package main
import (
 "fmt"
 "math/rand"
 "sync"
 "time"
)
//互斥锁
var lock sync.Mutex
func testMap() {
 var a map[int]int
 a = make(map[int]int, 5)
 a[8] = 10
 a[3] = 10
 a[2] = 10
 a[1] = 10
 for i := 0; i < 2; i++ {
 func(b map[int]int) {
 lock.Lock()
 b[8] = rand.Intn(100)
 lock.Unlock()
 }(a)
 }
 lock.Lock()
 fmt.Println(a)
 lock.Unlock()
 time.Sleep(time.Second)
}
func main() {
 //互斥锁
 testMap()
}

package main
import (
 "fmt"
 "math/rand"
 "sync"
 "time"
)
//读写锁
var rwLock sync.RWMutex
func testRWLock() {
 var a map[int]int
 a = make(map[int]int, 5)
 a[8] = 10
 a[3] = 10
 a[2] = 10
 a[1] = 10
 a[18] = 10
 for i := 0; i < 2; i++ {
 go func(b map[int]int) {
 rwLock.Lock()
 b[8] = rand.Intn(100)
 rwLock.Unlock()
 }(a)
 }
 for i := 0; i < 100; i++ {
 go func(b map[int]int) {
 rwLock.RLock() //读锁
 fmt.Println(a)
 rwLock.RUnlock()
 }(a)
 }
 time.Sleep(time.Second * 20)
}
func main() {
 
 testRWLock()
 //读多写少的时候,用读写锁
}

package main
import (
 "fmt"
 "math/rand"
 "sync"
 "sync/atomic"
 "time"
)
//读写锁
var rwLock sync.RWMutex
var lock sync.Mutex
func testRWLock() {
 var a map[int]int
 a = make(map[int]int, 5)
 var count int32
 a[8] = 10
 a[3] = 10
 a[2] = 10
 a[1] = 10
 a[18] = 10
 for i := 0; i < 2; i++ {
 go func(b map[int]int) {
 //rwLock.Lock() //读写锁的代码
 lock.Lock() //互斥锁的代码
 b[8] = rand.Intn(100)
 time.Sleep(10 * time.Microsecond) //微妙
 //rwLock.Unlock()
 lock.Unlock()
 }(a)
 }
 for i := 0; i < 100; i++ {
 go func(b map[int]int) {
 for {
 //rwLock.RLock() //读写锁的代码
 lock.Lock()
 time.Sleep(time.Millisecond)
 //rwLock.RUnlock()
 lock.Unlock()
 atomic.AddInt32(&count, 1)
 }
 }(a)
 }
 time.Sleep(time.Second * 20)
 fmt.Println(atomic.LoadInt32(&count))
}
func main() {
 //互斥锁
 testRWLock()
 //读多写少的时候,用读写锁
}

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