Catch RuntimeError in finalization of start_blocking_portal() (agronh…

…olm#472)

Fixes agronholm#471.

docs/versionhistory.rst

@@ -35,6 +35,9 @@ This library adheres to `Semantic Versioning 2.0 <http:https://semver.org/>`_.
  ``signal.Signals`` instances on the ``trio`` backend
 - Fixed ``to_thread.run_sync()`` hanging on asyncio if the target callable raises
  ``StopIteration``
+- Fixed ``start_blocking_portal()`` raising an unwarranted
+ ``RuntimeError: This portal is not running`` if a task raises an exception that causes
+ the event loop to be closed
 
 **3.6.1**
 

src/anyio/from_thread.py

@@ -406,12 +406,16 @@ async def run_portal() -> None:
 
  if future.done():
  portal = future.result()
+ cancel_remaining_tasks = False
  try:
  yield portal
  except BaseException:
- portal.call(portal.stop, True)
+ cancel_remaining_tasks = True
  raise
-
- portal.call(portal.stop, False)
+ finally:
+ try:
+ portal.call(portal.stop, cancel_remaining_tasks)
+ except RuntimeError:
+ pass
 
  run_future.result()

tests/test_from_thread.py

@@ -503,3 +503,24 @@ async def in_loop() -> None:
  await to_thread.run_sync(portal.start_task_soon, in_loop)
 
  assert not caplog.text
+
+ def test_raise_baseexception_from_task(
+ self, anyio_backend_name: str, anyio_backend_options: dict[str, Any]
+ ) -> None:
+ """
+ Test that when a task raises a BaseException, it does not trigger additional
+ exceptions when trying to close the portal.
+
+ """
+
+ async def raise_baseexception() -> None:
+ raise BaseException("fatal error")
+
+ with pytest.raises(BaseException, match="fatal error"):
+ with start_blocking_portal(
+ anyio_backend_name, anyio_backend_options
+ ) as portal:
+ with pytest.raises(BaseException, match="fatal error") as exc:
+ portal.call(raise_baseexception)
+
+ assert exc.value.__context__ is None