前言
- atomic 适用的场景 - 简单、简单、简单！不要将atomic用在复杂的业务逻辑中
- atomic.Value 与 mutex - 学习用两者解决问题的思路
- 了解 data race 机制 - atomic可以有效地减少数据竞争
代码
package mainimport ("fmt""sync""sync/atomic"
)func atomicAdd() {var data, data2 int64var wg sync.WaitGroupfor i := 0; i < 1000; i++ {wg.Add(1)go func() {atomic.AddInt64(&data, 1)data2++wg.Done()}()}wg.Wait()fmt.Println("data", data, "data2", data2)
}// From medium: https://medium.com/a-journey-with-go/go-how-to-reduce-lock-contention-with-the-atomic-package-ba3b2664b549
type Config struct {a []int
}// 用 go run -race main.go atomic.go 观察data races
func dataRaces() {cfg := &Config{}go func() {i := 0for {i++cfg.a = []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}}}()var wg sync.WaitGroupfor n := 0; n < 4; n++ {wg.Add(1)go func() {for n := 0; n < 100; n++ {fmt.Printf("%v\n", cfg)}wg.Done()}()}wg.Wait()
}func dataRacesWithLock() {var mu sync.RWMutexcfg := &Config{}go func() {i := 0for {i++mu.Lock()cfg.a = []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}mu.Unlock()}}()var wg sync.WaitGroupfor n := 0; n < 4; n++ {wg.Add(1)go func() {for n := 0; n < 100; n++ {mu.RLock()fmt.Printf("%v\n", cfg)mu.RUnlock()}wg.Done()}()}wg.Wait()
}func dataRacesWithAtomic() {var v atomic.Valuego func() {i := 0for {i++cfg := &Config{a: []int{i, i + 1, i + 2, i + 3, i + 4, i + 5}}v.Store(cfg)}}()var wg sync.WaitGroupfor n := 0; n < 4; n++ {wg.Add(1)go func() {for n := 0; n < 100; n++ {cfg := v.Load()fmt.Printf("%v\n", cfg)}wg.Done()}()}wg.Wait()
}// cas相关的代码，建议直接参考源码中的相关实现
