Pyramid app not releasing memory between views

Question

I've got a Pyramid view that's misbehaving in an interesting way. What the view does is grab a pretty complex object hierarchy from a file (using pickle), does a little processing, then renders an html form. Nice and simple.

Setup:

I'm running Ubuntu 12.04 64bit, Python3.2, Pyramid 1.3.3, SQLAlchemy 0.7.8 and using the standard waitress server.

Symptoms

I was having some efficiency issues so used system monitor to try to see what was up and found that while pyramid is doing its processing and suchlike for the view I described my ram usage rose steadily. As the html form was displayed in my browser the ram usage leveled off but didn't fall. Reloading the view caused the ram usage to grow steadily from where it left off. If I keep doing this all my ram is used up and everything grinds to a halt.

If I kill the server then the ram usage drops back down immediately.

Question

What's going on? It's obvious that memory isn't being released between view renderings, but why is this happening? And how can I make it stop? I even tried calling del on stuff before returning from the view and nothing changed.

Answer 1

Pyramid's debug toolbar keeps objects alive. Deactivating it fixes most memory leak problems. The leak that was the cause of my searching for errors in Pyramid doesn't seem to be a problem with Pyramid at all