I don't understand what is happening in this threading code

[Matthew Wilson]

In this code, I tried to kill my thread object by setting a variable on it
to False.

Inside the run method of my thread object, it checks a different
variable.

I've already rewritten this code to use semaphores, but I'm just curious
what is going on.

Here's the code:

import logging, threading, time
logging.basicConfig(level=logging.DEBUG,
                    format="%(threadName)s: %(message)s")

class Waiter(threading.Thread):
    def __init__(self, hot_food):
        super(Waiter, self).__init__()
        self.should_keep_running = True
        self.hot_food = hot_food

    def run(self):
        while self.should_keep_running:
            logging.debug("Inside run, the id of should_keep_running is %s." 
                          % id(self.should_keep_running))
            self.hot_food.acquire()

def cook_food(hot_food):
    i = 5
    while i >= 0: 
        logging.debug("I am cooking food...")
        time.sleep(1)
        hot_food.release()
        logging.debug("Andiamo!")
        i -= 1

def main():

    hot_food = threading.Semaphore(value=0)

    chef = threading.Thread(name="chef", target=cook_food, args=(hot_food, ))
    chef.start()
            
    w = Waiter(hot_food)
    logging.debug("Initially, the id of w.should_keep_running is %s." 
              % id(w.should_keep_running))
    w.start()
    logging.debug("After start, the id of w.should_keep_running is %s." 
              % id(w.should_keep_running))

    # Wait for the chef to finish work.
    chef.join()

    # Now try to kill off the waiter by setting a variable inside the waiter.
    w.should_keep_running = False
    logging.debug("Now, the id of w.should_keep_running is %s."     
                  % id(w.should_keep_running))

if __name__ == "__main__":
    main()

And here's what I get when I execute it.  I have to suspend the process
with CTRL=Z and then kill -9 it.

$ python foo.py
MainThread: Initially, the id of w.should_keep_running is 135527852.
MainThread: After start, the id of w.should_keep_running is 135527852.
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
chef: I am cooking food...
Thread-1: Inside run, the id of should_keep_running is 135527852.
chef: Andiamo!
Thread-1: Inside run, the id of should_keep_running is 135527852.
MainThread: Now, the id of w.should_keep_running is 135527840.

[1]+  Stopped                 python foo.py

$ kill -9 %1

[1]+  Stopped                 python foo.py

The memory address of should_keep_running seems to change when I set it
from True to False, and inside the run method, I keep checking the old
location.

I am totally baffled what this means.

Like I said earlier, I already rewrote this code to use semaphores, but
I just want to know what is going on here.

Any explanation is welcome.

TIA

Matt