github.com/hikaru7719/go@v0.0.0-20181025140707-c8b2ac68906a/test/fixedbugs/issue19182.go (about)

     1  // run
     2  // +build !js
     3  
     4  // Copyright 2017 The Go Authors. All rights reserved.
     5  // Use of this source code is governed by a BSD-style
     6  // license that can be found in the LICENSE file.
     7  
     8  package main
     9  
    10  import (
    11  	"fmt"
    12  	"runtime"
    13  	"sync/atomic"
    14  	"time"
    15  )
    16  
    17  var a uint64 = 0
    18  
    19  func main() {
    20  	runtime.GOMAXPROCS(2) // With just 1, infinite loop never yields
    21  
    22  	go func() {
    23  		for {
    24  			atomic.AddUint64(&a, uint64(1))
    25  		}
    26  	}()
    27  
    28  	time.Sleep(10 * time.Millisecond) // Short sleep is enough in passing case
    29  	i, val := 0, atomic.LoadUint64(&a)
    30  	for ; val == 0 && i < 100; val, i = atomic.LoadUint64(&a), i+1 {
    31  		time.Sleep(100 * time.Millisecond)
    32  	}
    33  	if val == 0 {
    34  		fmt.Printf("Failed to observe atomic increment after %d tries\n", i)
    35  	}
    36  
    37  }