mysql2 getConnection method is skipped

Question

I have a problem in Nodejs when trying to make a connection with my db via getConnection method. I declared my db variable via require which is a createPool promise(as shown below). when i try to make a connection with that pool via getConnection it skips that code block.

const pool = mysql.createPool({
    host: process.env.DB_HOST,
    user: process.env.DB_USER,
    database: process.env.DB_NAME,
    password: process.env.DB_PASSWORD,
    waitForConnections: true,
    connectionLimit: 10,
    queueLimit: 0
});

const db = pool.promise(); // this is exported

my connection method:

console.log('start');
        const items = [this.idplace,this.idactivity,this.iduser,this.date,this.hour,this.party_size];
        db.getConnection(function(err, conn) {
            if(err) {                                     
                console.log('error when connecting to db:', err);
                db.releaseConnection(conn);
                throw err; 
              } 
            console.log('ok');
            conn.execute(`INSERT INTO reservation(place,activity,customer,date,hour,party_size)VALUES(?,?,?,'?','?',?);`, items);
            db.releaseConnection(conn);
         });
         console.log('end');

and the log is: start end (no sign of the logs inside db.getConnection)

What do you think is the reason of that?