concurrency-3.go

func parallelMergesortV1(s []int) {
    if len(s) <= 1 {
        return
    }

    middle := len(s) / 2

    var wg sync.WaitGroup
    wg.Add(2)

    go func() { // Spins up the first half of the work in a goroutine
        defer wg.Done()
        parallelMergesortV1(s[:middle])
    }()

    go func() { // Spins up the second half of the work in a goroutine
        defer wg.Done()
        parallelMergesortV1(s[middle:])
    }()

    wg.Wait()
    merge(s, middle) // Merges the halves
}