Javascript async how to make main thread stop to wait for result? [duplicate]

Javascript async and await is confusing the heck out of me. I am just trying to a simple DB query and return the result. Here I am passing in userId as a reference to an object to modify. and once I query the the statement, I want to add result into userId and print it out.

db.connect();

async function main(userIds) {
  try {
    const query = util.promisify(db.query).bind(db);
    await query("select distinct ownerId from ListingTbl")
      .then(result => {
        const rows = JSON.parse(JSON.stringify(result));
        for (let i = 0; i < rows.length; i++) {
          const r = JSON.parse(JSON.stringify(rows[i]));
          userIds.add(r.ownerId);
          console.log("done")
        }
      })
      .catch(e => {
        throw e;
      });
  } catch (e) {
    throw e;
  }
}

var userIds = new Set();
main(userIds);
console.log("OK");
console.log(userIds);
db.end();

But here I am getting empty userId? I understand await does not block main thread. But then how do I block the main thread from execution?

OK
Set {}
done