Python Django Global Variables

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Why one mustn’t declare global variables? O_o. It just looks like a propaganda. If the author knows what he wants and what side-effects will be, why not. Maybe it’s just a quick experiment.

You could declare your counter as a model class-member. Then to deal with race condition you have to add a method that will wait if some other client, from another thread works with counter. Something like this:

import threading

class MyModel(ModelBase):
    _counter = 0
    _counter_lock = threading.Lock()

    @classmethod
    def increment_counter(cls):
        with cls._counter_lock:
            cls._counter += 1

    def some_action(self):
        # core code
        self.increment_counter()


# somewhere else
print MyModel._counter

Remember however: you have to have your application in one process. So if you’ve deployed the application under Apache, be sure it is configured to spawn many threads, but not many processes. If you’re experimenting with ./manage.py run no actions are required.

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