mutex_atomic.go

package main

import (
	"sync"
	"sync/atomic"
	"testing"
)

func main() {
	// Parallel benchmark for text/template.Template.Execute on a single object.
	r := testing.Benchmark(func(b *testing.B) {
		var (
			m     sync.Mutex
			level int
			res   int
		)

		b.RunParallel(func(pb *testing.PB) {
			for pb.Next() {
				m.Lock()
				res = level
				m.Unlock()
			}
		})
	})

	println("use lock", r.String())

	r = testing.Benchmark(func(b *testing.B) {
		var (
			level int32
			res   int32
		)

		b.RunParallel(func(pb *testing.PB) {
			for pb.Next() {
				res = atomic.LoadInt32(&level)
			}
		})
	})

	println("use atomic", r.String())

}

use lock 50000000	        26.3 ns/op
use atomic 300000000	         4.36 ns/op