refactor(runtime): lazily activate host modules (#6331)

tests/test_singleton_thread_safety.py

@@ -0,0 +1,41 @@
+import threading
+
+from app.foundation.singleton import Singleton, SingletonClass
+
+
+def _construct_concurrently(singleton_type, count: int = 16):
+    """让多个线程同时越过起跑线，放大首次构造竞态。"""
+    barrier = threading.Barrier(count)
+    instances = []
+
+    def construct() -> None:
+        barrier.wait()
+        instances.append(singleton_type())
+
+    threads = [threading.Thread(target=construct) for _ in range(count)]
+    for thread in threads:
+        thread.start()
+    for thread in threads:
+        thread.join(timeout=5)
+        assert not thread.is_alive()
+    return instances
+
+
+def test_parameterized_singleton_first_construction_is_single_flight():
+    """同一参数的并发首次构造只能发布一个完整实例。"""
+    class _ParameterizedSingleton(metaclass=Singleton):
+        pass
+
+    instances = _construct_concurrently(_ParameterizedSingleton)
+
+    assert len({id(instance) for instance in instances}) == 1
+
+
+def test_class_singleton_first_construction_is_single_flight():
+    """按类单例的并发首次构造只能发布一个完整实例。"""
+    class _ClassSingleton(metaclass=SingletonClass):
+        pass
+
+    instances = _construct_concurrently(_ClassSingleton)
+
+    assert len({id(instance) for instance in instances}) == 1