Revert "no need for task group here"

This reverts commit 876c682.

Author: sanderegg

packages/service-library/src/servicelib/redis/_semaphore_decorator.py

@@ -18,6 +18,7 @@
 )
 from ._errors import (
     SemaphoreAcquisitionError,
+    SemaphoreLostError,
     SemaphoreNotAcquiredError,
 )
 from ._semaphore import DistributedSemaphore
@@ -42,26 +43,42 @@ async def _managed_semaphore_execution(
         raise SemaphoreAcquisitionError(name=semaphore_key, capacity=semaphore.capacity)
 
     try:
-        started_event = asyncio.Event()
-
-        # Create auto-renewal task
-        @periodic(interval=ttl / 3, raise_on_error=True)
-        async def _periodic_renewer() -> None:
-            await semaphore.reacquire()
-            if not started_event.is_set():
-                started_event.set()
-
-        renewal_task = asyncio.create_task(
-            _periodic_renewer(),
-            name=f"semaphore/autorenewal_{semaphore_key}_{semaphore.instance_id}",
-        )
-        # Wait for first renewal to complete (ensures task is running)
-        await started_event.wait()
+        # Use TaskGroup for proper exception propagation
+        async with asyncio.TaskGroup() as tg:
+            started_event = asyncio.Event()
+
+            # Create auto-renewal task
+            @periodic(interval=ttl / 3, raise_on_error=True)
+            async def _periodic_renewer() -> None:
+                await semaphore.reacquire()
+                if not started_event.is_set():
+                    started_event.set()
+
+            # Start the renewal task
+            renewal_task = tg.create_task(
+                _periodic_renewer(),
+                name=f"semaphore/autorenewal_{semaphore_key}_{semaphore.instance_id}",
+            )
+
+            # Wait for first renewal to complete (ensures task is running)
+            await started_event.wait()
+
+            # Yield control back to caller
+            yield
+
+            # Cancel renewal task when execution is done
+            await cancel_wait_task(renewal_task, max_delay=None)
 
-        yield
+    except BaseExceptionGroup as eg:
+        semaphore_lost_errors, other_errors = eg.split(SemaphoreLostError)
+        # If there are any other errors, re-raise them
+        if other_errors:
+            assert len(other_errors.exceptions) == 1  # nosec
+            raise other_errors.exceptions[0] from eg
 
-        # Cancel renewal task when execution is done
-        await cancel_wait_task(renewal_task, max_delay=None)
+        assert semaphore_lost_errors is not None  # nosec
+        assert len(semaphore_lost_errors.exceptions) == 1  # nosec
+        raise semaphore_lost_errors.exceptions[0] from eg
 
     finally:
         # Always attempt to release the semaphore