Queue.Queue uses a data structure that is shared between threads and locks/mutexes for correct behaviour.multiprocessing queues exchange data by pickling (serializing) objects and sending them through pipes.While the API looks similar (it's designed to be that way), the underlying mechanisms are fundamentally different. Unlike the standard library threading queue, the size of the queue is always known and can be returned by calling. If it is an integer greater than 0, then await put() blocks when the queue reaches maxsize until an item is removed by get(). The multiprocessing queues are for data interchange between different Python processes. If maxsize is less than or equal to zero, the queue size is infinite. Queue.Queue is made for data interchange between different threads inside the same process (using the threading module).

Setting the thread as a daemon thread will mean that the thread does not cause your program to stay running when the main thread finishes. while not q.empty(): sleep(1) If you dont set t.daemon True then the thread will never finish. Items placed in the Queue.Queue by the parent after starting the child will only be available to the parent. At the end of your main thread, you could add a simple empty check in a loop. Items placed in the Queue.Queue by the parent before starting the children will be available to each child. If the Queue.Queue is declared before the processes then each process will receive a copy of it which is then independent of every other process.

A Queue.Queue will not be shared between processes. For your second example, you already gave the explanation yourself- Queue is a module, which cannot be called.įor the third example: I assume that you use Queue.Queue together with multiprocessing.

Python queue module rocketmap