modify: ruff 清理 + 单例锁持有者释放 + 移除死代码

verify_example_plugin.py

@@ -16,7 +16,7 @@ def check(name, cond, detail=""):
 
 
 # ========== 1. global_var 白名单 / require / __all__ ==========
-from plugins.example import global_var as gv
+from plugins.example import global_var as gv  # noqa: E402
 
 check("global_var.__all__ 包含 db", "db" in gv.__all__)
 check("global_var.__all__ 包含 set_global_var", "set_global_var" in gv.__all__)
@@ -45,7 +45,7 @@ check("模块属性 db 已被更新", gv.db is marker)
 
 
 # ========== 2. __init__.py 导入链（router + Plugin 基类）==========
-import plugins.example as plug
+import plugins.example as plug  # noqa: E402
 
 check("plugins.example 导入成功", True)
 check("create_workers 存在", callable(getattr(plug, "create_workers", None)))
@@ -54,7 +54,7 @@ check("plugin 实例存在", getattr(plug, "plugin", None) is not None)
 check("plugin._initialized 默认 False", plug.plugin._initialized is False)
 
 # ========== 3. create_workers 幂等性（mock session/config）==========
-import asyncio
+import asyncio  # noqa: E402
 
 # 用桩替代 Plugin 基类的 worker 创建实现，避免真实 zenoh 会话
 calls = []