Turn on thread safety checks in async_dispatcher_send (#116867)

* Turn on thread safety checks in async_dispatcher_send

We keep seeing issues where async_dispatcher_send is called from
a thread which means we call the callback function on the other
side in the thread as well which usually leads to a crash

* Turn on thread safety checks in async_dispatcher_send

We keep seeing issues where async_dispatcher_send is called from
a thread which means we call the callback function on the other
side in the thread as well which usually leads to a crash

* adjust

homeassistant/bootstrap.py

@@ -84,7 +84,7 @@ from .helpers import (
     template,
     translation,
 )
-from .helpers.dispatcher import async_dispatcher_send
+from .helpers.dispatcher import async_dispatcher_send_internal
 from .helpers.storage import get_internal_store_manager
 from .helpers.system_info import async_get_system_info
 from .helpers.typing import ConfigType
@@ -700,7 +700,7 @@ class _WatchPendingSetups:
     def _async_dispatch(self, remaining_with_setup_started: dict[str, float]) -> None:
         """Dispatch the signal."""
         if remaining_with_setup_started or not self._previous_was_empty:
-            async_dispatcher_send(
+            async_dispatcher_send_internal(
                 self._hass, SIGNAL_BOOTSTRAP_INTEGRATIONS, remaining_with_setup_started
             )
         self._previous_was_empty = not remaining_with_setup_started

homeassistant/config_entries.py

@@ -48,7 +48,7 @@ from .exceptions import (
 )
 from .helpers import device_registry, entity_registry, issue_registry as ir, storage
 from .helpers.debounce import Debouncer
-from .helpers.dispatcher import SignalType, async_dispatcher_send
+from .helpers.dispatcher import SignalType, async_dispatcher_send_internal
 from .helpers.event import (
     RANDOM_MICROSECOND_MAX,
     RANDOM_MICROSECOND_MIN,
@@ -841,7 +841,7 @@ class ConfigEntry(Generic[_DataT]):
             error_reason_translation_placeholders,
         )
         self.clear_cache()
-        async_dispatcher_send(
+        async_dispatcher_send_internal(
             hass, SIGNAL_CONFIG_ENTRY_CHANGED, ConfigEntryChange.UPDATED, self
         )
 
@@ -1880,6 +1880,7 @@ class ConfigEntries:
         if entry.entry_id not in self._entries:
             raise UnknownEntry(entry.entry_id)
 
+        self.hass.verify_event_loop_thread("async_update_entry")
         changed = False
         _setter = object.__setattr__
 
@@ -1928,7 +1929,7 @@ class ConfigEntries:
         self, change_type: ConfigEntryChange, entry: ConfigEntry
     ) -> None:
         """Dispatch a config entry change."""
-        async_dispatcher_send(
+        async_dispatcher_send_internal(
             self.hass, SIGNAL_CONFIG_ENTRY_CHANGED, change_type, entry
         )
 

homeassistant/helpers/discovery.py

@@ -16,7 +16,7 @@ from homeassistant.const import Platform
 from homeassistant.loader import bind_hass
 
 from ..util.signal_type import SignalTypeFormat
-from .dispatcher import async_dispatcher_connect, async_dispatcher_send
+from .dispatcher import async_dispatcher_connect, async_dispatcher_send_internal
 from .typing import ConfigType, DiscoveryInfoType
 
 SIGNAL_PLATFORM_DISCOVERED: SignalTypeFormat[DiscoveryDict] = SignalTypeFormat(
@@ -95,7 +95,9 @@ async def async_discover(
         "discovered": discovered,
     }
 
-    async_dispatcher_send(hass, SIGNAL_PLATFORM_DISCOVERED.format(service), data)
+    async_dispatcher_send_internal(
+        hass, SIGNAL_PLATFORM_DISCOVERED.format(service), data
+    )
 
 
 @bind_hass
@@ -177,4 +179,6 @@ async def async_load_platform(
         "discovered": discovered,
     }
 
-    async_dispatcher_send(hass, SIGNAL_PLATFORM_DISCOVERED.format(service), data)
+    async_dispatcher_send_internal(
+        hass, SIGNAL_PLATFORM_DISCOVERED.format(service), data
+    )

homeassistant/helpers/dispatcher.py

@@ -145,7 +145,7 @@ def dispatcher_send(hass: HomeAssistant, signal: str, *args: Any) -> None: ...
 @bind_hass  # type: ignore[misc]  # workaround; exclude typing of 2 overload in func def
 def dispatcher_send(hass: HomeAssistant, signal: SignalType[*_Ts], *args: *_Ts) -> None:
     """Send signal and data."""
-    hass.loop.call_soon_threadsafe(async_dispatcher_send, hass, signal, *args)
+    hass.loop.call_soon_threadsafe(async_dispatcher_send_internal, hass, signal, *args)
 
 
 def _format_err(
@@ -199,9 +199,33 @@ def async_dispatcher_send(
 
     This method must be run in the event loop.
     """
-    if hass.config.debug:
+    # We turned on asyncio debug in April 2024 in the dev containers
+    # in the hope of catching some of the issues that have been
+    # reported. It will take a while to get all the issues fixed in
+    # custom components.
+    #
+    # In 2025.5 we should guard the `verify_event_loop_thread`
+    # check with a check for the `hass.config.debug` flag being set as
+    # long term we don't want to be checking this in production
+    # environments since it is a performance hit.
     hass.verify_event_loop_thread("async_dispatcher_send")
+    async_dispatcher_send_internal(hass, signal, *args)
 
+
+@callback
+@bind_hass
+def async_dispatcher_send_internal(
+    hass: HomeAssistant, signal: SignalType[*_Ts] | str, *args: *_Ts
+) -> None:
+    """Send signal and data.
+
+    This method is intended to only be used by core internally
+    and should not be considered a stable API. We will make
+    breaking changes to this function in the future and it
+    should not be used in integrations.
+
+    This method must be run in the event loop.
+    """
     if (maybe_dispatchers := hass.data.get(DATA_DISPATCHER)) is None:
         return
     dispatchers: _DispatcherDataType[*_Ts] = maybe_dispatchers

homeassistant/helpers/script.py

@@ -85,7 +85,7 @@ from homeassistant.util.signal_type import SignalType, SignalTypeFormat
 
 from . import condition, config_validation as cv, service, template
 from .condition import ConditionCheckerType, trace_condition_function
-from .dispatcher import async_dispatcher_connect, async_dispatcher_send
+from .dispatcher import async_dispatcher_connect, async_dispatcher_send_internal
 from .event import async_call_later, async_track_template
 from .script_variables import ScriptVariables
 from .trace import (
@@ -208,7 +208,9 @@ async def trace_action(
                 )
             )
         ):
-            async_dispatcher_send(hass, SCRIPT_BREAKPOINT_HIT, key, run_id, path)
+            async_dispatcher_send_internal(
+                hass, SCRIPT_BREAKPOINT_HIT, key, run_id, path
+            )
 
             done = hass.loop.create_future()
 
@@ -1986,7 +1988,7 @@ def debug_continue(hass: HomeAssistant, key: str, run_id: str) -> None:
     breakpoint_clear(hass, key, run_id, NODE_ANY)
 
     signal = SCRIPT_DEBUG_CONTINUE_STOP.format(key, run_id)
-    async_dispatcher_send(hass, signal, "continue")
+    async_dispatcher_send_internal(hass, signal, "continue")
 
 
 @callback
@@ -1996,11 +1998,11 @@ def debug_step(hass: HomeAssistant, key: str, run_id: str) -> None:
     breakpoint_set(hass, key, run_id, NODE_ANY)
 
     signal = SCRIPT_DEBUG_CONTINUE_STOP.format(key, run_id)
-    async_dispatcher_send(hass, signal, "continue")
+    async_dispatcher_send_internal(hass, signal, "continue")
 
 
 @callback
 def debug_stop(hass: HomeAssistant, key: str, run_id: str) -> None:
     """Stop execution of a running or halted script."""
     signal = SCRIPT_DEBUG_CONTINUE_STOP.format(key, run_id)
-    async_dispatcher_send(hass, signal, "stop")
+    async_dispatcher_send_internal(hass, signal, "stop")

tests/helpers/test_dispatcher.py

@@ -243,7 +243,6 @@ async def test_dispatcher_add_dispatcher(hass: HomeAssistant) -> None:
 
 async def test_thread_safety_checks(hass: HomeAssistant) -> None:
     """Test dispatcher thread safety checks."""
-    hass.config.debug = True
     calls = []
 
     @callback