You will need a barrier, the wait Group in your case, to guarantee the main
goroutine will only continue after all the others have finished their work.
Besides if any of your goroutines blocks due to IO the Go scheduler will
look for another goroutine to run while the blocked one waits.
Another
As I understand, it will execute in parallel by default. There's a pool of
threads for running goroutines, defaulting initially to the number of
cores. If a syscall blocks, then other threads will continue to run - and
(I think) an extra thread is started too.
> But still I had to use
