Ah yes – sorry, I forgot to actually add logic to refresh the stream generator.
At any time in your loop, you can break – but you have to decide when the stream is actually "done". When you're sending out the new questions, you don't always know what answers were "lost" and what answers are still being answered. Maybe the annotator is just taking a while and still has the questions in the queue – in that case, you might not want to send them out again immediately.
A very basic solution would be to check the hashes of the incoming examples against the hashes already present in the current dataset and break if all hashes are covered. You might find this thread useful, which explains a lot of this in more detail and has some examples: