1.读写都加锁

package main

import (
    "fmt"
    "sync"
    "time"
)

var slice = make([]int64, 0)

func main() {
    var l sync.Mutex
    go func() {
        for {
            time.Sleep(time.Second)
            l.Lock()
            slice = append(slice, time.Now().Unix())
            l.Unlock()
        }
    }()

    for m := 0; m < 5; m++ {
        go func() {
            for {
                l.Lock()
                time.Sleep(time.Millisecond * 100)
                fmt.Println(len(slice))
                l.Unlock()
            }
        }()
    }
    time.Sleep(time.Hour)
}

2.读加锁，写不加锁

package main

import (
    "fmt"
    "sync"
    "time"
)

var slice = make([]int64, 0)

func main() {
    var l sync.RWMutex //读写锁
    go func() {
        for {
            time.Sleep(time.Second)
            l.Lock()
            slice = append(slice, time.Now().Unix())
            l.Unlock()
        }
    }()

    for m := 0; m < 5; m++ {
        go func() {
            for {
                l.RLock()
                time.Sleep(time.Millisecond * 100)
                fmt.Println(len(slice))
                l.RUnlock()
            }
        }()
    }

    time.Sleep(time.Hour)
}

3.原子加锁

package main

import (
    "fmt"
    "sync/atomic"
    "time"
    "unsafe"
)

var slice = &[]int{}
var slicePtr = unsafe.Pointer(slice)

func main() {
    go func() {
        for {
            time.Sleep(time.Second)
            slicePtr = atomic.LoadPointer(&slicePtr)
            slice1 := (*[]int64)(slicePtr)
            slice2 := append(*slice1, time.Now().UnixNano())
            atomic.StorePointer(&slicePtr, unsafe.Pointer(&slice2))
        }
    }()

    for m := 0; m < 5; m++ {
        go func() {
            for {
                time.Sleep(time.Millisecond * 100)
                ptr := atomic.LoadPointer(&slicePtr)
                slice := (*[]int64)(ptr)
                fmt.Println(len(*slice))
            }
        }()
    }

    time.Sleep(time.Hour)
}