[python] socket.error: [Errno 48] Address already in use

I'm trying to set up a server with python from mac terminal.

I navigate to folder location an use:

python -m SimpleHTTPServer

But this gives me error:

socket.error: [Errno 48] Address already in use

I had previously open a connection using the same command for a different website in a different location in my machine.

Simple solution:

1. Find the process using port 8080:

`sudo lsof -i:8080`

2. Kill the process on that port:

`kill $PID`

PID is got from step 1's output.

I have a raspberry pi, and I am using python web server (using Flask). I have tried everything above, the only solution is to close the terminal(shell) and open it again. Or restart the raspberry pi, because nothing stops that webserver...

This commonly happened use case for any developer.

It is better to have it as function in your local system. (So better to keep this script in one of the shell profile like ksh/zsh or bash profile based on the user preference)

function killport {
   kill -9 `lsof -i tcp:"$1" | grep LISTEN | awk '{print $2}'`
}

Usage:

killport port_number

Example:

killport 8080

By the way, to prevent this from happening in the first place, simply press Ctrl+C in terminal while SimpleHTTPServer is still running normally. This will "properly" stop the server and release the port so you don't have to find and kill the process again before restarting the server.

(Mods: I did try to put this comment on the best answer where it belongs, but I don't have enough reputation.)

Use

 sudo lsof -i:5000

This will give you a list of processes using the port if any. Once the list of processes is given, use the id on the PID column to terminate the process use

 kill 379 #use the provided PID

I am new to Python, but after my brief research I found out that this is typical of sockets being binded. It just so happens that the socket is still being used and you may have to wait to use it. Or, you can just add:

tcpSocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

This should make the port available within a shorter time. In my case, it made the port available almost immediately.

Just in case above solutions didn't work:

1. Get the port your process is listening to:

   $ ps ax | grep python

2. Kill the Process

   $ kill PROCESS_NAME

Simple one line command to get rid of it, type below command in terminal,

ps -a

This will list out all process, checkout which is being used by Python and type bellow command in terminal,

kill -9 (processID) 

For example kill -9 33178

You can also serve on the next-highest available port doing something like this in Python:

import SimpleHTTPServer
import SocketServer

Handler = SimpleHTTPServer.SimpleHTTPRequestHandler

port = 8000
while True:
    try:
        httpd = SocketServer.TCPServer(('', port), Handler)
        print 'Serving on port', port
        httpd.serve_forever()
    except SocketServer.socket.error as exc:
        if exc.args[0] != 48:
            raise
        print 'Port', port, 'already in use'
        port += 1
    else:
        break

If you need to do the same thing for other utilities, it may be more convenient as a bash script:

#!/usr/bin/env bash

MIN_PORT=${1:-1025}
MAX_PORT=${2:-65535}

(netstat -atn | awk '{printf "%s\n%s\n", $4, $4}' | grep -oE '[0-9]*$'; seq "$MIN_PORT" "$MAX_PORT") | sort -R | head -n 1

Set that up as a executable with the name get-free-port and you can do something like this:

someprogram --port=$(get-free-port)

That's not as reliable as the native Python approach because the bash script doesn't capture the port -- another process could grab the port before your process does (race condition) -- but still may be useful enough when using a utility that doesn't have a try-try-again approach of its own.

You can allow the server to reuse an address with allow_reuse_address.

Whether the server will allow the reuse of an address. This defaults to False, and can be set in subclasses to change the policy.

import SimpleHTTPServer, SocketServer
PORT = 8000
httpd = SocketServer.TCPServer(("", PORT), SimpleHTTPServer.SimpleHTTPRequestHandler)
httpd.allow_reuse_address = True
print "Serving at port", PORT
httpd.serve_forever()