Django stops printing to stdout

Question

Hi

First of all, I'm using Windows, just to make that clear. I am using cmd.exe to manage runserver and the server runs just fine. However, sometimes, on a seemingly random basis, Django simply stops writing to stdout! The server responds to my requests and everything, but nothing gets printed.

To make it even clearer, I'm not even talking about print in my Django code, so that cannot be the problem. I'm talking about when it prints e.g. GET /someurl HTTP/1.1, yada-yada... Hitting Ctrl+Break and restarting the server doesn't help. However, if I exit the command prompt and start a new one and run the server in that one, it starts working again.

Any ideas about what's going on? This is with Django 1.0.2 final and Python 2.6.2.

Answer 1

Do you assign something to sys.stdout or sys.stderr at some point in your code?

Answer 2

The development server can act weird sometimes, just stop it with ctrl-break then start it again.

One thing you can try, just to be sure that the server itself didn't stop, is do a hard-refresh (ctrl-F5), if it doesn't respond, then the server is actually dead, and you were just seeing the cached version of the page.

Answer 3

This may seem stupid, but did you check the log files? Also, you could make a lot of requests from urllib, or whatever web client you want, and try to reproduce that. Maybe you'll see a pattern as to why this happens.

Answer 4

Maybe a bit of a stretch,but under Python 2.6 under Linux using the Twisted framework (instead of Django), I had this behaviour occur anytime my application sent a NULL to stdout and stdout was redirected to syslog. I had assumed this was a bug in the twisted framework's syslog implementation, but maybe its something more. Can you tell from either logging or client activity what the last thing it was doing before losing stdout and see if it is a) always in one of a handful of places and 2) if you are sending anything funky out at the time?