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)

for i := 0; i < 100; i++ {
    go player(table)
}

package main
import (
    "fmt"
    "time"
)
func producer(ch chan int, d time.Duration) {
    var i int
    for {
        ch <- i
        i++
        time.Sleep(d)
    }
}
func reader(out chan int) {
    for x := range out {
        fmt.Println(x)
    }
}
func main() {
    ch := make(chan int)
    out := make(chan int)
    go producer(ch, 100*time.Millisecond)
    go producer(ch, 250*time.Millisecond)
    go reader(out)
    for i := range ch {
        out <- i
    }
}

package main
import (
    "fmt"
    "sync"
    "time"
)
func worker(tasksCh <-chan int, wg *sync.WaitGroup) {
    defer wg.Done()
    for {
        task, ok := <-tasksCh
        if !ok {
            return
        }
        d := time.Duration(task) * time.Millisecond
        time.Sleep(d)
        fmt.Println("processing task", task)
    }
}
func pool(wg *sync.WaitGroup, workers, tasks int) {
    tasksCh := make(chan int)
    for i := 0; i < workers; i++ {
        go worker(tasksCh, wg)
    }
    for i := 0; i < tasks; i++ {
        tasksCh <- i
    }
    close(tasksCh)
}
func main() {
    var wg sync.WaitGroup
    wg.Add(36)
    go pool(&amp;wg, 36, 50)
    wg.Wait()
}

package main
import (
    "fmt"
    "sync"
    "time"
)
const (
    WORKERS    = 5
    SUBWORKERS = 3
    TASKS      = 20
    SUBTASKS   = 10
)
func subworker(subtasks chan int) {
    for {
        task, ok := <-subtasks
        if !ok {
            return
        }
        time.Sleep(time.Duration(task) * time.Millisecond)
        fmt.Println(task)
    }
}
func worker(tasks <-chan int, wg *sync.WaitGroup) {
    defer wg.Done()
    for {
        task, ok := <-tasks
        if !ok {
            return
        }
        subtasks := make(chan int)
        for i := 0; i < SUBWORKERS; i++ {
            go subworker(subtasks)
        }
        for i := 0; i < SUBTASKS; i++ {
            task1 := task * i
            subtasks <- task1
        }
        close(subtasks)
    }
}
func main() {
    var wg sync.WaitGroup
    wg.Add(WORKERS)
    tasks := make(chan int)
    for i := 0; i < WORKERS; i++ {
        go worker(tasks, &amp;wg)
    }
    for i := 0; i < TASKS; i++ {
        tasks <- i
    }
    close(tasks)
    wg.Wait()
}

package main
import "net"
func handler(c net.Conn) {
    c.Write([]byte("ok"))
    c.Close()
}
func main() {
    l, err := net.Listen("tcp", ":5000")
    if err != nil {
        panic(err)
    }
    for {
        c, err := l.Accept()
        if err != nil {
            continue
        }
        go handler(c)
    }
}

package main
import (
    "fmt"
    "net"
    "time"
)
func handler(c net.Conn, ch chan string) {
    ch <- c.RemoteAddr().String()
    c.Write([]byte("ok"))
    c.Close()
}
func logger(ch chan string) {
    for {
        fmt.Println(<-ch)
    }
}
func server(l net.Listener, ch chan string) {
    for {
        c, err := l.Accept()
        if err != nil {
            continue
        }
        go handler(c, ch)
    }
}
func main() {
    l, err := net.Listen("tcp", ":5000")
    if err != nil {
        panic(err)
    }
    ch := make(chan string)
    go logger(ch)
    go server(l, ch)
    time.Sleep(10 * time.Second)
}

package main
import (
    "net"
    "time"
)
func handler(c net.Conn, ch chan string) {
    addr := c.RemoteAddr().String()
    ch <- addr
    time.Sleep(100 * time.Millisecond)
    c.Write([]byte("ok"))
    c.Close()
}
func logger(wch chan int, results chan int) {
    for {
        data := <-wch
        data++
        results <- data
    }
}
func parse(results chan int) {
    for {
        <-results
    }
}
func pool(ch chan string, n int) {
    wch := make(chan int)
    results := make(chan int)
    for i := 0; i < n; i++ {
        go logger(wch, results)
    }
    go parse(results)
    for {
        addr := <-ch
        l := len(addr)
        wch <- l
    }
}
func server(l net.Listener, ch chan string) {
    for {
        c, err := l.Accept()
        if err != nil {
            continue
        }
        go handler(c, ch)
    }
}
func main() {
    l, err := net.Listen("tcp", ":5000")
    if err != nil {
        panic(err)
    }
    ch := make(chan string)
    go pool(ch, 4)
    go server(l, ch)
    time.Sleep(10 * time.Second)
}

// 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.
    for i := 0; i < 10; i++ {
        prime := <-ch
        fmt.Println(prime)
        ch1 := make(chan int)
        go Filter(ch, ch1, prime)
        ch = ch1
    }
}