Concurrency in Go: Mutexes

m := make(map[float64]float64)

// Create mutex manually
mux := sync.Mutex{}
doneChannel := make(chan bool, 10)

for i := 0; i < 10; i++ {
       go func() {
             
              for i := 0; i < 1000; i++ {
                     f := rand.Float64()
                     
                     // Lock and unlock
                     mux.Lock()
                     m[f] = f
                     mux.Unlock()
              }
             
              doneChannel <- true
       }()
}

for i := 0; i < 10; i++ {
       <-doneChannel
}

// That's better: 10000
fmt.Println(len(m))