// A concurrent prime sieve
package main
import "fmt"
// Send the sequence 2, 3, 4, ... to channel 'ch'.
func Generate(ch chan<- int) {
    for i := 2; ; i++ {
        ch <- i // Send 'i' to channel 'ch'.
    }
}
// Copy the values from channel 'in' to channel 'out',
// removing those divisible by 'prime'.
func Filter(in <-chan int, out chan<- int, prime int) {
    for {
        i := <-in // Receive value from 'in'.
        if i%prime != 0 {
            out <- i // Send 'i' to 'out'.
        }
    }
}
// The prime sieve: Daisy-chain Filter processes.
func main() {
    ch := make(chan int) // Create a new channel.
    go Generate(ch)      // Launch Generate goroutine. 建立chan 从2开始依次填入数据，因为无缓冲， 当值被取走后才会结束阻塞
    for i := 0; i < 10; i++ { //重复执行10次 取前10个质数
        prime := <-ch  //取值 第一个是2 后面chan会被替换 ，数字被过滤
        fmt.Println(prime) 
        ch1 := make(chan int)
        go Filter(ch, ch1, prime) //过滤旧chan数据 转移到新chan （过滤掉被该质数整除的数）
        ch = ch1 //替换chan
    }
}

package main
func main() {
    // create new channel of type int
    ch := make(chan int)
    // start new anonymous goroutine
    go func() {
        // send 42 to channel
        ch <- 42
    }()
    // read from channel
    <-ch
}

package main
import "time"
func timer(d time.Duration) <-chan int {
    c := make(chan int)
    go func() {
        time.Sleep(d)
        c <- 1
    }()
    return c
}
func main() {
    for i := 0; i < 24; i++ {
        c := timer(1 * time.Second)
        <-c
    }
}

package main
import "time"
func main() {
    var Ball int
    table := make(chan int)
    go player(table)
    go player(table)
    table <- Ball
    time.Sleep(1 * time.Second)
    <-table
}
func player(table chan int) {
    for {
        ball := <-table
        ball++
        time.Sleep(100 * time.Millisecond)
        table <- ball
    }
}

 go player(table)
    go player(table)
    go player(table)

参考：https://www.cloudbees.com/blog/visualizing-concurrency-go