go 包-锁机制

时间:2023-03-09 17:54:45
go 包-锁机制

线程同步

  • import(“sync”)
  • 互斥锁, var mu sync.Mutex
  • 读写锁, var mu sync.RWMutex

资源竞争样例

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
a[18] = 10 for i := 0; i < 2; i++ {
go func(b map[int]int) {
b[8] = rand.Intn(100)
}(a)
} fmt.Println(a)
}

编译:go build -race go_dev\main

  • -race  资源竞争检测

执行程序会抛资源竞争错误

引入互斥锁解决上面的问题

package main

import (
"fmt"
"math/rand"
"sync"
"time"
) 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
a[18] = 10 for i := 0; i < 2; i++ {
go 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() {
testMap()
}

读写锁+原子操作

package main

import (
"fmt"
"math/rand"
"sync"
"sync/atomic"
"time"
) var lock sync.Mutex
var rwLock sync.RWMutex 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()
//lock.Lock()
b[8] = rand.Intn(100)
time.Sleep(10 * time.Millisecond)
//lock.Unlock()
rwLock.Unlock()
}(a)
} for i := 0; i < 100; i++ {
go func(b map[int]int) {
for {
//lock.Lock()
rwLock.RLock()
time.Sleep(time.Millisecond)
//fmt.Println(a)
rwLock.RUnlock()
//lock.Unlock()
atomic.AddInt32(&count, 1)
}
}(a)
}
time.Sleep(time.Second * 3)
fmt.Println(atomic.LoadInt32(&count))
} func main() {
testRWLock()
}