Stopping long-running requests in Pylons

Question

I'm working on an application using Pylons and I was wondering if there was a way to make sure it doesn't spend way too much time handling one request. That is, I would like to find a way to put a timer on each request such that when too much time elapses, the request just stops (and possibly returns some kind of error).

The application is supposed to allow users to run some complex calculations but I would like to make sure that if a calculation starts taking too much time, we stop it to allow other calculations to take place.

Answer 1

Rather than terminate a request with an error, a better approach might be to perform long-running calculations in a separate thread (or threads) or process (or processes):

1. When the calculation request is received, it is added to a queue and identified with a unique id. You redirect to a results page referencing the unique ID, which can have a "Please wait, calculating" message and a refresh button (or auto-refresh via a meta tag).
2. The thread or process which does the calculation pops requests from the queue, updates the final result (and perhaps progress information too), which the results page handler will present to the user when refreshed.
3. When the calculation is complete, the returned refresh page will have no refresh button or refresh tag, but just show the final result.