Fix scheduler race conditions and add comprehensive test suite (#9348)

tests/integration/test_scheduler_defer_stress.py

@@ -0,0 +1,137 @@
+"""Stress test for defer() thread safety with multiple threads."""
+
+import asyncio
+from pathlib import Path
+import re
+
+from aioesphomeapi import UserService
+import pytest
+
+from .types import APIClientConnectedFactory, RunCompiledFunction
+
+
+@pytest.mark.asyncio
+async def test_scheduler_defer_stress(
+    yaml_config: str,
+    run_compiled: RunCompiledFunction,
+    api_client_connected: APIClientConnectedFactory,
+) -> None:
+    """Test that defer() doesn't crash when called rapidly from multiple threads."""
+
+    # Get the absolute path to the external components directory
+    external_components_path = str(
+        Path(__file__).parent / "fixtures" / "external_components"
+    )
+
+    # Replace the placeholder in the YAML config with the actual path
+    yaml_config = yaml_config.replace(
+        "EXTERNAL_COMPONENT_PATH", external_components_path
+    )
+
+    # Create a future to signal test completion
+    loop = asyncio.get_event_loop()
+    test_complete_future: asyncio.Future[None] = loop.create_future()
+
+    # Track executed defers and their order
+    executed_defers: set[int] = set()
+    thread_executions: dict[
+        int, list[int]
+    ] = {}  # thread_id -> list of indices in execution order
+    fifo_violations: list[str] = []
+
+    def on_log_line(line: str) -> None:
+        # Track all executed defers with thread and index info
+        match = re.search(r"Executed defer (\d+) \(thread (\d+), index (\d+)\)", line)
+        if not match:
+            return
+
+        defer_id = int(match.group(1))
+        thread_id = int(match.group(2))
+        index = int(match.group(3))
+
+        executed_defers.add(defer_id)
+
+        # Track execution order per thread
+        if thread_id not in thread_executions:
+            thread_executions[thread_id] = []
+
+        # Check FIFO ordering within thread
+        if thread_executions[thread_id] and thread_executions[thread_id][-1] >= index:
+            fifo_violations.append(
+                f"Thread {thread_id}: index {index} executed after "
+                f"{thread_executions[thread_id][-1]}"
+            )
+
+        thread_executions[thread_id].append(index)
+
+        # Check if we've executed all 1000 defers (0-999)
+        if len(executed_defers) == 1000 and not test_complete_future.done():
+            test_complete_future.set_result(None)
+
+    async with (
+        run_compiled(yaml_config, line_callback=on_log_line),
+        api_client_connected() as client,
+    ):
+        # Verify we can connect
+        device_info = await client.device_info()
+        assert device_info is not None
+        assert device_info.name == "scheduler-defer-stress-test"
+
+        # List entities and services
+        entity_info, services = await asyncio.wait_for(
+            client.list_entities_services(), timeout=5.0
+        )
+
+        # Find our test service
+        run_stress_test_service: UserService | None = None
+        for service in services:
+            if service.name == "run_stress_test":
+                run_stress_test_service = service
+                break
+
+        assert run_stress_test_service is not None, "run_stress_test service not found"
+
+        # Call the run_stress_test service to start the test
+        client.execute_service(run_stress_test_service, {})
+
+        # Wait for all defers to execute (should be quick)
+        try:
+            await asyncio.wait_for(test_complete_future, timeout=5.0)
+        except asyncio.TimeoutError:
+            # Report how many we got
+            pytest.fail(
+                f"Stress test timed out. Only {len(executed_defers)} of "
+                f"1000 defers executed. Missing IDs: "
+                f"{sorted(set(range(1000)) - executed_defers)[:10]}..."
+            )
+
+        # Verify all defers executed
+        assert len(executed_defers) == 1000, (
+            f"Expected 1000 defers, got {len(executed_defers)}"
+        )
+
+        # Verify we have all IDs from 0-999
+        expected_ids = set(range(1000))
+        missing_ids = expected_ids - executed_defers
+        assert not missing_ids, f"Missing defer IDs: {sorted(missing_ids)}"
+
+        # Verify FIFO ordering was maintained within each thread
+        assert not fifo_violations, "FIFO ordering violations detected:\n" + "\n".join(
+            fifo_violations[:10]
+        )
+
+        # Verify each thread executed all its defers in order
+        for thread_id, indices in thread_executions.items():
+            assert len(indices) == 100, (
+                f"Thread {thread_id} executed {len(indices)} defers, expected 100"
+            )
+            # Indices should be 0-99 in ascending order
+            assert indices == list(range(100)), (
+                f"Thread {thread_id} executed indices out of order: {indices[:10]}..."
+            )
+
+        # If we got here without crashing and with proper ordering, the test passed
+        assert True, (
+            "Test completed successfully - all 1000 defers executed with "
+            "FIFO ordering preserved"
+        )