Hi,

Seems like you are also doing some heavy module importing.  You could be
able to trim that down as well.

-Marzia

On Thu, Dec 18, 2008 at 1:57 PM, Derrick <[email protected]> wrote:

>
> Here is what I get from the profile of a query that does not exceed
> the deadline, but comes close:
>
> ncalls  tottime  percall  cumtime  percall filename:lineno(function)
>    15/13    0.299    0.020    1.018    0.078 {__import__}
>       16    0.217    0.014    0.235    0.015
> {google3.apphosting.runtime._apphosting_runtime___python__apiproxy.Wait}
>
> Does this mean that I am making 16 datastore requests and that I need
> to cut down on the number of such requests?
>
> On Dec 18, 1:13 pm, Marzia Niccolai <[email protected]> wrote:
> > This means your app is taking more than 10 seconds to respond to a
> request.
> > Try processing less data per request, or work on streamlining the way
> that
> > you process the data during a request.
> >
> > -Marzia
> >
> > On Thu, Dec 18, 2008 at 12:48 PM, Derrick <[email protected]>
> wrote:
> >
> > > I am getting <class 'google.appengine.runtime.DeadlineExceededError'>
> >
> > > On Dec 18, 12:12 pm, Marzia Niccolai <[email protected]> wrote:
> > > > Hi Derrick,
> >
> > > > What DeadlineExceedError message are you getting, there are a few
> > > different
> > > > deadlines you can run in to with App Engine.
> >
> > > > The most common would be the request deadline.  Any given request
> with
> > > App
> > > > Engine must be completed within 10 seconds.  This is the runtime
> > > > DeadlineExceededError
> >
> > > > Various APIs, like the datastore and URLFetch also have deadlines to
> > > ensure
> > > > that those calls return within the overall request deadline. If you
> are
> > > > running in to this deadline, you will get the
> > > > apiproxy_errors.DeadlineExceededError.
> >
> > > > The problem shouldn't have anything to do with indexing, since simple
> > > > queries indexes are automatically generated, there is no need specify
> > > them
> > > > in the index.yaml (see this article:
> > >http://code.google.com/appengine/articles/index_building.html)
> >
> > > > From your description I can imagine the problem is either you are
> > > requesting
> > > > too much information from the datastore (running in to
> > > > apiproxy_errors.DeadlineExceededError) in one request.  The amount of
> > > data
> > > > you can return in a query will depend on the size and shape of your
> data,
> > > > but you can test this by reducing the amount of data you query for in
> one
> > > > call.
> >
> > > > The other issue I can see is that you are just taking too long to
> return
> > > the
> > > > entire request.  This probably happens because it takes too long to
> > > process
> > > > all of your results before the request deadline.
> >
> > > > Generally in such a case we'd suggest profiling your application
> which
> > > will
> > > > indicate on which calls, and for how long, your app spends it's time.
> > >  Some
> > > > good information on profiling can be found in our FAQ:
> > >http://code.google.com/appengine/kb/commontasks.html#profiling
> > > > Screencast:
> > > > Optimizing Your App: Profiling and Memcachehttp://
> > >www.youtube.com/watch?v=Zip1G6-NiMM
> > > > And the Google I/O talk 'Building a Production Quality Application on
> > > Google
> > > > App Engine:
> > >http://sites.google.com/site/io/best-practices---building-a-productio.
> ..
> >
> > > > -Marzia
> >
> > > > On Thu, Dec 18, 2008 at 10:39 AM, Derrick <[email protected]>
> > > wrote:
> >
> > > > > I am consistently getting Deadline exceeded messages.  The problem
> is
> > > > > that my individual requests are trivial: do a query or two to
> > > > > BigTable, serialize the results, and return them.
> >
> > > > > So, what could be causing these messages.  How are deadlines
> actually
> > > > > measured on app engine?
> >
> > > > > In my case, I am sending a number (10-50) of requests in parallel.
> > > > > Each individual request retrieves a single row in a table plus one
> or
> > > > > two rows in related tables.
> >
> > > > > I would guess that that CPU time usage is measured by interrupting
> the
> > > > > thread serving a request at regular intervals.   The question is,
> how
> > > > > does this interrupt ascertain whether a CPU deadline has been
> > > > > exceeded.
> >
> > > > > I hypothesize that when the poller wakes up, it checks to see which
> > > > > application has the cpu, and adds a tick to the count for that
> user.
> > > > > If the same application is using the CPU as the previous  time the
> > > > > poller awoke, then the poller checks to see if the tick count
> exceeds
> > > > > the deadline. If so, it initiates a deadline exceeded message and
> > > > > terminates the request.
> >
> > > > > If this is the algorithm, then it is very problematic for me. Will
> > > > > someone from the Google App Engine team explain to us the workings
> of
> > > > > the Deadline measuring algorithm so that we can adjust our
> application
> > > > > for work on the platform.
> >
> > > > > Also, could the problem have anything to do with indexing?  Our
> > > > > queries are dirt simple: a single query parameter, so we do not
> > > > > generate indices for them manually.
> >
>

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