C :: How To Suspend An Ongoing Task

Here is what I am trying to do. I am reading from a socket. On receipt of specific data from the socket I have to start some computation (takes more than 5s). But if there is another input from the socket when the computation is in progress I need to disregard the ongoing computation and start all afresh. I have not come across any method which could suspend the ongoing task in the same context. I have thought of running computation in a separate thread. But I feel there must be some other methods doing it in the same context which I am unaware of. And, is my understanding correct that process would take up the new task only after completing the previous computation (which I do not want).