I have a Node.js game server and I start it by running nodemon app.js. Now, every time I edit a file the server restarts. I have implemented save and load functions and I want every time the game server restarts (due to the file chages) the game to be saved before restarting so that I can load the previous state after the restart.

Something like this is what I want:

process.on('restart', function(doneCallback) {
   saveGame(doneCallback);
   // The save game is async because it is writing toa file
}

I have tried using the SIGUR2 event but it was never triggered. This is what I tried, but the function was never called.

// Save game before restarting
process.once('SIGUSR2', function () {
     console.log('SIGUR2');
     game.saveGame(function() {
        process.kill(process.pid, 'SIGUSR2');
     });
});

I have a Node.js game server and I start it by running nodemon app.js. Now, every time I edit a file the server restarts. I have implemented save and load functions and I want every time the game server restarts (due to the file chages) the game to be saved before restarting so that I can load the previous state after the restart.

Something like this is what I want:

process.on('restart', function(doneCallback) {
   saveGame(doneCallback);
   // The save game is async because it is writing toa file
}

I have tried using the SIGUR2 event but it was never triggered. This is what I tried, but the function was never called.

// Save game before restarting
process.once('SIGUSR2', function () {
     console.log('SIGUR2');
     game.saveGame(function() {
        process.kill(process.pid, 'SIGUSR2');
     });
});

• javascript
• node.js
• signals
• nodemon

• Did you try github./remy/nodemon/blob/master/doc/events.md nodemon.on('restart',...) ? – crackmigg Commented Apr 14, 2016 at 17:38
• @migg No, didn't have the nodemon package included, will take a look. – XCS Commented Apr 14, 2016 at 17:41
• @migg Nope, that event is not called. – XCS Commented Apr 14, 2016 at 17:54
• So again, I start nodemon from the console mand. – XCS Commented Apr 14, 2016 at 18:02
• 1 @AnandUndavia I don't really remember, I think I didn't manage to make it work on Windows, and what I did was just having saves/snapshopts at a regular interval, if the server failed/restarted I would just load the latest available snapshopt. – XCS Commented Jun 26, 2019 at 8:34

2 Answers 2

Below code works properly in Unix machine. Now, As your saveGame is asynchronous you have to call process.kill from within the callback.

process.once('SIGUSR2', function() {
    setTimeout(()=>{
        console.log('Shutting Down!');
        process.kill(process.pid, 'SIGUSR2');
    },3000);

});

So, your code looks fine as long as you execute your callback function from within the game.saveGame() function.

// Save game before restarting
process.once('SIGUSR2', function () {
     console.log('SIGUR2');
     game.saveGame(function() {
        process.kill(process.pid, 'SIGUSR2');
     });
});

on Windows

run app like this:

nodemon --signal SIGINT app.js

in app.js add code

let process = require('process');

process.once('SIGINT', function () {
  console.log('SIGINT received');
  your_func();
});