Next.js：发送 HTTP 响应后如何执行代码？

Question

In Express you can execute code after sending an HTTP response like this:

res.send()
await someAsyncFunction() // imagine this takes a very long time

In Next.js, at least when testing code in a local environment, the above works the same as express. However, once deployed on Vercel, the above code seems to stop execution after sending the HTTP response. I don't know if this is just because that's how their serverless functions are set up or what. So I'm forced to rearrange it like this:

await someAsyncFunction() // imagine this takes a very long time
res.send()

The problem with ordering it like that is if the async function is very slow, the response could time out before it gets sent back. There are situations where that is bad. Say I need to send a bunch of emails using a rate-limited API. That can take a long time. I need to send a HTTP response right away before moving on to the very slow process of sending all the emails.

Answer 1

I haven't been able to find explicit documentation explaining this behavior, but this GitHub discussion appears to confirm that you cannot execute code after sending an HTTP response if you are deploying on Vercel: https://github.com/vercel/next.js/discussions/14077

Thus I am stuck sending the response last.