go 协程
更多干货
代码地址：
https://github.com/csy512889371/learndemo/tree/master/go/golearn
概述
-
goroutine 可能切换的点
-
非强占式
-
I/O ,select
-
channel
-
等待锁
-
调用函数
-
runtime.Gosched()
-
只是参考，不能保证切换
-
代码channel
package main
import (
"fmt"
"time"
)
func worker(id int, c chan int) {
for n := range c {
fmt.Printf("Worker %d received %c\n",
id, n)
}
}
func createWorker(id int) chan<- int {
c := make(chan int)
go worker(id, c)
return c
}
func chanDemo() {
var channels [10]chan<- int
for i := 0; i < 10; i++ {
channels[i] = createWorker(i)
}
for i := 0; i < 10; i++ {
channels[i] <- 'a' + i
}
for i := 0; i < 10; i++ {
channels[i] <- 'A' + i
}
time.Sleep(time.Millisecond)
}
func bufferedChannel() {
c := make(chan int, 3)
go worker(0, c)
c <- 'a'
c <- 'b'
c <- 'c'
c <- 'd'
time.Sleep(time.Millisecond)
}
func channelClose() {
c := make(chan int)
go worker(0, c)
c <- 'a'
c <- 'b'
c <- 'c'
c <- 'd'
close(c)
time.Sleep(time.Millisecond)
}
func main() {
fmt.Println("Channel as first-class citizen")
chanDemo()
fmt.Println("Buffered channel")
bufferedChannel()
fmt.Println("Channel close and range")
channelClose()
}select 代码
package main
import (
"fmt"
"math/rand"
"time"
)
func generator() chan int {
out := make(chan int)
go func() {
i := 0
for {
time.Sleep(
time.Duration(rand.Intn(1500)) *
time.Millisecond)
out <- i
i++
}
}()
return out
}
func worker(id int, c chan int) {
for n := range c {
time.Sleep(time.Second)
fmt.Printf("Worker %d received %d\n",
id, n)
}
}
func createWorker(id int) chan<- int {
c := make(chan int)
go worker(id, c)
return c
}
func main() {
var c1, c2 = generator(), generator()
var worker = createWorker(0)
var values []int
tm := time.After(10 * time.Second)
tick := time.Tick(time.Second)
for {
var activeWorker chan<- int
var activeValue int
if len(values) > 0 {
activeWorker = worker
activeValue = values[0]
}
select {
case n := <-c1:
values = append(values, n)
case n := <-c2:
values = append(values, n)
case activeWorker <- activeValue:
values = values[1:]
case <-time.After(800 * time.Millisecond):
fmt.Println("timeout")
case <-tick:
fmt.Println(
"queue len =", len(values))
case <-tm:
fmt.Println("bye")
return
}
}
}done 代码
package main
import (
"fmt"
"sync"
)
func doWork(id int,
w worker) {
for n := range w.in {
fmt.Printf("Worker %d received %c\n",
id, n)
w.done()
}
}
type worker struct {
in chan int
done func()
}
func createWorker(
id int, wg *sync.WaitGroup) worker {
w := worker{
in: make(chan int),
done: func() {
wg.Done()
},
}
go doWork(id, w)
return w
}
func chanDemo() {
var wg sync.WaitGroup
var workers [10]worker
for i := 0; i < 10; i++ {
workers[i] = createWorker(i, &wg)
}
wg.Add(20)
for i, worker := range workers {
worker.in <- 'a' + i
}
for i, worker := range workers {
worker.in <- 'A' + i
}
wg.Wait()
}
func main() {
chanDemo()
}