Concurrency in Go: Concurrent Map Writes

// There's no proper UUID package still, so we'll deal with floats
m := make(map[float64]float64)

// This will allow us to wait for all goroutines to complete
doneChannel := make(chan bool, 10)

// Launch goroutines
for i := 0; i < 10; i++ {
       go func() {
              // Generate some random numbers
              for i := 0; i < 1000; i++ {
                     f := rand.Float64()
                     m[f] = f
              }
              // Notify when done
              doneChannel <- true
       }()
}

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

// Crash! fatal error: concurrent map writes!
fmt.Println(len(m))