1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime_test
import (
"runtime"
"sync/atomic"
"testing"
)
var stop = make(chan bool, 1)
func perpetuumMobile() {
select {
case <-stop:
default:
go perpetuumMobile()
}
}
func TestStopTheWorldDeadlock(t *testing.T) {
if testing.Short() {
t.Skip("skipping during short test")
}
maxprocs := runtime.GOMAXPROCS(3)
compl := make(chan bool, 2)
go func() {
for i := 0; i != 1000; i += 1 {
runtime.GC()
}
compl <- true
}()
go func() {
for i := 0; i != 1000; i += 1 {
runtime.GOMAXPROCS(3)
}
compl <- true
}()
go perpetuumMobile()
<-compl
<-compl
stop <- true
runtime.GOMAXPROCS(maxprocs)
}
func stackGrowthRecursive(i int) {
var pad [128]uint64
if i != 0 && pad[0] == 0 {
stackGrowthRecursive(i - 1)
}
}
func benchmarkStackGrowth(b *testing.B, rec int) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
stackGrowthRecursive(rec)
}
}
c <- true
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
func BenchmarkStackGrowth(b *testing.B) {
benchmarkStackGrowth(b, 10)
}
func BenchmarkStackGrowthDeep(b *testing.B) {
benchmarkStackGrowth(b, 1024)
}
func BenchmarkSyscall(b *testing.B) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
runtime.Entersyscall()
runtime.Exitsyscall()
}
}
c <- true
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
func BenchmarkSyscallWork(b *testing.B) {
const CallsPerSched = 1000
const LocalWork = 100
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
foo := 42
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
runtime.Entersyscall()
for i := 0; i < LocalWork; i++ {
foo *= 2
foo /= 2
}
runtime.Exitsyscall()
}
}
c <- foo == 42
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
func BenchmarkCreateGoroutines(b *testing.B) {
benchmarkCreateGoroutines(b, 1)
}
func BenchmarkCreateGoroutinesParallel(b *testing.B) {
benchmarkCreateGoroutines(b, runtime.GOMAXPROCS(-1))
}
func benchmarkCreateGoroutines(b *testing.B, procs int) {
c := make(chan bool)
var f func(n int)
f = func(n int) {
if n == 0 {
c <- true
return
}
go f(n - 1)
}
for i := 0; i < procs; i++ {
go f(b.N / procs)
}
for i := 0; i < procs; i++ {
<-c
}
}
|
