Handling Simultaneous Session Updates

Question

In my django app, I have one AJAX view that gets flooded with calls to an update method, which I'll call IncrementMagicNumber:

def IncrementMagicNumber(request) :
   number = request.GET['increment']
   request.session['magicnumber'] = request.session['magicnumber'] + int(number)
   return HttpResponse("OK!")

This works fine for one update at a time, but when a client is calling SetMagicNumber several times in a row, things get messy. Let's say magicnumber is initially 0. The client sends out 3 successive AJAX requests to IncrementMagicNumber:

IncrementMagicNumber(2)
IncrementMagicNumber(5)
IncrementMagicNumber(4)

The client expects the value to be 11 now, but apache is processing all these requests concurrently, so only the final update gets retained. Any tips/tricks for synchronizing a Django session?

Things I'd like to avoid if at all possible:
- Client side batching (I realize this would fix it, but this is a backend problem and is best fixed there)
- Some sort of database locking; I'd rather avoid this approach if possible.

Answer 1

we do something like this and use database row locking. why do you want to avoid that? I'd say some kind of locking mechanism was required here.