this.conn, this.addr = this.sock.accept()
>         print 'Got connection from', this.addr
>     def transfer( this ):   #when connection is full established,  
> begin data download
>         global filenumber
>         print 'Starting media transfer '
>         openfile="XMLrecieved"+str(filenumber)+".xml"
>         f = open(openfile,"wb") #create and open a new file for  
> writing incoming data to
>         while 1:
>             data = this.conn.recv(1024)   #check for incoming data
>             if not data: break         #if not present, break the loop
>             f.write(data)       #if data is present, write it to  
> file and loop back
>         f.close()  #when loop is broken, close the file
>         print "Got XML file:" + openfile
>         print 'Closing media transfer'
>         filenumber = filenumber + 1
>     def close( this ):  #close all connections and sockets
>         this.conn.close()
>         this.sock.close()
>     def process( this ):     #this is the loop of the thread, it  
> listens, receives, closes then repeats until entire program is closed
>         while 1:
>             this.bindsock()
>             this.acceptsock()
>             this.transfer()
>             this.close()
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor

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