ch9/ch9-08

[giscus[bot]]

ch9/ch9-08

中文版

https://gopl-zh.github.io/ch9/ch9-08.html

[Zengyinjun]

9.4 不太懂但是内存确实占用了

func liu(a chan int) {
	for {
		i := <-a
		fmt.Println(i + 1)
		b := make(chan int)
		go liu(b)
		b <- i + 1
	}
}
func main() {
	a := make(chan int)
	// b := make(chan int)
	go liu(a)
	a <- 1
	for {
	}
}

[scutBCH]

9.5

func pingPong(in chan int, out chan int) {
	for {
		count := <-in
		out <- count + 1
	}
}

func main() {
	ping := make(chan int)
	pong := make(chan int)
	go pingPong(ping, pong)
	go pingPong(pong, ping)

	ping <- 0
	time.Sleep(1 * time.Second)

	counter := <-ping
	fmt.Println("counter: ", counter)  // 3623866
}

[coderZoe]

最后的 counter := <-ping 会在1s后消费最终的count值，这个ping是由第二个go routine生产，而由第一个go routine消费，会不会有种可能1s后，第二个go routine生产的ping一直被第一个go routine消费，而main无法消费到，导致main死锁或者main消费到的时候已经远超1s后的情况呢

[Arickkaa]

func main() {
	done := make(chan bool)
	ch1, ch2 := make(chan string), make(chan string)
	var count1, count2 int
	go func() {
		for {
			select {
			case <-done:
				fmt.Println("Goroutine 1 Done")
				return
			case ch1 <- "ping-pong":
				<-ch2
				count1++
			}
		}
	}()
	go func() {
		for {
			select {
			case <-done:
				fmt.Println("Goroutine 2 Done")
				return
			case <-ch1:
				ch2 <- "ping-pong"
				count2++
			}
		}
	}()
	time.Sleep(1 * time.Second)
	close(done)
	time.Sleep(100 * time.Millisecond)
	fmt.Println(count1 + count2)
}

[Arickkaa]

9.5，大概5405750

[a-firefly]

16GB 内存的M1 芯片的iMac能创建36219000 多个 goroutine。

func main() {
	nums := make(chan int)
	go func() {
		var max int64
		for {
			max++
			if max % 1000 == 0 {
				println(max)
			}
			go func() {
				<-nums
			}()
		}
	}()

	<-nums
}

输出：

...
36219000
signal: killed

[a-firefly]

9.5

package main

import (
	"fmt"
	"time"
)

func main() {
	numPi := 0
	numPo := 0
	pings := make(chan string)
	pongs := make(chan string)
	tick := time.Tick(1 * time.Second)

	go func() {
		for {
			pings <- "ping"
		}
	}()

	go func() {
		for {
			pongs <- "pong"
		}
	}()

	loop:
	for {
		select {
		case <- tick:
			break loop
		case <-pings:
			numPi++
		case <-pongs:
			numPo++
		}
	}

	fmt.Printf("ping: %d, pong: %d\n", numPi, numPo)
}

输出

ping: 1623912, pong: 1745154