Merge pull request #179 from pipermerriam/piper/ensure-asyncio-Endpoi…

…nt.stream-implementation-yields-to-event-loop

Ensure asyncio Endpoint.stream implementation yields to event loop

lahja/asyncio/endpoint.py

@@ -1,5 +1,5 @@
 import asyncio
-from asyncio import StreamReader, StreamWriter
+from asyncio import QueueEmpty, StreamReader, StreamWriter
 from collections import defaultdict
 import functools
 import itertools
@@ -756,7 +756,15 @@ async def stream(
         try:
             for _ in iterations:
                 try:
-                    yield await queue.get()
+                    try:
+                        yield queue.get_nowait()
+                    except QueueEmpty:
+                        yield await queue.get()
+                    else:
+                        # We sleep here to yield to the event loop in the case
+                        # that we were able to get an item from the queue
+                        # without an actual `await`
+                        await asyncio.sleep(0)
                 except GeneratorExit:
                     break
         finally:

newsfragments/179.bugfix.rst

@@ -0,0 +1 @@
+Ensure that the ``asyncio`` implementation releases control of the event loop on each iteration of the async iterator produced by `EndpointAPI.stream`