First build the program by typing the following command.

    go build main.go
    go run main.go

Then run the program by using following command.

     ./main google.com facebook.com hello.com http://golang.org

You can use flag "parallel" to set the limit of processing the requests otherwise it is set to 10 by default.

   ./main -parallel 3 google.com facebook.com hello.com http://golang.org