Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 1 | // Copyright 2011 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package sync_test |
| 6 | |
| 7 | import ( |
| 8 | . "sync" |
| 9 | "sync/atomic" |
| 10 | "testing" |
| 11 | ) |
| 12 | |
| 13 | func testWaitGroup(t *testing.T, wg1 *WaitGroup, wg2 *WaitGroup) { |
| 14 | n := 16 |
| 15 | wg1.Add(n) |
| 16 | wg2.Add(n) |
| 17 | exited := make(chan bool, n) |
| 18 | for i := 0; i != n; i++ { |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 19 | go func() { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 20 | wg1.Done() |
| 21 | wg2.Wait() |
| 22 | exited <- true |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 23 | }() |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 24 | } |
| 25 | wg1.Wait() |
| 26 | for i := 0; i != n; i++ { |
| 27 | select { |
| 28 | case <-exited: |
| 29 | t.Fatal("WaitGroup released group too soon") |
| 30 | default: |
| 31 | } |
| 32 | wg2.Done() |
| 33 | } |
| 34 | for i := 0; i != n; i++ { |
| 35 | <-exited // Will block if barrier fails to unlock someone. |
| 36 | } |
| 37 | } |
| 38 | |
| 39 | func TestWaitGroup(t *testing.T) { |
| 40 | wg1 := &WaitGroup{} |
| 41 | wg2 := &WaitGroup{} |
| 42 | |
| 43 | // Run the same test a few times to ensure barrier is in a proper state. |
| 44 | for i := 0; i != 8; i++ { |
| 45 | testWaitGroup(t, wg1, wg2) |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | func TestWaitGroupMisuse(t *testing.T) { |
| 50 | defer func() { |
| 51 | err := recover() |
| 52 | if err != "sync: negative WaitGroup counter" { |
| 53 | t.Fatalf("Unexpected panic: %#v", err) |
| 54 | } |
| 55 | }() |
| 56 | wg := &WaitGroup{} |
| 57 | wg.Add(1) |
| 58 | wg.Done() |
| 59 | wg.Done() |
| 60 | t.Fatal("Should panic") |
| 61 | } |
| 62 | |
| 63 | func TestWaitGroupRace(t *testing.T) { |
| 64 | // Run this test for about 1ms. |
| 65 | for i := 0; i < 1000; i++ { |
| 66 | wg := &WaitGroup{} |
| 67 | n := new(int32) |
| 68 | // spawn goroutine 1 |
| 69 | wg.Add(1) |
| 70 | go func() { |
| 71 | atomic.AddInt32(n, 1) |
| 72 | wg.Done() |
| 73 | }() |
| 74 | // spawn goroutine 2 |
| 75 | wg.Add(1) |
| 76 | go func() { |
| 77 | atomic.AddInt32(n, 1) |
| 78 | wg.Done() |
| 79 | }() |
| 80 | // Wait for goroutine 1 and 2 |
| 81 | wg.Wait() |
| 82 | if atomic.LoadInt32(n) != 2 { |
| 83 | t.Fatal("Spurious wakeup from Wait") |
| 84 | } |
| 85 | } |
| 86 | } |
| 87 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 88 | func TestWaitGroupAlign(t *testing.T) { |
| 89 | type X struct { |
| 90 | x byte |
| 91 | wg WaitGroup |
| 92 | } |
| 93 | var x X |
| 94 | x.wg.Add(1) |
| 95 | go func(x *X) { |
| 96 | x.wg.Done() |
| 97 | }(&x) |
| 98 | x.wg.Wait() |
| 99 | } |
| 100 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 101 | func BenchmarkWaitGroupUncontended(b *testing.B) { |
| 102 | type PaddedWaitGroup struct { |
| 103 | WaitGroup |
| 104 | pad [128]uint8 |
| 105 | } |
| 106 | b.RunParallel(func(pb *testing.PB) { |
| 107 | var wg PaddedWaitGroup |
| 108 | for pb.Next() { |
| 109 | wg.Add(1) |
| 110 | wg.Done() |
| 111 | wg.Wait() |
| 112 | } |
| 113 | }) |
| 114 | } |
| 115 | |
| 116 | func benchmarkWaitGroupAddDone(b *testing.B, localWork int) { |
| 117 | var wg WaitGroup |
| 118 | b.RunParallel(func(pb *testing.PB) { |
| 119 | foo := 0 |
| 120 | for pb.Next() { |
| 121 | wg.Add(1) |
| 122 | for i := 0; i < localWork; i++ { |
| 123 | foo *= 2 |
| 124 | foo /= 2 |
| 125 | } |
| 126 | wg.Done() |
| 127 | } |
| 128 | _ = foo |
| 129 | }) |
| 130 | } |
| 131 | |
| 132 | func BenchmarkWaitGroupAddDone(b *testing.B) { |
| 133 | benchmarkWaitGroupAddDone(b, 0) |
| 134 | } |
| 135 | |
| 136 | func BenchmarkWaitGroupAddDoneWork(b *testing.B) { |
| 137 | benchmarkWaitGroupAddDone(b, 100) |
| 138 | } |
| 139 | |
| 140 | func benchmarkWaitGroupWait(b *testing.B, localWork int) { |
| 141 | var wg WaitGroup |
| 142 | b.RunParallel(func(pb *testing.PB) { |
| 143 | foo := 0 |
| 144 | for pb.Next() { |
| 145 | wg.Wait() |
| 146 | for i := 0; i < localWork; i++ { |
| 147 | foo *= 2 |
| 148 | foo /= 2 |
| 149 | } |
| 150 | } |
| 151 | _ = foo |
| 152 | }) |
| 153 | } |
| 154 | |
| 155 | func BenchmarkWaitGroupWait(b *testing.B) { |
| 156 | benchmarkWaitGroupWait(b, 0) |
| 157 | } |
| 158 | |
| 159 | func BenchmarkWaitGroupWaitWork(b *testing.B) { |
| 160 | benchmarkWaitGroupWait(b, 100) |
| 161 | } |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 162 | |
| 163 | func BenchmarkWaitGroupActuallyWait(b *testing.B) { |
| 164 | b.ReportAllocs() |
| 165 | b.RunParallel(func(pb *testing.PB) { |
| 166 | for pb.Next() { |
| 167 | var wg WaitGroup |
| 168 | wg.Add(1) |
| 169 | go func() { |
| 170 | wg.Done() |
| 171 | }() |
| 172 | wg.Wait() |
| 173 | } |
| 174 | }) |
| 175 | } |