Are Python instance variables thread-safe?

Question

OK, check following codes first:

class DemoClass():

    def __init__(self):
        #### I really want to know if self.Counter is thread-safe. 
        self         


        

Answer 1

No, it is not thread safe - the two threads are essentially modifying the same variable simultaneously. And yes, the solution is one of the locking mechanisms in the threading module.

BTW, self.Counter is an instance variable, not a class variable.