fix missing sleep to properly poll inside activity

polling/frequent/activities.py

@@ -1,3 +1,5 @@
+import asyncio
+import time
 from dataclasses import dataclass
 
 from temporalio import activity
@@ -17,6 +19,17 @@ async def compose_greeting(input: ComposeGreetingInput) -> str:
     while True:
         try:
             result = test_service.get_service_result(input)
+            activity.logger.info(f"Exiting activity ${result}")
             return result
-        except Exception:
+        except Exception as e:
+            # swallow exception since service is down
+            activity.logger.error(e)
+
+        try:
             activity.heartbeat("Invoking activity")
+        except asyncio.CancelledError as exception:
+            # activity was either cancelled or workflow was completed or worker shut down
+            # if you need to clean up you can catch this. Here we are just reraising exception
+            raise
+
+        await asyncio.sleep(1)