Why do we need gevent.queue?

Question

My understanding of Gevent is that it's merely concurrency and not parallelism. My understanding of concurrency mechanisms like Gevent and AsyncIO is that, nothing in the Python application is ever executing at the same time.

The closest you get is, calling a non-blocking IO method, and while waiting for that call to return other methods within the Python application are able to be executed. Again, none of the methods within the Python application ever actually execute Python code at the same time.

With that said, why is there a need for gevent.queue? It sounds to me like the Python application doesn't really need to worry about more than one Python method accessing a queue instance at a time.

I'm sure there's a scenario that I'm not seeing that gevent.queue fixes, I'm just curious what that is.

Answer 1

Although you are right that no two statements execute at the same time within a single Python process, you might want to ensure that a series of statements execute atomically, or you might want to impose an order on the execution of certain statements, and in that case things like gevent.queue become useful. A tutorial is here.