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  • golang之包和锁的机制

    互斥锁

    同一时刻只有一个携程在操作

    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()
    }

    读写锁

    读多写少的情况,用读写锁, 携程同时在操作读。

    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
    }

    读写锁,互斥锁,性能比较

    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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  • 原文地址:https://www.cnblogs.com/pyyu/p/8186313.html
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