AssertionError without traceback?

[Israel Brewster]

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Israel Brewster
Systems Analyst II
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
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[cid:bfa5c323-b100-481d-96b1-fc256ef2eb39 at flyravn.com]



[cid:8c891973-9e67-47b3-aa14-5f58b9b93607 at flyravn.com]







On Jan 14, 2019, at 10:40 PM, dieter <dieter at handshake.de<mailto:dieter at handshake.de>> wrote:

Israel Brewster <ibrewster at flyravn.com<mailto:ibrewster at flyravn.com>> writes:
I have a flask application deployed on CentOS 7 using Python 3.6.7 and uwsgi 2.0.17.1, proxied behind nginx. uwsgi is configured to listed on a socket in /tmp. The app uses gevent and the flask_uwsgi_websockets plugin as well as various other third-party modules, all installed via pip in a virtualenv. The environment was set up using pip just a couple of days ago, so everything should be fully up-to-date. The application *appears* to be running properly (it is in moderate use and there have been no reports of issues, nor has my testing turned up any problems), however I keep getting entries like the following in the error log:

AssertionError
2019-01-14T19:16:32Z <callback at 0x7f9bd4b2ae88 stopped> failed with AssertionError

I would try to find out where the log message above has been generated
and ensure it does not only log the information above but also the
associated traceback.

Any tips as to how? I tried putting in additional logging at a couple places where I called gevent.spawn() to see if that additional logging lined up with the assertions, but no luck. I guess I could just start peppering my code with logging commands, and hope something pops, but this seems quite...inelegant. I have not been able to reproduce the error, unfortunately.


I assume that the log comes from some framework -- maybe "uwsgi"
or "gevent". It is a weakness to log exceptions without the
associated traceback.


Fully agreed on both points. The reference to the callback for some reason puts me in mind of C code, but of course AssertionError is python, so maybe not.

For what it's worth, the issue only seems to happen when the server is under relatively heavy load. During the night, when it is mostly idle, I don't get many (if any) errors. And this has only been happening since I upgraded to CentOS7 and the latest versions of all the frameworks. Hopefully it isn't a version incompatibility...

There is no additional information provided, just that. I was running the same app (checked out from a GIT repository, so exact same code) on CentOS 6 for years without issue, it was only since I moved to CentOS 7 that I've seen the errors. I have not so far been able to correlate this error with any specific request. Has anyone seen anything like this before such that you can give me some pointers to fixing this? As the application *appears* to be functioning normally, it may not be a big issue, but it has locked up once since the move (no errors in the log, just not responding on the socket), so I am a bit concerned.
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Israel Brewster
Systems Analyst II
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7293
-----------------------------------------------

[cid:05a3a602-0c27-4749-91b8-096a5857d984 at flyravn.com]



[cid:bbc82752-6db4-44cf-b919-421ed304e1d1 at flyravn.com]

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