With respect to running stop() during a MM crash – the main function in js/app.js is still attaching to process.on("SIGINT", ...) just upstream of the individual node_helper files. If MM crashes I think it should still call the stop() functions unless the node_helper array gets corrupted. An advantage to cycling through each node_helper would be that you don’t have multiple individual SIGINT listeners that are trying to call a process.exit before the other is done.

I like your stop() function idea but I worry that it won’t be called in the event of an MM crash, in which case anything that should otherwise have run in the stop() routine won’t get called. Listening for SIGINT is a more reliable option in that situation, especially if you have resources that need to be explicitly released.

Full code that wasn’t working here

Working code based on the change request I described here

Thank you for the help, I’m going to chalk it up to a fluke that I’ve spent too much time investigating and now have a work around. It’ll be nice to have a standard clean-up method incorporated in the main code anyways.

I ended up making a tweak to the core and a pull request to work around this:
https://github.com/MichMich/MagicMirror/pull/1058

If this gets incorporated then all you’d need in your node_helper.js is a stop() function:

stop: function() { 
  console.log("[MMM-MyWink] Cleaning Up");
  self.pubnub.removeListener(self.pnListener);
  self.pubnub.unsubscribeAll();
} 

Here’s an example from my MMM-MyWink module:

socketNotificationReceived: function(notification, payload){

    var self = this;

    if (notification === 'MMM-MYWINK-GET-INITIAL-STATUS') {

      // ... edited for brevity

      } else {

        this.config = payload;

        //log into Wink account and set up subscriptions
        this.initialize();

        //set up some cleanup on application exit
        process.on('SIGINT', function () {  
          console.log("[MMM-MyWink] Cleaning Up");
          self.pubnub.removeListener(self.pnListener);
          self.pubnub.unsubscribeAll();
          process.exit();
        });

      } 


    }
  },

Full code here:
https://github.com/jclarke0000/MMM-MyWink/blob/master/node_helper.js

What I am suggesting, in case anyone else developing a module needs this: allow module developers to implement a stop: function() { } in their node_helper.js file that performs any cleanup required. When exiting, the MM app will call this function, if it exists, and each module can gracefully exit on it’s own.

There is a working example of this here: shbatm/MagicMirror@9935d2f

I was assuming I would need the cleanup routine in my module, I was just wondering if there was some routine in the core code that already listened for SIGINT and then called each module’s cleanup function (if there was one)–like it does with each node_helper.js’s start function–that way I would just have to add a function instead of add multiple SIGINT handlers (one in each module).

It’s probably a niche requirement and it’s easy enough to add them for each module that needs one. Just curious if it existed, or was maybe worth adding.

I’ve used the PubNub API in a couple of my modules and I run a routine on SIGINT to remove listeners and subscriptions. Pm2’s exit might take care of nullifying these or it might not, but with by writing the exit routine I can be sure these are taken care of.