You just need to add a try: except: (if you're using Python) to handle
TombstonedTaskError and TaskAlreadyExistsError.
I use a taskadd function that looks like this:
def taskAdd(name,counter,delay=0,wait=.5):
try:
taskqueue.add(name = name,url = '/mytasks/doTask',
countdown = delay, params = {'counter' : counter} )
except (taskqueue.TaskAlreadyExistsError,
taskqueue.TombstonedTaskError), e:
pass
except:
from time import sleep
sleep(wait)
taskAdd(name,counter,delay,2*wait)
Once a task is done.. it adds a new one back to the queue like so:
counter = int(self.request.get('counter')) + 1
taskAdd(name+str(counter),counter)
That way.. if you get any error besides one indicating the Task is already
there.. it just tries to add the task again a little later.
Of course.. you give it whatever delay you want.. in case you don't want it
to start immediately.
On Mon, Feb 22, 2010 at 10:23 AM, Iap <[email protected]> wrote:
> Hi,
>
> In my application, I have to pool the datestore every 3 seconds for
> updating states.
> I implement this pooling into taskqueue as a task.
> For every execution, the task gets the job done and add itself to the
> taskqueue for next execution.
> Something like recursive execution.
>
> The problem is that after a certain period, from one hour to several
> hours,
> the number of tasks grows up. I understand that it is because the
> auto-retry of the taskqueue.
> Because of the TombStonedError, I can not assign name to task for
> preventing the duplication.
> Also, I have no idea to handle the TransientError. The document says
> to retry again later.
> Because this is a background running process, the question is "how to
> be later?",
> Put it in taskqueue! Then, I am like a python which swallow its own tail.
>
> In javascript, ActionScript, there are "setTimeout" and "setInterval"
> for one-time tasks and looping tasks.
> In Twisted/Python, there are reactor.callLater and task.LoopingCall
> for the both too.
>
> How to do looping task in the taskqueue correctly?
>
> Thanks
>
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