The Solution — Use Concurrency, But Hold Your Horses

So how can we gain the performance benefits of concurrent code without setting up a shower of goroutines? Well, one nice way to limit concurrency in go is by using a Buffered Channel Semaphore. Buffered channels in go are a nice and easy way to block execution based on the number of concurrent units of actions we want to have.

We set a buffered channel with a capacity of 100, and when we spawn the goroutines to perform the asynchronous computation, we revert to using the synchronous version of MergeSort if there are already 100 workers (goroutines) busy with the computation: