In my Python socket program, I sometimes need to interrupt it with Ctrl-C. When I do this, it does close the connection using socket.close().
However, when I try to reopen it I have to wait what seems like a minute before I can connect again. How does one correctly close a socket? Or is this intended?
Yes, this is intended. Here you can read a detailed explanation. It is possible to override this behavior by setting the SO_REUSEADDR option on a socket. For example:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) works, BUT you should use that right after you create the socket. It will not work after .bind()!
udp = socket.socket(socket.AF_INET, / socket.SOCK_DGRAM) / udp.bind((UDP_IP, UDP_PORT)) / udp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) (/ is a new line)
$ ps -fA | grep python
501 81211 12368 0 10:11PM ttys000 0:03.12
python -m SimpleHTTPServer
$ kill 81211
This happens because you trying to run service at the same port and there is an already running application. it can happen because your service is not stopped in the process stack. you just have to kill those processes.
There is no need to install anything here is the one line command to kill all running python processes.
for Linux based OS:
Bash:
kill -9 $(ps -A | grep python | awk '{print $1}')
Fish:
kill -9 (ps -A | grep python | awk '{print $1}')
killall python? Is that not available everywhere? Or does it behave differently?If you use a TCPServer, UDPServer or their subclasses in the socketserver module, you can set this class variable (before instantiating a server):
socketserver.TCPServer.allow_reuse_address = True
(via SocketServer.ThreadingTCPServer - Cannot bind to address after program restart )
This causes the init (constructor) to:
if self.allow_reuse_address:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
A simple solution that worked for me is to close the Terminal and restart it.
Nothing worked for me except running a subprocess with this command, before calling HTTPServer(('', 443), myHandler):
kill -9 $(lsof -ti tcp:443)
Of course this is only for linux-like OS!
For Linux,
ps aux | grep python
This will show you the error. The process number (eg.35225) containing your python file is the error.
Now,
sudo kill -9 35225
This will kill the error process and your problem will be solved.
First of all find the python process ID using this command
ps -fA | grep python
You will get a pid number by naming of your python process on second column
Then kill the process using this command
kill -9 pid
Do nothing just wait for a couple of minutes and it will get resolved. It happens due to the slow termination of some processes, and that's why it's not even showing in the running processes list.
run the command
fuser -k (port_number_you_are _trying_to_access)/TCP
example for flask: fuser -k 5000/tcp
Also, remember this error arises when you interput by ctrl+z. so to terminate use ctrl+c
tcp instead of TCP!I faced similar error at odoo server and resolved that with these simple following steps:
Paste following code in terminal
ps -fA | grep python
You will get a pid number. Now copy the pid number from second column of terminal output.
Then write as below
kill -9 pid
The terminal will restart and then the command
flask run
Will work fine! Thank you
I tried the following code to settle the issue:
sudo lsof -t -i tcp:8000 | xargs kill -9
Use the following command to determine which process is using the port (replace PORT with the actual port number your application is trying to use, e.g., 8000):
sudo lsof -i :PORT
Once you have the PID, terminate it using the kill command:
sudo kill -9 PID
You can do it using a single command as well
sudo kill -9 $(sudo lsof -t -i :PORT)
I had the same problem (Err98 Address already in use) on a Raspberry Pi running python for a EV charging manager for a Tesla Wall Connector. The software had previously been fine but it stopped interrogating the solar inverter one day and I spent days thinking it was something I'd done in python. Turns out the root cause was the Wifi modem assigning a new dynamic IP to the solar inverter as as result of introducing a new smart TV into my home. I changed the python code to reflect the new IP address that I found from the wifi modem and bingo, the issue was fixed.
The cleanest way to make the socket immediately reusable is to follow the recommendation to first shutdown the client end (socket) of a connection, and make sure the server's end shuts down last (through exception handling if needed).
This might well mean that the server end runs forever.
This is not a problem if that "forever" loop pauses execution, e.g. read from socket.
How you "break" that "forever" loop is up to you as server admin, as long as there are no clients (apart from obvious system level exceptions)
in Terminal
Check PID of program:
$ netstat -tulpn
# output:
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
#...
udp 0 0 127.0.0.1:20001 0.0.0.0:* 2859/python
in this case port: 20001, so PID is 2859
terminate this port:
$ kill -9 2859
sudo pkill -9 python
try this command
