package main

import (
    "fmt"
    "os"
    "runtime"
    "runtime/trace"
    "time"
    debug "runtime/debug"
)

func child(c chan string) {
    for msg := range c {
        c <- msg
    }
}

func main() {
    f, err := os.Create("trace.out")
    if err != nil {
        panic(err)
    }
    defer f.Close()

    if err := trace.Start(f); err != nil {
        panic(err)
    }
    defer trace.Stop()

    runtime.GOMAXPROCS(1)
    debug.SetGCPercent(-1)

    c := make(chan string)
    go child(c)

    const niters = 2000000
    for i := 0; i < niters; i++ {
        c <- "test"
        reply := <-c
        if len(reply) != 4 {
            panic("err")
        }
    }

    fmt.Println("done")
    time.Sleep(1 * time.Second)
}