golang 并发编程之生产者消费者详解

go func () {
    // do something
}

var wg sync.WaitGroup  // 申明一个信号量
wg.Add(1)   // 信号量加一
wg.Done()   // 信号量减一
wg.Wait()   // 信号量为正时阻塞，直到信号量为0时被唤醒

ic := make(chan int, 10)  // 申明一个通道
ic <- 10        // 往通道里面放
i := <- ic      // 从通道里面取
close(ic)       // 关闭通道

type Product struct {
    name  int
    value int
}

func producer(wg *sync.WaitGroup, products chan<- Product, name int, stop *bool) {
    for !*stop {
        product := Product{name: name, value: rand.Int()}
        products <- product
        fmt.Printf("producer %v produce a product: %#v\n", name, product)
        time.Sleep(time.Duration(200+rand.Intn(1000)) * time.Millisecond)
    }
    wg.Done()
}

func consumer(wg *sync.WaitGroup, products <-chan Product, name int) {
    for product := range products {
        fmt.Printf("consumer %v consume a product: %#v\n", name, product)
        time.Sleep(time.Duration(200+rand.Intn(1000)) * time.Millisecond)
    }
    wg.Done()
}

var wgp sync.WaitGroup
var wgc sync.WaitGroup
stop := false
products := make(chan Product, 10)
// 创建 5 个生产者和 5 个消费者
for i := 0; i < 5; i++ {
    go producer(&wgp, products, i, &stop)
    go consumer(&wgc, products, i)
    wgp.Add(1)
    wgc.Add(1)
}
time.Sleep(time.Duration(1) * time.Second)
stop = true     // 设置生产者终止信号
wgp.Wait()      // 等待生产者退出
close(products) // 关闭通道
wgc.Wait()      // 等待消费者退出

package main
import (
    "fmt"
    "time"
)
var ch1 chan int = make(chan int)
var bufChan chan int = make(chan int, 1000)
var msgChan chan int = make(chan int)
func sum(a int, b int) {
    ch1 <- a + b
}
// write data to channel
func writer(max int) {
    for {
        for i := 0; i < max; i++ {  // 简单的向channel中放入一个整数
            bufChan <- i
            time.Sleep(1 * time.Millisecond)  //控制放入的频率
        }
    }
}
// read data fro m channel
func reader(max int) {
    for {
        r := <-bufChan
        fmt.Printf("read value: %d\n", r)
    }
    // 通知主线程，工作结束了，这一步可以省略
    msgChan <- 1
}
func testWriterAndReader(max int) {
    go writer(max)
    go reader(max)
    // writer 和reader的任务结束了，主线程会得到通知 
    res := <-msgChan
    fmt.Printf("task is done: value=%d\n", res)
}
func main() {
    testWriterAndReader(100)
}

package main
import (
    "time"
    "fmt"
    "os"
)
var ch1 chan int = make(chan int)
var bufChan chan int = make(chan int, 1000)
var msgChan chan string = make(chan string)
func sum(a int, b int) {
    ch1 <- a + b
}
// write data to channel
func writer(max int) {
    for {
        for i := 0; i < max; i++ {
            bufChan <- i
            fmt.Fprintf(os.Stderr, "%v write: %d\n", os.Getpid(), i)
            time.Sleep(10 * time.Millisecond)
        }
    }
}
// read data fro m channel
func reader(name string) {
    for {
        r := <-bufChan
        fmt.Printf("%s read value: %d\n", name, r)
    }
    msgChan <- name
}
func testWriterAndReader(max int) {
    // 开启多个writer的goroutine，不断地向channel中写入数据
    go writer(max)
    go writer(max)
    // 开启多个reader的goroutine，不断的从channel中读取数据，并处理数据
    go reader("read1")
    go reader("read2")
    go reader("read3")
    // 获取三个reader的任务完成状态
    name1 := <-msgChan
    name2 := <-msgChan
    name3 := <-msgChan
    fmt.Println("%s,%s,%s: All is done!!", name1, name2, name3)
}
func main() {
    testWriterAndReader(100)
}