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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
// Copyright 2020 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"
"runtime/metrics"
"sort"
"strings"
"testing"
"time"
"unsafe"
)
func prepareAllMetricsSamples() (map[string]metrics.Description, []metrics.Sample) {
all := metrics.All()
samples := make([]metrics.Sample, len(all))
descs := make(map[string]metrics.Description)
for i := range all {
samples[i].Name = all[i].Name
descs[all[i].Name] = all[i]
}
return descs, samples
}
func TestReadMetrics(t *testing.T) {
// Tests whether readMetrics produces values aligning
// with ReadMemStats while the world is stopped.
var mstats runtime.MemStats
_, samples := prepareAllMetricsSamples()
runtime.ReadMetricsSlow(&mstats, unsafe.Pointer(&samples[0]), len(samples), cap(samples))
checkUint64 := func(t *testing.T, m string, got, want uint64) {
t.Helper()
if got != want {
t.Errorf("metric %q: got %d, want %d", m, got, want)
}
}
// Check to make sure the values we read line up with other values we read.
for i := range samples {
switch name := samples[i].Name; name {
case "/memory/classes/heap/free:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapIdle-mstats.HeapReleased)
case "/memory/classes/heap/released:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapReleased)
case "/memory/classes/heap/objects:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapAlloc)
case "/memory/classes/heap/unused:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapInuse-mstats.HeapAlloc)
case "/memory/classes/heap/stacks:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.StackInuse)
case "/memory/classes/metadata/mcache/free:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.MCacheSys-mstats.MCacheInuse)
case "/memory/classes/metadata/mcache/inuse:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.MCacheInuse)
case "/memory/classes/metadata/mspan/free:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.MSpanSys-mstats.MSpanInuse)
case "/memory/classes/metadata/mspan/inuse:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.MSpanInuse)
case "/memory/classes/metadata/other:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.GCSys)
case "/memory/classes/os-stacks:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.StackSys-mstats.StackInuse)
case "/memory/classes/other:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.OtherSys)
case "/memory/classes/profiling/buckets:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.BuckHashSys)
case "/memory/classes/total:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.Sys)
case "/gc/heap/objects:objects":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapObjects)
case "/gc/heap/goal:bytes":
checkUint64(t, name, samples[i].Value.Uint64(), mstats.NextGC)
case "/gc/cycles/automatic:gc-cycles":
checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumGC-mstats.NumForcedGC))
case "/gc/cycles/forced:gc-cycles":
checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumForcedGC))
case "/gc/cycles/total:gc-cycles":
checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumGC))
}
}
}
func TestReadMetricsConsistency(t *testing.T) {
// Tests whether readMetrics produces consistent, sensible values.
// The values are read concurrently with the runtime doing other
// things (e.g. allocating) so what we read can't reasonably compared
// to runtime values.
// Run a few GC cycles to get some of the stats to be non-zero.
runtime.GC()
runtime.GC()
runtime.GC()
// Read all the supported metrics through the metrics package.
descs, samples := prepareAllMetricsSamples()
metrics.Read(samples)
// Check to make sure the values we read make sense.
var totalVirtual struct {
got, want uint64
}
var objects struct {
alloc, free *metrics.Float64Histogram
total uint64
}
var gc struct {
numGC uint64
pauses uint64
}
for i := range samples {
kind := samples[i].Value.Kind()
if want := descs[samples[i].Name].Kind; kind != want {
t.Errorf("supported metric %q has unexpected kind: got %d, want %d", samples[i].Name, kind, want)
continue
}
if samples[i].Name != "/memory/classes/total:bytes" && strings.HasPrefix(samples[i].Name, "/memory/classes") {
v := samples[i].Value.Uint64()
totalVirtual.want += v
// None of these stats should ever get this big.
// If they do, there's probably overflow involved,
// usually due to bad accounting.
if int64(v) < 0 {
t.Errorf("%q has high/negative value: %d", samples[i].Name, v)
}
}
switch samples[i].Name {
case "/memory/classes/total:bytes":
totalVirtual.got = samples[i].Value.Uint64()
case "/gc/heap/objects:objects":
objects.total = samples[i].Value.Uint64()
case "/gc/heap/allocs-by-size:objects":
objects.alloc = samples[i].Value.Float64Histogram()
case "/gc/heap/frees-by-size:objects":
objects.free = samples[i].Value.Float64Histogram()
case "/gc/cycles:gc-cycles":
gc.numGC = samples[i].Value.Uint64()
case "/gc/pauses:seconds":
h := samples[i].Value.Float64Histogram()
gc.pauses = 0
for i := range h.Counts {
gc.pauses += h.Counts[i]
}
case "/sched/goroutines:goroutines":
if samples[i].Value.Uint64() < 1 {
t.Error("number of goroutines is less than one")
}
}
}
if totalVirtual.got != totalVirtual.want {
t.Errorf(`"/memory/classes/total:bytes" does not match sum of /memory/classes/**: got %d, want %d`, totalVirtual.got, totalVirtual.want)
}
if len(objects.alloc.Buckets) != len(objects.free.Buckets) {
t.Error("allocs-by-size and frees-by-size buckets don't match in length")
} else if len(objects.alloc.Counts) != len(objects.free.Counts) {
t.Error("allocs-by-size and frees-by-size counts don't match in length")
} else {
for i := range objects.alloc.Buckets {
ba := objects.alloc.Buckets[i]
bf := objects.free.Buckets[i]
if ba != bf {
t.Errorf("bucket %d is different for alloc and free hists: %f != %f", i, ba, bf)
}
}
if !t.Failed() {
got, want := uint64(0), objects.total
for i := range objects.alloc.Counts {
if objects.alloc.Counts[i] < objects.free.Counts[i] {
t.Errorf("found more allocs than frees in object dist bucket %d", i)
continue
}
got += objects.alloc.Counts[i] - objects.free.Counts[i]
}
if got != want {
t.Errorf("object distribution counts don't match count of live objects: got %d, want %d", got, want)
}
}
}
// The current GC has at least 2 pauses per GC.
// Check to see if that value makes sense.
if gc.pauses < gc.numGC*2 {
t.Errorf("fewer pauses than expected: got %d, want at least %d", gc.pauses, gc.numGC*2)
}
}
func BenchmarkReadMetricsLatency(b *testing.B) {
stop := applyGCLoad(b)
// Spend this much time measuring latencies.
latencies := make([]time.Duration, 0, 1024)
_, samples := prepareAllMetricsSamples()
// Hit metrics.Read continuously and measure.
b.ResetTimer()
for i := 0; i < b.N; i++ {
start := time.Now()
metrics.Read(samples)
latencies = append(latencies, time.Now().Sub(start))
}
// Make sure to stop the timer before we wait! The load created above
// is very heavy-weight and not easy to stop, so we could end up
// confusing the benchmarking framework for small b.N.
b.StopTimer()
stop()
// Disable the default */op metrics.
// ns/op doesn't mean anything because it's an average, but we
// have a sleep in our b.N loop above which skews this significantly.
b.ReportMetric(0, "ns/op")
b.ReportMetric(0, "B/op")
b.ReportMetric(0, "allocs/op")
// Sort latencies then report percentiles.
sort.Slice(latencies, func(i, j int) bool {
return latencies[i] < latencies[j]
})
b.ReportMetric(float64(latencies[len(latencies)*50/100]), "p50-ns")
b.ReportMetric(float64(latencies[len(latencies)*90/100]), "p90-ns")
b.ReportMetric(float64(latencies[len(latencies)*99/100]), "p99-ns")
}
|
