Ubus not reponseding case

Hi All,
My issue:
I have created 2 services as p1 and p2. i call a method of p2 from p1 by using ubus_invoke_async(). In normal, if everything ok, p2 will reply to p1.
My question is: How i can handle if p2 doesn't send any repy to p1, p1 doesn't anything from p2. In this case, p2 is hangs.

Anyone can help me resolve this issue.