of tornado and blocking code

Question

I am trying to move away from CherryPy for a web service that I am working on and one alternative that I am considering is Tornado. Now, most of my requests look on the backend something like:

• get POST data

• see if I have it in cache (database access)

• if not make multiple HTTP requests to some other web service which can take even a good few seconds depending on the number of requests

I keep hearing that one should not block the tornado main loop; I am wondering if all of the above code is executed in the post() method of a RequestHandler , does this mean that I am blocking the code ? And if so, what's the appropriate approach to use tornado with the above requirements.

Answer 1

Tornado comes shipped with an asynchronous (actually two iirc) http client ( AsyncHTTPClient ). Use that one if you need to do additional http requests.

The database lookup should also be done using an asynchronous client in order to not block the tornado ioloop/mainloop. I know there are a couple of tornado tailor made database clients (eg redis , mongodb ) out there. The mysql lib is included in the tornado distribution.