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Puzzle 22 Explanation: Go Count

Puzzle 22 Explanation: Go Count

Understand how different packages work in Go.

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Try it yourself

Try executing the code below to see the result.

Go (1.16.5)
package main
import (
	"fmt"
	"sync"
)
func main() {
	var count int
	var wg sync.WaitGroup
	for i := 0; i < 1_000_000; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			count++
		}()
	}
	wg.Wait()
	fmt.Println(count)
}

Explanation

What we have here is a race condition. We don’t have an atomic operation, which means the code to increment an integer is interrupted mid-operation. Besides, there is the memory barrier. To speed things up, modern computers try to fetch values from a CPU cache before going the long way to the main memory. ...