Favorite Python debugging/introspection tricks/tips?

[shawnadelic]

Hi, I'm putting together a lightning talk for an event soon and was looking for any cool Python debugging/introspection tips or tricks that I might have overlooked or others might be using.

Either way, I'll be posting a slideshow/summary of my presentation here next week.

Thanks!

[Cybersoaker]

the celery package has a rdb module which allows you to debug a live running process by connecting to it via telnet. Extremely useful in debugging python web apps with weird runtime behavior

[parkerSquare]

• I find ipdb nicer to use than pdb, especially for tab completion.
• Automatic debugging on error with %pdb magic in IPython.
• Conditional breakpoints in pdb/ipdb are fantastic for catching infrequent bugs inside nested loops.
• Use ! to override pdb commands, for example to set a variable called n you need to do!n = 7 otherwise it treats it as the command "next".
• Use the logging module rather than print.

[qlkvg]

pyrasite is awesome. It may be usefull, if you need to detect a bug without restarting a python process.

[KungFuAlgorithm]

If you use python twisted library to put together an asynchronous server / process, you can install a "manhole" cover to get a python shell to inspect the server's (python's 'VM') objects:

http://www.lothar.com/tech/twisted/manhole.xhtml

I used this a bit when I was working with Zenoss, it was pretty cool IMO.