Fallback to event loop import on deadlock (#111868)

homeassistant/loader.py

@@ -852,7 +852,14 @@ class Integration:
         # Some integrations fail on import because they call functions incorrectly.
         # So we do it before validating config to catch these errors.
         if load_executor:
-            comp = await self.hass.async_add_executor_job(self.get_component)
+            try:
+                comp = await self.hass.async_add_executor_job(self.get_component)
+            except ImportError as ex:
+                load_executor = False
+                _LOGGER.debug("Failed to import %s in executor", domain, exc_info=ex)
+                # If importing in the executor deadlocks because there is a circular
+                # dependency, we fall back to the event loop.
+                comp = self.get_component()
         else:
             comp = self.get_component()
 
@@ -885,6 +892,9 @@ class Integration:
             )
         except ImportError:
             raise
+        except RuntimeError as err:
+            # _DeadlockError inherits from RuntimeError
+            raise ImportError(f"RuntimeError importing {self.pkg_path}: {err}") from err
         except Exception as err:
             _LOGGER.exception(
                 "Unexpected exception importing component %s", self.pkg_path
@@ -913,9 +923,18 @@ class Integration:
         )
         try:
             if load_executor:
-                platform = await self.hass.async_add_executor_job(
-                    self._load_platform, platform_name
-                )
+                try:
+                    platform = await self.hass.async_add_executor_job(
+                        self._load_platform, platform_name
+                    )
+                except ImportError as ex:
+                    _LOGGER.debug(
+                        "Failed to import %s in executor", domain, exc_info=ex
+                    )
+                    load_executor = False
+                    # If importing in the executor deadlocks because there is a circular
+                    # dependency, we fall back to the event loop.
+                    platform = self._load_platform(platform_name)
             else:
                 platform = self._load_platform(platform_name)
             import_future.set_result(platform)
@@ -983,6 +1002,11 @@ class Integration:
                 ]
                 missing_platforms_cache[full_name] = ex
             raise
+        except RuntimeError as err:
+            # _DeadlockError inherits from RuntimeError
+            raise ImportError(
+                f"RuntimeError importing {self.pkg_path}.{platform_name}: {err}"
+            ) from err
         except Exception as err:
             _LOGGER.exception(
                 "Unexpected exception importing platform %s.%s",

tests/test_loader.py

@@ -1,6 +1,8 @@
 """Test to verify that we can load components."""
 import asyncio
-from unittest.mock import Mock, patch
+import sys
+from typing import Any
+from unittest.mock import MagicMock, Mock, patch
 
 import pytest
 
@@ -1033,3 +1035,161 @@ async def test_hass_components_use_reported(
             "Detected that custom integration 'test_integration_frame'"
             " accesses hass.components.http. This is deprecated"
         ) in caplog.text
+
+
+async def test_async_get_component_deadlock_fallback(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Verify async_get_component fallback to importing in the event loop on deadlock."""
+    executor_import_integration = _get_test_integration(
+        hass, "executor_import", True, import_executor=True
+    )
+    assert executor_import_integration.import_executor is True
+    module_mock = MagicMock()
+    import_attempts = 0
+
+    def mock_import(module: str, *args: Any, **kwargs: Any) -> Any:
+        nonlocal import_attempts
+        if module == "homeassistant.components.executor_import":
+            import_attempts += 1
+
+        if import_attempts == 1:
+            # _DeadlockError inherits from RuntimeError
+            raise RuntimeError(
+                "Detected deadlock trying to import homeassistant.components.executor_import"
+            )
+
+        return module_mock
+
+    assert "homeassistant.components.executor_import" not in sys.modules
+    assert "custom_components.executor_import" not in sys.modules
+    with patch("homeassistant.loader.importlib.import_module", mock_import):
+        module = await executor_import_integration.async_get_component()
+
+    assert (
+        "Detected deadlock trying to import homeassistant.components.executor_import"
+        in caplog.text
+    )
+    assert "loaded_executor=False" in caplog.text
+    assert module is module_mock
+
+
+async def test_async_get_component_raises_after_import_failure(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Verify async_get_component raises if we fail to import in both the executor and loop."""
+    executor_import_integration = _get_test_integration(
+        hass, "executor_import", True, import_executor=True
+    )
+    assert executor_import_integration.import_executor is True
+    module_mock = MagicMock()
+    import_attempts = 0
+
+    def mock_import(module: str, *args: Any, **kwargs: Any) -> Any:
+        nonlocal import_attempts
+        if module == "homeassistant.components.executor_import":
+            import_attempts += 1
+
+        if import_attempts == 1:
+            # _DeadlockError inherits from RuntimeError
+            raise RuntimeError(
+                "Detected deadlock trying to import homeassistant.components.executor_import"
+            )
+
+        if import_attempts == 2:
+            raise ImportError("Failed import homeassistant.components.executor_import")
+        return module_mock
+
+    assert "homeassistant.components.executor_import" not in sys.modules
+    assert "custom_components.executor_import" not in sys.modules
+    with patch(
+        "homeassistant.loader.importlib.import_module", mock_import
+    ), pytest.raises(ImportError):
+        await executor_import_integration.async_get_component()
+
+    assert (
+        "Detected deadlock trying to import homeassistant.components.executor_import"
+        in caplog.text
+    )
+    assert "loaded_executor=False" not in caplog.text
+
+
+async def test_async_get_platform_deadlock_fallback(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Verify async_get_platform fallback to importing in the event loop on deadlock."""
+    executor_import_integration = _get_test_integration(
+        hass, "executor_import", True, import_executor=True
+    )
+    assert executor_import_integration.import_executor is True
+    module_mock = MagicMock()
+    import_attempts = 0
+
+    def mock_import(module: str, *args: Any, **kwargs: Any) -> Any:
+        nonlocal import_attempts
+        if module == "homeassistant.components.executor_import.config_flow":
+            import_attempts += 1
+
+        if import_attempts == 1:
+            # _DeadlockError inherits from RuntimeError
+            raise RuntimeError(
+                "Detected deadlock trying to import homeassistant.components.executor_import"
+            )
+
+        return module_mock
+
+    assert "homeassistant.components.executor_import" not in sys.modules
+    assert "custom_components.executor_import" not in sys.modules
+    with patch("homeassistant.loader.importlib.import_module", mock_import):
+        module = await executor_import_integration.async_get_platform("config_flow")
+
+    assert (
+        "Detected deadlock trying to import homeassistant.components.executor_import"
+        in caplog.text
+    )
+    assert "loaded_executor=False" in caplog.text
+    assert module is module_mock
+
+
+async def test_async_get_platform_raises_after_import_failure(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Verify async_get_platform raises if we fail to import in both the executor and loop."""
+    executor_import_integration = _get_test_integration(
+        hass, "executor_import", True, import_executor=True
+    )
+    assert executor_import_integration.import_executor is True
+    module_mock = MagicMock()
+    import_attempts = 0
+
+    def mock_import(module: str, *args: Any, **kwargs: Any) -> Any:
+        nonlocal import_attempts
+        if module == "homeassistant.components.executor_import.config_flow":
+            import_attempts += 1
+
+        if import_attempts == 1:
+            # _DeadlockError inherits from RuntimeError
+            raise RuntimeError(
+                "Detected deadlock trying to import homeassistant.components.executor_import"
+            )
+
+        if import_attempts == 2:
+            # _DeadlockError inherits from RuntimeError
+            raise ImportError(
+                "Error trying to import homeassistant.components.executor_import"
+            )
+
+        return module_mock
+
+    assert "homeassistant.components.executor_import" not in sys.modules
+    assert "custom_components.executor_import" not in sys.modules
+    with patch(
+        "homeassistant.loader.importlib.import_module", mock_import
+    ), pytest.raises(ImportError):
+        await executor_import_integration.async_get_platform("config_flow")
+
+    assert (
+        "Detected deadlock trying to import homeassistant.components.executor_import"
+        in caplog.text
+    )
+    assert "loaded_executor=False" not in caplog.text