multiprocessing: queue.get() blocks even if queue.qsize() != 0

[redbaron]

I run into problem with queue from multiprocessing. Even if I
queue.qsize() != 0 queue.get() still blocks and queue.get_nowait()
raises Emtpy error.

I'm unable to cut my big part to small test case, because smaller test
case similair to my real app by design is works. In what conditions is
it possible?

while qresult.qsize():
    result = qresult.get()  #this code blocks!
    doWithResult(result)