read_all_chans.go

package main

import (
    "bytes"
    "fmt"
    "os/exec"
    "sync"
)

func main() {
    wg := new(sync.WaitGroup)
    for i := 0; i < 5000; i++ {
        wg.Add(1)
        go func(i int) {
            fmt.Println("Starting sleep ", i, "...")
            cmd := exec.Command("sleep", "3600")
            cmdOut := &bytes.Buffer{}
            cmd.Stdout = cmdOut
            err := cmd.Start()
            if err != nil {
                panic(err)
            }
            cmd.Wait()
            fmt.Println("Finishing sleep ", i, "...")
            wg.Done()
        }(i)
    }
    fmt.Println("Waiting for WaitGroup ...")
    wg.Wait()
    fmt.Println("WaitGroup finished!")
}