Force commit of nested save() within a transaction
No, both your main saves and the status bar updates will be conducted using the same database connection so they will be part of the same transaction.
I can see two options to avoid this.

You can either create your own, separate database connection and save the status bar updates using that. 
Don't save the status bar updates to the database at all and instead use a cache to store them. As long as you don't use the database cache backend (ideally you'd use memcached) this will work fine.

My preferred option would be the second one. You'll need to delve into the Django internals to get your own database connection so that could is likely to end up fragile and messy.
I have a function where I save a large number of models, (thousands at a time), this takes several minutes so I have written a progress bar to display progress to the user. The progress bar works by polling a URL (from Javascript) and looking a request.session value to see the state of the first call (the one that is saving).
The problem is that the first call is within a @transaction.commit_on_success decorator and because I am using Database Backed sessions when I try to force request.session.save() instead of it immediately committing it is appended to the ongoing transaction. This results in the progress bar only being updated once all the saves are complete, thus rendering it useless.
My question is, (and I'm 99.99% sure I already know the answer), can you commit statements within a transaction without doing the whole lot. i.e. I need to just commit the request.session.save() whilst leaving all of the others..
Many thanks, Alex