fix: Re-raise python asyncio.CancelledErrors (#31982)
This is motivated by #31227 which I also encountered recently. I'm not familiar with the call lifecycle details, but it seems clear that there is some kind of race condition between user-initiated cancellations and other completion status updates.
If a user cancels a call before being notified of its completion, I believe it should be considered cancelled unconditionally, regardless of whether the call actually completed successfully before its cancellation status could be set.
So it seems better to re-raise explicitly rather than using self._raise_for_status(), which is a no-op in this race condition and can lead to an UnboundedLocalError.
diff --git a/src/python/grpcio/grpc/aio/_call.py b/src/python/grpcio/grpc/aio/_call.py
index 1644358..4af04eb 100644
--- a/src/python/grpcio/grpc/aio/_call.py
+++ b/src/python/grpcio/grpc/aio/_call.py
@@ -341,7 +341,7 @@
except asyncio.CancelledError:
if not self.cancelled():
self.cancel()
- await self._raise_for_status()
+ raise
if raw_response is cygrpc.EOF:
return cygrpc.EOF
@@ -449,7 +449,7 @@
except asyncio.CancelledError:
if not self.cancelled():
self.cancel()
- await self._raise_for_status()
+ raise
async def _done_writing(self) -> None:
if self.done():
@@ -463,7 +463,7 @@
except asyncio.CancelledError:
if not self.cancelled():
self.cancel()
- await self._raise_for_status()
+ raise
async def write(self, request: RequestType) -> None:
self._raise_for_different_style(_APIStyle.READER_WRITER)
@@ -602,6 +602,7 @@
except asyncio.CancelledError:
if not self.cancelled():
self.cancel()
+ raise
if self._cython_call.is_ok():
return _common.deserialize(serialized_response,
