Python threading and semaphore

Question

I have a python class let's call it AClass and another one MyThread which extends Thread. And in that AClass I make 2 objects of the class MyThread and I also have a semaphore which I give it as a parameter to the constructor of the MyThread class. My question is if I modify the semaphore in one MyThread object will the other MyThread object see the difference? Ex:

class AClasss:

     def function: 
          semafor = threading.Semaphore(value=maxconnections)
          thread1 = Mythread(semafor)
          thread2 = Mythread(semafor)
          thread1.start()
          thread1.join()
          thread2.start()
          thread2.join()

 class MyThread(Thread):
     def __init__(self,semaphore):
         self.semaphore = semaphore
     def run():
        semaphore.acquire()
        "Do something here" 
        semaphore.release()

So does thread1 see the changes to the semaphore that thread2 does and vice versa?

Answer 1

That's the purpose of semaphores, they allow you to safely synchronize concurrent processes.

Keep in mind that threads in Python won't really get you concurrency unless you're releasing the GIL (doing IO, calling libraries and so on). If that's what you're going for, you might want to consider the multiprocessing library.