[echokit_server](https://github.com/second-state/echokit_server/tree/main)/[src](https://github.com/second-state/echokit_server/tree/main/src)/[services](https://github.com/second-state/echokit_server/tree/main/src/services)/[ws](https://github.com/second-state/echokit_server/tree/main/src/services/ws)/[stable](https://github.com/second-state/echokit_server/tree/main/src/services/ws/stable)/mod.rs#L279 处有一个 tts 的 session poll，本质是一个协程池，优化成可以根据请求繁忙程度动态调整在没有达到最大请求数量时可以自动增加 worker，new 的入参 workers 改成 idle_workers(空闲时保留的 worker 数量) + max_workers(最大的 worker 数量) + idle_timeout
