how_many_blocked_threads.go

package main

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

func main() {
    wg := new(sync.WaitGroup)
    for i := 0; i < 355; i++ {
        wg.Add(1)
        go func(i int) {
            fmt.Println("Starting sleep ", i, "...")
            cmd := exec.Command("sleep", "3600")
            _, err := cmd.Output()
            if err != nil {
                panic(err)
            }
            fmt.Println("Finishing sleep ", i, "...")
            wg.Done()
        }(i)
    }
    fmt.Println("Waiting for WaitGroup ...")
    wg.Wait()
    fmt.Println("WaitGroup finished!")
}

Testing it:

$ go run multiproc.go

$ ps -eLf | grep go-build | wc -l
691

... so only like 691 threads, for those 1000 go routines ...