Reconnect to GRPC when the sidecar restarts (#45)

Signed-off-by: Albert Callarisa <albert@diagrid.io>

Author: acroca

durabletask/worker.py

@@ -636,12 +636,15 @@ def stream_reader():
 
                 if self._shutdown.is_set():
                     self._logger.info(f"Disconnected from {self._host_address}")
-                else:
-                    self._logger.info("Work item stream ended normally")
-                # When stream ends (SHUTDOWN_SENTINEL received), always break outer loop
-                # The stream reader has exited, so we should exit too, not reconnect
-                # This matches Go SDK behavior where stream ending causes the listener to exit
-                break
+                    break
+
+                # Stream ended without shutdown being requested - reconnect
+                self._logger.info(
+                    f"Work item stream ended. Will attempt to reconnect to {self._host_address}..."
+                )
+                invalidate_connection()
+                # Fall through to the top of the outer loop, which will
+                # create a fresh connection (with retry/backoff if needed)
             except grpc.RpcError as rpc_error:
                 # Check shutdown first - if shutting down, exit immediately
                 if self._shutdown.is_set():
@@ -847,6 +850,13 @@ def _execute_orchestrator(
             stub.CompleteOrchestratorTask(res)
         except grpc.RpcError as rpc_error:  # type: ignore
             self._handle_grpc_execution_error(rpc_error, "orchestrator")
+        except ValueError:
+            # gRPC raises ValueError when the underlying channel has been closed (e.g. during reconnection).
+            self._logger.debug(
+                f"Could not deliver orchestrator response for '{req.instanceId}': "
+                f"channel was closed (likely due to reconnection). "
+                f"The sidecar will re-dispatch this work item."
+            )
         except Exception as ex:
             self._logger.exception(
                 f"Failed to deliver orchestrator response for '{req.instanceId}' to sidecar: {ex}"
@@ -897,6 +907,13 @@ def _execute_activity(
                 stub.CompleteActivityTask(res)
             except grpc.RpcError as rpc_error:  # type: ignore
                 self._handle_grpc_execution_error(rpc_error, "activity")
+            except ValueError:
+                # gRPC raises ValueError when the underlying channel has been closed (e.g. during reconnection).
+                self._logger.debug(
+                    f"Could not deliver activity response for '{req.name}#{req.taskId}' of "
+                    f"orchestration ID '{instance_id}': channel was closed (likely due to "
+                    f"reconnection). The sidecar will re-dispatch this work item."
+                )
             except Exception as ex:
                 self._logger.exception(
                     f"Failed to deliver activity response for '{req.name}#{req.taskId}' of orchestration ID '{instance_id}' to sidecar: {ex}"