test/fixedbugs/issue11256.go

   1 // run
   2
   3 // Copyright 2015 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 // Test that stack barriers are reset when a goroutine exits without
   8 // returning.
   9
  10 package main
  11
  12 import (
  13         "runtime"
  14         "sync/atomic"
  15         "time"
  16 )
  17
  18 func main() {
  19         // Let the garbage collector run concurrently.
  20         runtime.GOMAXPROCS(2)
  21
  22         var x [100][]byte
  23
  24         for i := range x {
  25                 var done int32
  26
  27                 go func() {
  28                         // Use enough stack to get stack barriers, but
  29                         // not so much that we go over _FixedStack.
  30                         // There's a very narrow window here on most
  31                         // OSs, so we basically can't do anything (not
  32                         // even a time.Sleep or a channel).
  33                         var buf [1024]byte
  34                         buf[0]++
  35                         for atomic.LoadInt32(&done) == 0 {
  36                                 runtime.Gosched()
  37                         }
  38                         atomic.StoreInt32(&done, 0)
  39                         // Exit without unwinding stack barriers.
  40                         runtime.Goexit()
  41                 }()
  42
  43                 // Generate some garbage.
  44                 x[i] = make([]byte, 1024*1024)
  45
  46                 // Give GC some time to install stack barriers in the G.
  47                 time.Sleep(50 * time.Microsecond)
  48                 atomic.StoreInt32(&done, 1)
  49                 for atomic.LoadInt32(&done) == 1 {
  50                         runtime.Gosched()
  51                 }
  52         }
  53 }