Terminate current process of a button click event

Hi all,

 

         I have one web applicaiton, in which I have two buttons., each button handle different long running operations.

 

         For example, I click the Button 1 and the long running operation started, if now immediately I click the button 2 mean,  we have to terminate all the process running under Button 1_CLick event and force to do only the operation under Button_2 click event.

 

       How can I achieve this, can anyone please help me ?

 

Thanks in advance..