Are Python instance variables thread-safe?

Question

Check following codes first:

class DemoClass():

    def __init__(self):

        #### I really want to know if self.Counter is thread-safe. 

        self.Counter = 0

    def Increase(self):

        self.Counter = self.Counter + 1

    def Decrease(self):

        self.Counter = self.Counter - 1

    def DoThis(self):

        while True:

            Do something

            if A happens:

                self.Increase()

            else:

                self.Decrease()

            time.sleep(randomSecs)

    def DoThat(self):

        while True:

            Do other things

            if B happens:

                self.Increase()

            else:

                self.Decrease()

            time.sleep(randomSecs)

    def ThreadSafeOrNot(self):

        InterestingThreadA = threading.Thread(target = self.DoThis, args = ())

        InterestingThreadA.start()

        InterestingThreadB = threading.Thread(target = self.DoThat, args = ())

        InterestingThreadB.start()

I'm facing the same situation as above. I really want to know if it's thread-safe for self.Counter, well if not, what options do I have? I can only think of threading.RLock() to lock this resource, any better idea?

Answer 1

What you can do basically is to use the following artifacts: 

• Locks
• RLocks
• Semaphores
• Conditions
• Events 
• Queues

Go ahead and check this blog out, it contains the as it is information that you seek: Laurent Luce's Blog