go sync包中的互斥锁Mutex和等待组WaitGroup使用详解

var m sync.Mutex

m.Lock()
// 临界区，只有获得锁的 Go Routine 才能访问
m.Unlock()

var m sync.Mutex

m.Lock()
// 临界区，只有获得锁的 Go Routine 才能访问
m.Unlock()

package main
import (
    "fmt"
    "sync"
    "time"
)
type SafeCounter struct {
    v   map[string]int
    mux sync.Mutex
}
func (c *SafeCounter) Inc(key string) {
    c.mux.Lock()
    c.v[key]++
    c.mux.Unlock()
}
func (c *SafeCounter) Value(key string) int {
    c.mux.Lock()
    defer c.mux.Unlock()
    return c.v[key]
}
func main() {
    c := SafeCounter{v: make(map[string]int)}
    for i := 0; i < 1000; i++ {
        go c.Inc("somekey")
    }
    time.Sleep(time.Second)
    fmt.Println(c.Value("somekey"))
}

var wg sync.WaitGroup

package main
import (
    "fmt"
    "sync"
    "time"
)
func worker(id int, wg *sync.WaitGroup) {
    defer wg.Done()
    fmt.Printf("Worker %d starting\n", id)
    time.Sleep(time.Second)
    fmt.Printf("Worker %d done\n", id)
}
func main() {
    var wg sync.WaitGroup
    for i := 1; i <= 5; i++ {
        wg.Add(1)
        go worker(i, &wg)
    }
    wg.Wait()
}