Where to end the mysql pool connection on nodejs?

I'm using MySQL on Nodejs. I'm using mysql pool to create the connection:

Var mysqk = require ('mysql');
Var pool = mysql.createPool ({my configs});

My question is: Where in the app will I use pool.end() as reported in the documentation?

For example: in my www file, I created a code to release other things as I have pointed in de code. Should I use pool.end() there?

var app     = require('../app');
var debug   = require('debug')('cancela:server');
var http    = require('http');
var port = normalizePort(process.env.PORT || '4000');
app.set('port', port);
var server = http.createServer(app);

// my app codes...
..
.
.

process.once('SIGTERM', end);
process.once('SIGINT', end);

function end() {

    server.close(function(err){

    if(err) throw err();

        // Should I end the Pool connection here?  <<<<<<===================================
        // pool.end(function (err) {
        //   // all connections in the pool have ended 
        // });

        console.log('Server endded!');        

        /* exit gracefully */
        process.exit();
    });
}