014.golang 并发concurrency
发布时间:2020-12-16 19:18:16 所属栏目:大数据 来源:网络整理
导读:并发concurrency 很多人都是冲着 Go 大肆宣扬的高并发而忍不住跃跃欲试,但其实从 源码的解析来看,goroutine 只是由官方实现的超级“线程池”而已。 不过话说回来,每个实例 4-5KB 的栈内存占用和由于实现机制而大幅 减少的创建和销毁开销,是制造 Go 号称
并发concurrency
package main
import (
"fmt"
"time"
)
func main() {
go Go()
time.Sleep(time.Second)
}
func Go() {
fmt.Println("Go GO Go ...")
}
Channel
package main
import (
"fmt"
"runtime"
)
func main() {
runtime.GOMAXPROCS(runtime.NumCPU())
c := make(chan bool, 10)
for i := 0; i < 10; i++ {
go Go(c,i)
}
for i := 0; i < 10; i++ {
<-c
}
}
func Go(c chan bool,index int) {
a := 1
for i := 0; i < 10000000; i++ {
a += i
}
fmt.Println(index,a)
c <- true
}
package main
import (
"fmt"
)
func main() {
c := make(chan bool)
go func() {
fmt.Println("Go Go Go ...")
c <- true
}()
<-c
}
package main
import (
"fmt"
)
func main() {
c := make(chan bool)
go func() {
fmt.Println("Go Go Go ...")
c <- true
close(c)
}()
for v := range c {
fmt.Println(v)
}
}
package main
import (
"fmt"
"runtime"
"sync"
)
func main() {
runtime.GOMAXPROCS(runtime.NumCPU())
wg := sync.WaitGroup{}
wg.Add(10)
for i := 0; i < 10; i++ {
go Go(&wg,i)
}
wg.Wait()
}
func Go(wg *sync.WaitGroup,index int) {
a := 1
for i := 0; i < 10000000; i++ {
a += i
}
fmt.Println(index,a)
wg.Done()
}
Select
package main
import (
"fmt"
)
func main() {
c1,c2 := make(chan int),make(chan string)
o := make(chan bool)
go func() {
for {
select {
case v,ok := <-c1:
if !ok {
o <- true
break
}
fmt.Println("c1",v)
case v,ok := <-c2:
if !ok {
o <- true
break
}
fmt.Println("c2",v)
}
}
}()
c1 <- 1
c2 <- "hello"
c1 <- 2
c2 <- "world"
close(c1)
close(c2)
<-o
}
package main
import (
"fmt"
)
func main() {
//随机输出 0 或 1
c := make(chan int)
go func() {
for v := range c {
fmt.Println(v)
}
}()
for {
select {
case c <- 0:
case c <- 1:
}
}
}
package main
import (
"fmt"
"time"
)
func main() {
c := make(chan bool)
select {
case v := <-c:
fmt.Println(v)
case <-time.After(3 * time.Second):
fmt.Println("Timeout")
}
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