当调用者不期望响应时使用`await`

Question

I have a very simple express app which stores information it receives from clients into a database without hardly any processing. Some simplified code to illustrate this:

app.post(ANALYTICS_ENDPOINT, async (req, res) => {
  try {
    await insertToDB(req.body)
    res.status(204).send();
  } catch (err) {
    logger.error(err);
    res.status(500).send();
  }
});

This application is deployed to google cloud run and handles a high volume of requests per second. What we have noticed is that removing the await keyword from the route allows each container to handle more requests, at the downside of not capturing errors - so clients will always receive a 204 .

The other use of await in this would be in insertToDB function which again simplified looks like this:

const insertToDB = async (row) => {
  await dbClient.insert(row);
}

As you can see here we are also using await since this action returns a Promise.

So the question is, should we be awaiting when the caller does not expect a response? And can it be the case that avoiding these awaits we can handle more throughput on our app?

EDIT: There is a similar question here . Yet I think this is different as I am mostly interested in understanding why removing the await allows me to handle 2/3x the number of requests per second.

Answer 1

You should wait because your db call is async , so you must wait the insertion to be made before return to the client.

You can simply use promise resolution to be more concise and clear:

app.post(ANALYTICS_ENDPOINT, async (req, res) => {
    insertToDB(req.body)
    .then(() => res.status(204).send())
    .catch(() => res.status(500).send());
});