Added an optional thread name parameter to start_blocking_portal() (#900)

Author: davidbrochart

docs/versionhistory.rst

@@ -3,6 +3,11 @@ Version history
 
 This library adheres to `Semantic Versioning 2.0 <http://semver.org/>`_.
 
+**UNRELEASED**
+
+- Added the ability to specify the thread name in ``start_blocking_portal()``
+  (`#818 <https://github.com/agronholm/anyio/issues/818>`_; PR by @davidbrochart)
+
 **4.9.0**
 
 - Added async support for temporary file handling

src/anyio/from_thread.py

@@ -10,7 +10,7 @@
 )
 from dataclasses import dataclass, field
 from inspect import isawaitable
-from threading import Lock, Thread, get_ident
+from threading import Lock, Thread, current_thread, get_ident
 from types import TracebackType
 from typing import (
     Any,
@@ -454,7 +454,10 @@ def __exit__(
 
 @contextmanager
 def start_blocking_portal(
-    backend: str = "asyncio", backend_options: dict[str, Any] | None = None
+    backend: str = "asyncio",
+    backend_options: dict[str, Any] | None = None,
+    *,
+    name: str | None = None,
 ) -> Generator[BlockingPortal, Any, None]:
     """
     Start a new event loop in a new thread and run a blocking portal in its main task.
@@ -463,6 +466,7 @@ def start_blocking_portal(
 
     :param backend: name of the backend
     :param backend_options: backend options
+    :param name: name of the thread
     :return: a context manager that yields a blocking portal
 
     .. versionchanged:: 3.0
@@ -472,6 +476,9 @@ def start_blocking_portal(
 
     async def run_portal() -> None:
         async with BlockingPortal() as portal_:
+            if name is None:
+                current_thread().name = f"{backend}-portal-{id(portal_):x}"
+
             future.set_result(portal_)
             await portal_.sleep_until_stopped()
 
@@ -486,7 +493,7 @@ def run_blocking_portal() -> None:
                     future.set_exception(exc)
 
     future: Future[BlockingPortal] = Future()
-    thread = Thread(target=run_blocking_portal, daemon=True)
+    thread = Thread(target=run_blocking_portal, daemon=True, name=name)
     thread.start()
     try:
         cancel_remaining_tasks = False

tests/test_from_thread.py

@@ -371,6 +371,22 @@ async def async_get_thread_id() -> int:
         assert isinstance(thread_id, int)
         assert thread_id != threading.get_ident()
 
+    def test_start_with_thread_name(
+        self, anyio_backend_name: str, anyio_backend_options: dict[str, Any]
+    ) -> None:
+        with start_blocking_portal(
+            anyio_backend_name, anyio_backend_options, name="foo"
+        ) as portal:
+            assert portal.call(lambda: threading.current_thread().name) == "foo"
+
+    def test_start_without_thread_name(
+        self, anyio_backend_name: str, anyio_backend_options: dict[str, Any]
+    ) -> None:
+        with start_blocking_portal(anyio_backend_name, anyio_backend_options) as portal:
+            assert portal.call(lambda: threading.current_thread().name) == (
+                f"{anyio_backend_name}-portal-{id(portal):x}"
+            )
+
     def test_start_with_nonexistent_backend(self) -> None:
         with pytest.raises(LookupError) as exc:
             with start_blocking_portal("foo"):