In reply to Prawin kumar:
I can see you code, but it is not really simulating. It proceeds only in time but does not issue any uvm_info with the exception of the build_phase.
Lookin to your code I see strange things in your sequence:
start_item(req);
assert (req.randomize());
req.delay = $urandom_range(1, 20);
req.int_a = $urandom();
req.int_b =$urandom();
finish_item(req);
You are randomizing twice. First with the randomize meothod belonging to the classes, which is fine and then randomizing with $urandom, which is not good.