Question

I have a Node.js application that contains an http(s) server.

In a specific case, I need to shut down this server programmatically. What I am currently doing is calling its close() function, but this does not help, as it waits for any kept alive connections to finish first.

So, basically, this shuts down the server, but only after a minimum wait time of 120 seconds. But I want the server to shut down immediately – even if this means breaking up with currently handled requests.

What I can not do is a simple

process.exit();

as the server is only part of the application, and the rest of the application should remain running. What I am looking for is conceptually something such as server.destroy(); or something like that.

How could I achieve this?

PS: The keep-alive timeout for connections is usually required, hence it is not a viable option to decrease this time.

Answer 1

The trick is that you need to subscribe to the server’s connection event which gives you the socket of the new connection. You need to remember this socket and later on, directly after having called server.close(), destroy that socket using socket.destroy().

Additionally, you need to listen to the socket’s close event to remove it from the array if it leaves naturally because its keep-alive timeout does run out.

I have written a small sample application you can use to demonstrate this behavior:

// Create a new server on port 4000
var http = require('http');
var server = http.createServer(function (req, res) {
  res.end('Hello world!');
}).listen(4000);

// Maintain a hash of all connected sockets
var sockets = {}, nextSocketId = 0;
server.on('connection', function (socket) {
  // Add a newly connected socket
  var socketId = nextSocketId++;
  sockets[socketId] = socket;
  console.log('socket', socketId, 'opened');

  // Remove the socket when it closes
  socket.on('close', function () {
    console.log('socket', socketId, 'closed');
    delete sockets[socketId];
  });

  // Extend socket lifetime for demo purposes
  socket.setTimeout(4000);
});

// Count down from 10 seconds
(function countDown (counter) {
  console.log(counter);
  if (counter > 0)
    return setTimeout(countDown, 1000, counter - 1);

  // Close the server
  server.close(function () { console.log('Server closed!'); });
  // Destroy all open sockets
  for (var socketId in sockets) {
    console.log('socket', socketId, 'destroyed');
    sockets[socketId].destroy();
  }
})(10);

Basically, what it does is to start a new HTTP server, count from 10 to 0, and close the server after 10 seconds. If no connection has been established, the server shuts down immediately.

If a connection has been established and it is still open, it is destroyed.
If it had already died naturally, only a message is printed out at that point in time.