Failed .connect() hangs Node for 30 seconds

[salieri]

Tested on 5.0.1 and Node 8.9.4

const mongoose = require( 'mongoose' );
const m = new mongoose.Mongoose();

m.connect( 'mongodb://thisdoesntexist:27017' )
  .then(
    () => { console.log( 'Success!' ); },
    ( err ) => { console.error( err ); }
  );

Results:

1. Promise is rejected pretty much immediately. (As expected)
2. Node.js process hangs (=does not exit) for 30 seconds. (Not expected)

Intuitive expectation would be that connection process comes to an end when the .connect() promise is rejected. Seems like something keeps going on in the background after that, though.

[sobafuchs]

sorry I've deleted my previous comment, i was able to reproduce this actually. To clarify, the node process in this script shouldnt hang for 30 seconds, it should exit immediately. I've even tried passing reconnectTries: 0 to the connection options, and it still hangs:

const mongoose = require( 'mongoose' );
const m = new mongoose.Mongoose();

m.connect( 'mongodb://thisdoesntexist:27017', { reconnectTries: 0, useMongoClient: true } )
  .then(
    () => { console.log( 'Success!' ); },
    ( err ) => { console.error( err ); }
  );

[vkarpov15]

Tracked this down to a bug in the mongodb driver and put in a patch with some questions, see mongodb-js/mongodb-core#275