Prevent request timeout with long requests

Question

I have a Rails Controller on Heroku where I send emails in a loop, and respond to the user with some information on which email address the emails were sent to.

While this works when only a few (~40) emails need to be sent out, the request times out when more there are more than just a few emails to be sent out (e.g. > 40).

Heroku states in their guides that requests must respond with at least one byte within 30 seconds: https://devcenter.heroku.com/articles/request-timeout

While I know this is not the best way to achieve this, I'm currently trying to figure out how to do this in Ruby.

If this were a PHP app, I could do an echo before entering the loop, and then keep echoing something in every iteration. How do I achieve something similar in rails?

Answer 1

Your best bet is to not do the mailing before sending the response back. You will have better luck first adding the job to one of Heroku's many available worker queues, then kicking to a monitoring page that displays the job progress and updates itself periodically. If you are trying to avoid using one of those queue services, for budget reasons, you may be able to accomplish the same thing using a new thread, instead of a queue. Either way, this technique will scale better, as well as being able to recover from failure more easily as well.

As you appear to already know that your proposed solution is not the ideal solution, I will also try to answer your exact question. You may be able to make HTTP streaming work for this. I would recommend checking out http://railscasts.com/episodes/266-http-streaming.