[Django]-Static methods and thread safety

Functions in a module are equivalent to static methods in a class. The issue of thread safety arises when multiple threads may be modifying shared data, or even one thread may be modifying such data while others are reading it; it’s best avoided by making data be owned by ONE module (accessed via Queue.Queue from others), but when that’s not feasible you have to resort to locking and other, more complex, synchronization primitives.

This applies whether the access to shared data happens in module functions, static methods, or instance methods — and the shared data is such whether it’s instance variables, class ones, or global ones (scoping and thread safety are essentially disjoint, except that function-local data is, to a pont, intrinsically thread-safe — no other thread will ever see the data inside a function instance, until and unless the function deliberately “shares” it through shared containers).

If you use the multiprocessing module in Python’s standard library, instead of the threading module, you may in fact not have to care about “thread safety” — essentially because NO data is shared among processes… well, unless you go out of your way to change that, e.g. via mmapped files;-).

See the python documentation to better understand the general thread safety implications of Python.

Django itself seems to be thread safe as of 1.0.3, but your code may not and you will have to verify that…

My advice would be to simply don’t care about that and serve your application with multiple processes instead of multiple threads (for example by using apache ‘prefork’ instead of ‘worker’ MPM).