How to prevent task from exiting

I have a long term task like watching file by myself, I just don't like it exits after my task is running. I tried `wait` but blocks the thread. Now I using `repl` to force the task running.

However `repl` turned out to cost me some resource. Is there a better solution?

To be more specific, I'm [firing a ring server in my task](https://github.com/mvc-works/stack-workflow/blob/master/build.boot#L64), and it exits as the task finishes. Normally a ring server will make the process running. So it's a bit strange in Boot here.