source: benchmark/readyQ/churn.go @ 90a8125

package main

import (
        "flag"
        "fmt"
        "math/rand"
        "runtime"
        "sync"
        "sync/atomic"
        "time"
        "golang.org/x/text/language"
        "golang.org/x/text/message"
)

func churner(result chan uint64, start *sync.WaitGroup, spots [] chan struct {}) {
        s := rand.NewSource(time.Now().UnixNano())
        rng := rand.New(s)

        count := uint64(0)
        start.Wait()
        for true {

                sem := spots[ rng.Intn(100) % len(spots) ];
                sem <- (struct {}{})
                <- sem;

                count += 1
                if  clock_mode && atomic.LoadInt32(&stop) == 1 { break }
                if !clock_mode && count >= stop_count { break }
        }

        atomic.AddInt64(&threads_left, -1);
        result <- count
}

func main() {
        var spot_cnt int

        spot_cntOpt := flag.Int("s", 1, "Number of spots in the system")

        bench_init()

        spot_cnt = *spot_cntOpt

        threads_left = int64(nthreads)

        result := make(chan uint64)
        var wg sync.WaitGroup
        wg.Add(1)

        spots := make([] chan struct {}, spot_cnt)
        for i := range spots {
                spots[i] = make(chan struct {}, 1)
        }

        for i := 0; i < nthreads; i++ {
                go churner(result, &wg, spots)
        }
        fmt.Printf("Starting\n");
        atomic.StoreInt32(&stop, 0)
        start := time.Now()
        wg.Done();
        wait(start, true);

        atomic.StoreInt32(&stop, 1)
        end := time.Now()
        duration := end.Sub(start)

        fmt.Printf("\nDone\n")

        for atomic.LoadInt64(&threads_left) != 0 {
                for i := range spots {
                        select {
                        case spots[i] <- (struct {}{}):
                        default:
                        }
                        runtime.Gosched()
                }
        }

        global_counter := uint64(0)
        for i := 0; i < nthreads; i++ {
                global_counter += <- result
        }

        p := message.NewPrinter(language.English)
        p.Printf("Duration (ms)        : %d\n", duration.Milliseconds())
        p.Printf("Number of processors : %d\n", nprocs);
        p.Printf("Number of threads    : %d\n", nthreads);
        p.Printf("Number of spots      : %d\n", spot_cnt);
        p.Printf("Total Operations(ops): %15d\n", global_counter);
        // p.Printf("Total blocks         : %15d\n", global_blocks);
        p.Printf("Ops per second       : %18.2f\n", float64(global_counter) / duration.Seconds());
        p.Printf("ns per ops           : %18.2f\n", float64(duration.Nanoseconds()) / float64(global_counter))
        p.Printf("Ops per threads      : %15d\n", global_counter / uint64(nthreads))
        p.Printf("Ops per procs        : %15d\n", global_counter / uint64(nprocs))
        p.Printf("Ops/sec/procs        : %18.2f\n", (float64(global_counter) / float64(nprocs)) / duration.Seconds())
        p.Printf("ns per ops/procs     : %18.2f\n", float64(duration.Nanoseconds()) / (float64(global_counter) / float64(nprocs)))
}