Properly stopping, waiting, and reseting a node.js heroku process

Question

I haven't deployed yet, but I'm not sure how to do this.

I have an app that uses a lot of background processes. That is, even after a response is sent, there are still functions associated with that response executing in the background. Thus, I want to do something like this:

var server = http.createServer(app).listen(80)

process.on('SIGINT', function () {
  server.close()
  setTimeout(function () {
    process.exit()
  }, 30000) // Wait 30 seconds before exiting
})

I'm not sure if this is correct or not. More assumptions:

• These background processes are crucial. However, they'll probably take 1-2 seconds, not 30 seconds. Still, I want to put a 30 second delay just for safety.
• This should work for both restarting the process (say, with forever) and stopping the process
• What signals does Heroku (or any other process) send to node.js through process? Would I have to handle them any differently?
• Would I handle uncaughtException any differently?

Thanks

Answer 1

Got it. Heroku sends a SIGTERM signal when shutting down. If the process doesn't exit in 10 seconds, then it sends a SIGKILL signal. Thus, the following is sufficient:

process.on('SIGTERM', server.close.bind(server))

https://devcenter.heroku.com/articles/dynos#graceful-shutdown-with-sigterm

Assuming 10 seconds is enough for the background processes to complete.

Basically, send a "close" signal x seconds before a "exit" signal and you should be good.