I came across this (
http://code.google.com/appengine/docs/python/taskqueue/overview-push.html#Push_Queues_and_Backends).
Which suggests that I should be able to use a specific backend instance.
Not only was the backend started (really, enabled), but it was up and
running too, from serving up a request recently. In fact, I'm enqueueing
the taskqueue request from the backend itself (the backend logs prove it
too). I tried your method too (using just the backend name, and no instance
prefix), and that didn't work either. The only difference is that I'm not
passing any "params" parameter in the taskqueue.add() call. The request is
just meant to be a trigger and does not carry any data. Perhaps the app
engine scheduler thinks that my backend is busy (cause it was processing the
current request which enqueued the new taskqueue request), and that causes
it to send the request to a front-end instance. Maybe I should send the
taskqueue rquest with a "countdown" set to a comfortable 10 seconds or
something.
Here's the snippet from the link above:
Push tasks typically must finish execution within 10 minutes. If you have
push tasks that require more time or computing resources to process, you can
use App Engine Backends to process these tasks outside of the normal limits
of App Engine applications. Backends are addressable. When you create the
push task, all you need to do is address it to the URL of the backend you
wish to process it. The following code sample demonstrates how to create a
push task addressed to an instance 1 of a backend named backend1:
from google.appengine.api import taskqueue
...
def post(self):
key = self.request.get('key')
# Add the task to the default queue.
taskqueue.add(url='/path/to/my/worker/', params={'key':
key}, target='1.backend1')
On Fri, Sep 9, 2011 at 4:10 PM, Steve Sherrie <[email protected]>wrote:
> **
> I'm able to direct tasks to the backends using the *target* arg as in your
> example. And the backend state is 'start' when you're trying this?
>
> Are you directing toward a specific backend instance (*N.backend_name*) or
> just to *backend_name*? I am doing the latter.
>
>
> Steve
>
>
>
> On 11-09-09 05:00 PM, Rishi Arora wrote:
>
> Thanks. Yes that worked for me. It just seems that backend documentation
> isn't very intuitive. I couldn't tell from any of the online docs that
> simply adding a backend to backends.yaml won't configure a backend for you.
> It won't show up in the backends section of the admin console until you
> execute appcfg.py update backends.
>
> Another non-intuitive behavior - probably only for dynamic backends. The
> admin console has a start/stop button. But obviously, if you hit start, the
> dynamic backend won't actually start. That's clear from the documentation.
> But, if you hit "stop", it almost looks like that the backend is made
> inaccessbile. It won't process requests, and it won't automatically restart
> on the next request. You have to hit the "start" button first. I think for
> dynamic backends that button should read "enable/disable".
>
> Now the next thing I'm trying to get to work is sending a backend a
> request from a task queue. I'm using the default task queue to do this, and
> simply doing this doesn't work (a front-end instance processes the taskqueue
> request):
>
> taskqueue.add(url=[relative path to request handler], method='POST',
> target=[backend name from app.yaml])
>
> Modifying the above statement to specify the entire URL for the backend
> in the "target" parameter does not help either - the taskqueue request is
> still processed by a front-end instance. I also tried just getting rid of
> the "target" parameter, and specifying the entire url in the "url" parameter
> i.e. url='https://backend.appid.appspot.com/path/to/requesthandler'. And
> even that did not help. I fear forcing backends to process cron entries
> defined with a full URL like above won't do the trick either.
>
> So is there no way to force a backend to process a request?
>
>
>
> On Fri, Sep 9, 2011 at 3:45 PM, Steve Sherrie <[email protected]>wrote:
>
>> Also, you can do...
>> *
>> *
>> *appcfg.py update **--backends your_app*
>> *
>> *
>> *
>> *
>> Steve
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