Strange import errors in logs (fatal)

[Pamela Fox]

My app went down for 10 minutes, and when I look at the logs, I see a lot of:

"Traceback (most recent call last):

  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 187, in Handle

    handler = _config_handle.add_wsgi_middleware(self._LoadHandler())

  File "/base/python27_runtime/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 225, in _LoadHandler

    handler = __import__(path[0])

  File "/base/data/home/apps/s~everyday-app/3.359804434352768230/application/__init__.py", line 21, in <module>

    import urls

  File "/base/data/home/apps/s~everyday-app/3.359804434352768230/application/urls.py", line 6, in <module>

    from application import app, views, util

ImportError: cannot import name views"

But then it stopped happening and is fine now. Was this an app engine issue where it didn't have all the files available for some reason? Or is this something that I need to be changing on my end?

My app runs on Python 2.7 with the Flask framework, and this is the first I've seen of this error.

Thanks!

[Takashi Matsuo]

Hi Pamela-

I have not heard any similar issues for now, and there was no outage
at that time period.
I found that the instance which had continuously threw that exception
initially encountered DeadlineExceededError.

Could you tell me how you're handling exceptions? There might be a
culprit that caused that instance got into the weird state.

-- Takashi

> --
> You received this message because you are subscribed to the Google Groups
> "Google App Engine" group.
> To post to this group, send email to google-a...@googlegroups.com.
> To unsubscribe from this group, send email to
> google-appengi...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/google-appengine?hl=en.



--
Takashi Matsuo | Developer Advocate | tma...@google.com

[Ian Lewis]

Pamela,

Specifically Takashi is probably asking if you have any naked except blocks:

try:
# Do something
except:
# Do a dance


People often do stuff like:

try:
import json
except:
import simplejson

If you have some of these, then you could be catching
DeadlineExceededErrors that occured
(they can occur basically anywhere on appengine). The instance should
get killed if one of
these errors occurs but it's best to handle it correctly in your code.

That kind of thing can cause problems. You need to do this instead.

try:
...
except Exception:
...

Some libraries are known to have these kinds of try except blocks.
Older versions of Jinja2 and werkzeug for example.

Ian

Ian

http://www.ianlewis.org/

[timh]

Yeah

This has been a problem at various stages with appengine and importing.  Depending on when/how you do imports

a DeadlineExceeded error can lead to problems importing stuff later.  For instance an import has a dependancy on a

failed import.

Once this happens (especially large stack apps - django, pyramid)  then you are hosed.

Are you using warmup requests.  By using them and doing all your imports in the warmup request and don't catch errors during import

means the instance won't get scheduled for service unless it starts up cleanly.

I have have code in place that also deals with import errors, by redirecting the user back to the page, and then consuming all memory so that the instance gets destroyed before it can service another request.  

Hope this helps

Rgds

Tim

>> To post to this group, send email to google-appengine@googlegroups.com.

>> To unsubscribe from this group, send email to

>> google-appengine+unsubscribe@googlegroups.com.

>> For more options, visit this group at
>> http://groups.google.com/group/google-appengine?hl=en.
>
>
>
> --
> Takashi Matsuo | Developer Advocate | tma...@google.com
>
> --
> You received this message because you are subscribed to the Google Groups "Google App Engine" group.

> To post to this group, send email to google-appengine@googlegroups.com.
> To unsubscribe from this group, send email to google-appengine+unsubscribe@googlegroups.com.