Truncated or oversized response headers received from daemon process

Question

I recently migrated a python django application from a debian system to a redhat enterprise distribution. The application is hosted using httpd, mod_wsgi and running in a venv in an daemon process. On large requests I now get following error message in the log file:

"Truncated or oversized response headers received from daemon process" 

I have never experienced anything like this and Google is not the key here as well. I checked configuration of apache, but no config is related to response headers in there.

My httpd.conf configuration looks like this ( pretty standard):

WSGIPassAuthorization On
WSGIScriptAlias / /var/www/myapp/wsgi.py
WSGIDaemonProcess my.name python-path=/path/to/myapp/:/path/to/venv/lib/python2.7/site-packages display-name=%{GROUP}
WSGIProcessGroup my.name

Does any Guru have a hint in which direction I should look?

Answer 1

We recently ran into this issue, and after days of vigorous ugoogleizing and massive headache, we discovered that we were using psycopg2-binary as our database connector dependency (I know, newbs)! It states right in their documentation not to use the package in a production environment.

We did add all the other proposed answers such as adding 'WSGIApplicationGroup %{GLOBAL}' to our settings (which we kept), but all of them alone and together didn't solve the issue.

We also found that other C libraries like numpy, cause issues.

Hope this helps someone some day.

Django Webfaction 'Timeout when reading response headers from daemon process'

http://initd.org/psycopg/docs/install.html#prerequisites

Answer 2

Turned out to be not the actual problem. The problem was lying deeper, as I changed Cairo to CairoCffi and the RSVG-Handler couldn't deal with the Context-Object coming from Cffi. No my actuall problem is having an up-to-date python lib that allows me to convert svg into png. Using svg2png from CairoSVG isn't working for me. I get an

cairo returned CAIRO_STATUS_NO_MEMORY: out of memory

Error, which I'm sure of, that it does not tell the truth again and the problem lies somewhere else. But lets see.