How can I setup a global DeadlineExceededError handler?

I'd like to catch and handle DeadlineExceededError so users don't see the standard "Server Error" page that App Engine throws by default.

I know that DeadlineExceededErrors are not caught when overriding handle_exception in your request handler (we already do this).

I have tried, unsuccessfully so far, to use the custom error_handlers app.yaml configuration like so:

error_handlers:
  - error_code: timeout
    file: timeout.html

...but that also doesn't seem to catch DeadlineExceededErrors, unless I'm doing something wrong.

I am aware that I can use the following pattern to catch DeadlineExceededErrors inside particular request handlers:

class MainPage(webapp.RequestHandler):
    def get(self):
        try:
            # Do stuff...
        except DeadlineExceededError:
            # Many Whelps! Handle it!

...but I would like to avoid adding this to every single request handler in my application.

How can I global开发者_开发技巧ly catch these elusive suckers?

---

One possible solution is to use webapp2, which is a pretty neat framework as it is and has a lot of useful stuff over the original webapp. With webapp2, you can handle the exception in the handle_500 method, as follows:

def BaseHandler(webapp2.RequestHandler):
    def handle_500(request, response, exception):
        if isinstance(exception, DeadlineExceededError):
            response.write('Deadline exceeded!')
        else:
            response.write('A server error occurred!')

        logging.exception(exception)
        response.set_status(500)