Is get_or_create() thread safe

Question

I have a Django model that can only be accessed using get_or_create(session=session), where session is a foreign key to another Django model.

Since I am

Answer 1

I was having this problem with a view that calls get_or_create.

I was using Gunicorn with multiple workers, so to test it I changed the number of workers to 1 and this made the problem disappeared.

The simplest solution I found was to lock the table for access. I used this decorator to do the lock per view (for PostgreSQL):

http://www.caktusgroup.com/blog/2009/05/26/explicit-table-locking-with-postgresql-and-django/

EDIT: I wrapped the lock statement in that decorator in a try/except to deal with DB engines with no support for it (SQLite while unit testing in my case):

try:
    cursor.execute('LOCK TABLE %s IN %s MODE' % (model._meta.db_table, lock))
except DatabaseError: 
    pass