You are on M/S. You could be doing "Echo Hello World" and nothing else and
get Deadline Exceeded Errors. Maybe not quite but if you have any imports
that use Memcache than you would.

M/S has Zero advantage at this point.


-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Cezary Wagner
Sent: Tuesday, January 17, 2012 1:37 AM
To: Google App Engine
Subject: [google-appengine] Re: Why are several production issues related to
DeadlineExceededErrors being ignored?

Brandon,

I am doing service management/development many years and your explanation
not convince me since it not show partially valid root cause - I think so -
see why it not convincing.

Low availability is a fact see report again it random for same thing:
2012.01.14      26      1       1       3.152   96.154 %
2012.01.15      47      1       1       4.937   97.872 %
2012.01.16      48      4       5       3.699   89.583 %
2012.01.17      20      0       0       1.699   100 %

Now it looks that it works but I try to open some test pages and it opens
slowly comparing to previous week. TODAY customer experience is still bad -
I do some optimization it visible in times.

You said that it could matter on/have root cause:
1. Configuration of application - why it is RANDOM - once something loads
once not loads - same configuration should give same results.

2. Instance die early if I hit memory limit - good point but not see in log
any message about memory and application is much below 48M - it should not
die - why it is RANDOM.

3. Master/Slave is NOT ROOT CAUSE since DeadlineExceededError occcurs before
any datastore will be touched so there is not impact - are you agree with
that?

4. If Master/Slave is not supported by Google is there any information that
is not supported and from which date?

QUICK example of DeadlineExceededError (dead in imports):
<class 'google.appengine.runtime.DeadlineExceededError'>:
Traceback (most recent call last):
  File "/base/data/home/apps/wcinamy/1-9-9-6.356145314073492481/
frontend/web/order_in_restaurant.py", line 20, in <module>
    from frontend.web.cache import restaurant_menu as cache_restaurant_menu
  File "/base/data/home/apps/wcinamy/1-9-9-6.356145314073492481/
frontend/web/cache/restaurant_menu.py", line 4, in <module>
    from google.appengine.api import memcache

On Jan 17, 12:19 am, "Brandon Wirtz" <[email protected]> wrote:
> If it is a software / configuration issue in your setup then it is not
> down time.
>
> If you have errors on M/S you are on your own.
>
> Instances die early if you hit the soft memory limit. Likely if you
> have load time issues you have memory usage issues as well.
>
>
>
>
>
>
>
> -----Original Message-----
> From: [email protected]
>
> [mailto:[email protected]] On Behalf Of Cezary Wagner
> Sent: Monday, January 16, 2012 2:37 PM
> To: Google App Engine
> Subject: [google-appengine] Re: Why are several production issues
> related to DeadlineExceededErrors being ignored?
>
> Brandom,
>
> I think that problem of DeadlinesExceeds is different:
> 1st of GAE availability is not measure considering DeadlinesExceeds -
> it will be rather not 100%. If it not monitored it has not impact on
quality.
> Am I wrong?
> This is data for the last week:
> Day     Total checks    Outages Failed checks   Avg. response time
> Uptime
> 2012.01.14      26      1       1       3.152   96.154 %
> 2012.01.15      47      1       1       4.937   97.872 %
> 2012.01.16      47      4       5       3.657   89.362 %
>
> 2nd My code without changes through months becomes slower/not faster -
> I have optimized code and it works not faster - on SDK it executes
> 5s-1s (excluding load time) see above results from production. It
> could be suffered with imports but why it once loads and once not
> loads it random - it should not load every time or it problem with
> balance/resource - why IT IS RANDOM?
>
> 3rd Instance DIES just after load not survive 15min period - instance
> was load for 1 min than it dies - that is some problem or lack of
> balance/resource?
>
> 4rd Maybe master/slave has impact?
>
> 5th The application not works in my case under low traffic EARLY DIES
> of INSTANCES and DeadlinesExceeds kills 3%-10% of customer
> traffic(stats above)
> - I am imagine that GAE works some for higher traffic with exception
> that number of errors will be lower - maybe - but how achieve high
> traffic if it not works on lower?
>
> Please answer to question or propose other solution - GAE concept is
> good but the current my customers experience is not excellent.
>
> On 16 Sty, 18:58, "Brandon Wirtz" <[email protected]> wrote:
> > I agree multiple imports is not supposed to be a problem, but I have
> > seen it cause issues, or seen issues be resolved by not doing it.
>
> > Remember that the Google Implementation of Python has its own
> "Specialness"
> > and what is true in traditional python is not always quite the same
> > in GAE land.
>
> > From: [email protected]
> > [mailto:[email protected]] On Behalf Of Karl Rosaen
> > Sent: Monday, January 16, 2012 7:32 AM
> > To: [email protected]
> > Subject: Re: [google-appengine] Re: Why are several production
> > issues related to DeadlineExceededErrors being ignored?
>
> > Brandon, thanks so much for taking the time to put together the
> > video, very helpful.
>
> > The key insight seem to be: time spent in the queue waiting for a
> > frontend counts towards the limit for a DeadlineExceedError. This
> > seems silly - seems to me user visible latency, and framework level
> > timeout enforcement should be decoupled in this case. But good
> > insight and glad to better understand this behavior. This also makes
> > me wonder what the benefit of having 'auto' for max pending latency
> > would ever be - I'm going to slide mine down to ~1s.
>
> > One quibble about your advice for 'avoid importing code more than once':
> > this shouldn't be a major issue in python unless you are importing a
> > module from within a function that is called several times:
>
> > Although Python's interpreter is optimized to not import the same
> > module multiple times, repeatedly executing an import statement can
> > seriously affect performance in some circumstances.
>
> >http://wiki.python.org/moin/PythonSpeed/PerformanceTips#Import_Statem...
> > rhead
>
> > Just wanted to clarify that one needn't fret about the same utility
> > module being imported from two modules or anything like that.
>
> > Karl
> > --
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