Understand Race Condition with Go

testUnderstandRaceCondition.go

package main

import (
	"fmt"
	"time"
	"sync/atomic"
)


var start time.Time
var elapsed time.Duration
var channel chan bool

var counter int

func DoCount (duration time.Duration) {
	value := counter
	time.Sleep(duration)
	value++
	counter = value
}

func main() {


	// ==============================================================
	// Case non maintain race condition, task done in 1 nano second
	// ==============================================================

	counter = 0

	start = time.Now()

	// Simulate 1000 async requests from client side before listen command
	for request := 1; request <= 1000; request++ {
		go func () {
			DoCount(1*time.Nanosecond)
		}()
	}

	elapsed = time.Since(start)

	// Wait for ensure result
	time.Sleep(1*time.Second)

	fmt.Println("==================================================================")
	fmt.Println("Case non maintain race condition, task done in 1 nano second")
	fmt.Println("counter = ", counter)
	fmt.Println("spend time = ", elapsed)




	// ==============================================================
	// Case non maintain race condition, task done in 1 milli second
	// ==============================================================

	counter = 0

	start = time.Now()

	// Simulate 1000 async requests from client side before listen command
	for request := 1; request <= 1000; request++ {
		go func () {
			DoCount(10*time.Millisecond)
		}()
	}

	elapsed = time.Since(start)

	// Wait for ensure result
	time.Sleep(1*time.Second)


	fmt.Println("==================================================================")
	fmt.Println("Case non maintain race condition, task done in 1 milli second")
	fmt.Println("counter = ", counter)
	fmt.Println("spend time = ", elapsed)



	// ==============================================================
	// Case maintain race condition, task done in 1 nano second
	// ==============================================================

	counter = 0

	start = time.Now()

	channel = make(chan bool)

	// Simulate 1000 async requests from client side before listen command
	for request := 1; request <= 1000; request++ {
		go func () {
			channel <- true
		}()
	}

	// Simulate replay task spend time 2 seconds
	time.Sleep(time.Second * 2)

	// Start listen command after replay task
	go func() {
		for {
			<-channel
			DoCount(1*time.Nanosecond)
		}
	}()

	elapsed = time.Since(start)

	// Wait for ensure result
	time.Sleep(1*time.Second)

	fmt.Println("==================================================================")
	fmt.Println("Case maintain race condition, task done in 1 nano second")
	fmt.Println("counter = ", counter)
	fmt.Println("spend time = ", elapsed)



	// ==============================================================
	// Case atomic add race condition, task done fastest
	// ==============================================================

	var atomicCounter uint64 = 0
	counter = 0

	start = time.Now()

	// Simulate 1000 async requests from client side before listen command
	for request := 1; request <= 1000; request++ {
		go func () {
			counter++
			atomic.AddUint64(&atomicCounter, 1)
		}()
	}

	elapsed = time.Since(start)

	// Wait for ensure result
	time.Sleep(1*time.Second)

	fmt.Println("==================================================================")
	fmt.Println("Case atomic add race condition, task done fastest")
	fmt.Println("counter = ", counter)
	fmt.Println("atomicCounter = ", atomicCounter)
	fmt.Println("spend time = ", elapsed)

}