EADDRINUSE error if I force kill the process and then try to re-launch it

Question

var arDrone = require('ar-drone');
var PaVEParser = require('./PaVEParser');
var output = require('fs').createWriteStream('./vid.h264');
var client;
var mostRecentFrame;
var frameCounter = 0;

const net = require('net');
const server = net.createServer((c) => {
  // 'connection' listener
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
    c.on('data', (data) => {
    c.write(mostRecentFrame);
    });
});
server.on('error', (err) => {
  throw err;
});
server.listen('/tmp/ard.sock', () => {
  console.log('server bound');
});

process.stdin.on('data', function() {
    console.log("Ending the program, landing the drone and terminating the connection.");
    server.close();
    process.exit();
});

When I force-kill this program, I cannot re-launch it.

daniel@beepboop:~/AR-drone Project$ node test-save-pngs-no-flight.js 
/home/daniel/AR-drone Project/test-save-pngs-no-flight.js:24
  throw err;
  ^

Error: listen EADDRINUSE /tmp/ard.sock
    at Object.exports._errnoException (util.js:1036:11)
    at exports._exceptionWithHostPort (util.js:1059:20)
    at Server._listen2 (net.js:1239:19)
    at listen (net.js:1288:10)
    at Server.listen (net.js:1377:5)
    at Object.<anonymous> (/home/daniel/AR-drone Project/test-save-pngs-no-flight.js:26:8)
    at Module._compile (module.js:556:32)
    at Object.Module._extensions..js (module.js:565:10)
    at Module.load (module.js:473:32)
    at tryModuleLoad (module.js:432:12)

I believe this is because the socket wasn't closed correctly.

How can I make the program close the socket when I force kill it, and
How can I manually close the socket afterwards from the command line?

Edit:

I am using Ubuntu 16.04. By force kill, I mean that I am hitting "control-C" during runtime.

What OS? How are you force killing it? Have you verified that it is not still running by checking system processes? Have you looked at what sockets the system reports as open? — jfriend00, Sep 23 '16 at 14:01
I'm unsure about how to check system processes. Does control-C just put them to sleep? I added the other info. — Daniel Paczuski Bak, Sep 23 '16 at 14:11
You can check the system processes that are running with `ps aux`. You can kill an individual process by typing `kill xxxx` where `xxxx` is the process id you saw in `ps aux`. This is how you clean up a process you don't want running any more. See here http://www.cyberciti.biz/tips/linux-display-open-ports-owner.html for how to list open sockets and the processes that own them. — jfriend00, Sep 23 '16 at 14:21
@jfriend00 This is how it works. Domain sockets are not removed on process exit and that's by design. See the links to the issues on GitHub that I posted in my answer below. — rsp, Sep 23 '16 at 14:27

rsp · Accepted Answer · 2016-09-23T14:19:26.097

2

Yes, this is how it works. This is a shorter example to reproduce it:

var net = require('net');
const server = net.createServer((c) => {
});
server.on('error', (err) => {
  throw err;
});
server.listen('/tmp/x.sock', () => {
  console.log('server bound');
});

You can avoid that problem by running:

server.close();

before the program exits.

In your case you can avoid that problem by handling the SIGINT:

var net = require('net');
const server = net.createServer((c) => {
});
server.on('error', (err) => {
  throw err;
});
server.listen('/tmp/x.sock', () => {
  console.log('server bound');
});
process.on('SIGINT', () => {
  server.close();
  process.exit();
});

EADDRINUSE error if I force kill the process and then try to re-launch it

1 Answers1