Atomic block behaviour about django-sequences HOT 2 CLOSED

If two threads run this code concurrently, thread 2 will block on the get_next_value call and won't start executing # Code B until thread 1 finishes executing # Code C.

This is fairly easy to test by replacing # Code X with print("enter X"); time.sleep(10); print("exit X") and running the script in two terminals side by side.

If you try it, I'm interested in a confirmation that the behavior is indeed what I predicted.

PS - if you enabled the ATOMIC_REQUESTS option (which you probably did if you care enough about transactions to look at django-sequences) then the outer atomic block is created by Django and wraps the entire view.

from django-sequences.

Thanks for the reply. I can confirm your elaboration. I tested it "manually" using debugger and indeed, thread 2 would block until Code C is fully executed. It works like nesting atomic blocks.

And as to your PS - I did not enable ATOMIC_REQUESTS, and did it deliberately. I do not want requests to be atomic. This is actually the only case I need locking and syncing between requests. I do not want to loose performance :]

Thanks again for the clarification!

from django-sequences.