client_golang/prometheus/go_collector_latest.go

569 lines
18 KiB
Go

// Copyright 2021 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build go1.17
// +build go1.17
package prometheus
import (
"math"
"runtime"
"runtime/metrics"
"strings"
"sync"
//nolint:staticcheck // Ignore SA1019. Need to keep deprecated package for compatibility.
"github.com/golang/protobuf/proto"
dto "github.com/prometheus/client_model/go"
"git.internal/re/client_golang/prometheus/internal"
)
const (
// constants for strings referenced more than once.
goGCHeapTinyAllocsObjects = "/gc/heap/tiny/allocs:objects"
goGCHeapAllocsObjects = "/gc/heap/allocs:objects"
goGCHeapFreesObjects = "/gc/heap/frees:objects"
goGCHeapFreesBytes = "/gc/heap/frees:bytes"
goGCHeapAllocsBytes = "/gc/heap/allocs:bytes"
goGCHeapObjects = "/gc/heap/objects:objects"
goGCHeapGoalBytes = "/gc/heap/goal:bytes"
goMemoryClassesTotalBytes = "/memory/classes/total:bytes"
goMemoryClassesHeapObjectsBytes = "/memory/classes/heap/objects:bytes"
goMemoryClassesHeapUnusedBytes = "/memory/classes/heap/unused:bytes"
goMemoryClassesHeapReleasedBytes = "/memory/classes/heap/released:bytes"
goMemoryClassesHeapFreeBytes = "/memory/classes/heap/free:bytes"
goMemoryClassesHeapStacksBytes = "/memory/classes/heap/stacks:bytes"
goMemoryClassesOSStacksBytes = "/memory/classes/os-stacks:bytes"
goMemoryClassesMetadataMSpanInuseBytes = "/memory/classes/metadata/mspan/inuse:bytes"
goMemoryClassesMetadataMSPanFreeBytes = "/memory/classes/metadata/mspan/free:bytes"
goMemoryClassesMetadataMCacheInuseBytes = "/memory/classes/metadata/mcache/inuse:bytes"
goMemoryClassesMetadataMCacheFreeBytes = "/memory/classes/metadata/mcache/free:bytes"
goMemoryClassesProfilingBucketsBytes = "/memory/classes/profiling/buckets:bytes"
goMemoryClassesMetadataOtherBytes = "/memory/classes/metadata/other:bytes"
goMemoryClassesOtherBytes = "/memory/classes/other:bytes"
)
// rmNamesForMemStatsMetrics represents runtime/metrics names required to populate goRuntimeMemStats from like logic.
var rmNamesForMemStatsMetrics = []string{
goGCHeapTinyAllocsObjects,
goGCHeapAllocsObjects,
goGCHeapFreesObjects,
goGCHeapAllocsBytes,
goGCHeapObjects,
goGCHeapGoalBytes,
goMemoryClassesTotalBytes,
goMemoryClassesHeapObjectsBytes,
goMemoryClassesHeapUnusedBytes,
goMemoryClassesHeapReleasedBytes,
goMemoryClassesHeapFreeBytes,
goMemoryClassesHeapStacksBytes,
goMemoryClassesOSStacksBytes,
goMemoryClassesMetadataMSpanInuseBytes,
goMemoryClassesMetadataMSPanFreeBytes,
goMemoryClassesMetadataMCacheInuseBytes,
goMemoryClassesMetadataMCacheFreeBytes,
goMemoryClassesProfilingBucketsBytes,
goMemoryClassesMetadataOtherBytes,
goMemoryClassesOtherBytes,
}
func bestEffortLookupRM(lookup []string) []metrics.Description {
ret := make([]metrics.Description, 0, len(lookup))
for _, rm := range metrics.All() {
for _, m := range lookup {
if m == rm.Name {
ret = append(ret, rm)
}
}
}
return ret
}
type goCollector struct {
base baseGoCollector
// mu protects updates to all fields ensuring a consistent
// snapshot is always produced by Collect.
mu sync.Mutex
// Contains all samples that has to retrieved from runtime/metrics (not all of them will be exposed).
sampleBuf []metrics.Sample
// sampleMap allows lookup for MemStats metrics and runtime/metrics histograms for exact sums.
sampleMap map[string]*metrics.Sample
// rmExposedMetrics represents all runtime/metrics package metrics
// that were configured to be exposed.
rmExposedMetrics []collectorMetric
rmExactSumMapForHist map[string]string
// With Go 1.17, the runtime/metrics package was introduced.
// From that point on, metric names produced by the runtime/metrics
// package could be generated from runtime/metrics names. However,
// these differ from the old names for the same values.
//
// This field exists to export the same values under the old names
// as well.
msMetrics memStatsMetrics
msMetricsEnabled bool
}
type rmMetricDesc struct {
metrics.Description
}
func matchRuntimeMetricsRules(rules []internal.GoCollectorRule) []rmMetricDesc {
var descs []rmMetricDesc
for _, d := range metrics.All() {
var (
deny = true
desc rmMetricDesc
)
for _, r := range rules {
if !r.Matcher.MatchString(d.Name) {
continue
}
deny = r.Deny
}
if deny {
continue
}
desc.Description = d
descs = append(descs, desc)
}
return descs
}
func defaultGoCollectorOptions() internal.GoCollectorOptions {
return internal.GoCollectorOptions{
RuntimeMetricSumForHist: map[string]string{
"/gc/heap/allocs-by-size:bytes": goGCHeapAllocsBytes,
"/gc/heap/frees-by-size:bytes": goGCHeapFreesBytes,
},
RuntimeMetricRules: []internal.GoCollectorRule{
//{Matcher: regexp.MustCompile("")},
},
}
}
// NewGoCollector is the obsolete version of collectors.NewGoCollector.
// See there for documentation.
//
// Deprecated: Use collectors.NewGoCollector instead.
func NewGoCollector(opts ...func(o *internal.GoCollectorOptions)) Collector {
opt := defaultGoCollectorOptions()
for _, o := range opts {
o(&opt)
}
exposedDescriptions := matchRuntimeMetricsRules(opt.RuntimeMetricRules)
// Collect all histogram samples so that we can get their buckets.
// The API guarantees that the buckets are always fixed for the lifetime
// of the process.
var histograms []metrics.Sample
for _, d := range exposedDescriptions {
if d.Kind == metrics.KindFloat64Histogram {
histograms = append(histograms, metrics.Sample{Name: d.Name})
}
}
if len(histograms) > 0 {
metrics.Read(histograms)
}
bucketsMap := make(map[string][]float64)
for i := range histograms {
bucketsMap[histograms[i].Name] = histograms[i].Value.Float64Histogram().Buckets
}
// Generate a collector for each exposed runtime/metrics metric.
metricSet := make([]collectorMetric, 0, len(exposedDescriptions))
// SampleBuf is used for reading from runtime/metrics.
// We are assuming the largest case to have stable pointers for sampleMap purposes.
sampleBuf := make([]metrics.Sample, 0, len(exposedDescriptions)+len(opt.RuntimeMetricSumForHist)+len(rmNamesForMemStatsMetrics))
sampleMap := make(map[string]*metrics.Sample, len(exposedDescriptions))
for _, d := range exposedDescriptions {
namespace, subsystem, name, ok := internal.RuntimeMetricsToProm(&d.Description)
if !ok {
// Just ignore this metric; we can't do anything with it here.
// If a user decides to use the latest version of Go, we don't want
// to fail here. This condition is tested in TestExpectedRuntimeMetrics.
continue
}
sampleBuf = append(sampleBuf, metrics.Sample{Name: d.Name})
sampleMap[d.Name] = &sampleBuf[len(sampleBuf)-1]
var m collectorMetric
if d.Kind == metrics.KindFloat64Histogram {
_, hasSum := opt.RuntimeMetricSumForHist[d.Name]
unit := d.Name[strings.IndexRune(d.Name, ':')+1:]
m = newBatchHistogram(
NewDesc(
BuildFQName(namespace, subsystem, name),
d.Description.Description,
nil,
nil,
),
internal.RuntimeMetricsBucketsForUnit(bucketsMap[d.Name], unit),
hasSum,
)
} else if d.Cumulative {
m = NewCounter(CounterOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: name,
Help: d.Description.Description,
},
)
} else {
m = NewGauge(GaugeOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: name,
Help: d.Description.Description,
})
}
metricSet = append(metricSet, m)
}
// Add exact sum metrics to sampleBuf if not added before.
for _, h := range histograms {
sumMetric, ok := opt.RuntimeMetricSumForHist[h.Name]
if !ok {
continue
}
if _, ok := sampleMap[sumMetric]; ok {
continue
}
sampleBuf = append(sampleBuf, metrics.Sample{Name: sumMetric})
sampleMap[sumMetric] = &sampleBuf[len(sampleBuf)-1]
}
var (
msMetrics memStatsMetrics
msDescriptions []metrics.Description
)
if !opt.DisableMemStatsLikeMetrics {
msMetrics = goRuntimeMemStats()
msDescriptions = bestEffortLookupRM(rmNamesForMemStatsMetrics)
// Check if metric was not exposed before and if not, add to sampleBuf.
for _, mdDesc := range msDescriptions {
if _, ok := sampleMap[mdDesc.Name]; ok {
continue
}
sampleBuf = append(sampleBuf, metrics.Sample{Name: mdDesc.Name})
sampleMap[mdDesc.Name] = &sampleBuf[len(sampleBuf)-1]
}
}
return &goCollector{
base: newBaseGoCollector(),
sampleBuf: sampleBuf,
sampleMap: sampleMap,
rmExposedMetrics: metricSet,
rmExactSumMapForHist: opt.RuntimeMetricSumForHist,
msMetrics: msMetrics,
msMetricsEnabled: !opt.DisableMemStatsLikeMetrics,
}
}
// Describe returns all descriptions of the collector.
func (c *goCollector) Describe(ch chan<- *Desc) {
c.base.Describe(ch)
for _, i := range c.msMetrics {
ch <- i.desc
}
for _, m := range c.rmExposedMetrics {
ch <- m.Desc()
}
}
// Collect returns the current state of all metrics of the collector.
func (c *goCollector) Collect(ch chan<- Metric) {
// Collect base non-memory metrics.
c.base.Collect(ch)
if len(c.sampleBuf) == 0 {
return
}
// Collect must be thread-safe, so prevent concurrent use of
// sampleBuf elements. Just read into sampleBuf but write all the data
// we get into our Metrics or MemStats.
//
// This lock also ensures that the Metrics we send out are all from
// the same updates, ensuring their mutual consistency insofar as
// is guaranteed by the runtime/metrics package.
//
// N.B. This locking is heavy-handed, but Collect is expected to be called
// relatively infrequently. Also the core operation here, metrics.Read,
// is fast (O(tens of microseconds)) so contention should certainly be
// low, though channel operations and any allocations may add to that.
c.mu.Lock()
defer c.mu.Unlock()
// Populate runtime/metrics sample buffer.
metrics.Read(c.sampleBuf)
// Collect all our runtime/metrics user chose to expose from sampleBuf (if any).
for i, metric := range c.rmExposedMetrics {
// We created samples for exposed metrics first in order, so indexes match.
sample := c.sampleBuf[i]
// N.B. switch on concrete type because it's significantly more efficient
// than checking for the Counter and Gauge interface implementations. In
// this case, we control all the types here.
switch m := metric.(type) {
case *counter:
// Guard against decreases. This should never happen, but a failure
// to do so will result in a panic, which is a harsh consequence for
// a metrics collection bug.
v0, v1 := m.get(), unwrapScalarRMValue(sample.Value)
if v1 > v0 {
m.Add(unwrapScalarRMValue(sample.Value) - m.get())
}
m.Collect(ch)
case *gauge:
m.Set(unwrapScalarRMValue(sample.Value))
m.Collect(ch)
case *batchHistogram:
m.update(sample.Value.Float64Histogram(), c.exactSumFor(sample.Name))
m.Collect(ch)
default:
panic("unexpected metric type")
}
}
if c.msMetricsEnabled {
// ms is a dummy MemStats that we populate ourselves so that we can
// populate the old metrics from it if goMemStatsCollection is enabled.
var ms runtime.MemStats
memStatsFromRM(&ms, c.sampleMap)
for _, i := range c.msMetrics {
ch <- MustNewConstMetric(i.desc, i.valType, i.eval(&ms))
}
}
}
// unwrapScalarRMValue unwraps a runtime/metrics value that is assumed
// to be scalar and returns the equivalent float64 value. Panics if the
// value is not scalar.
func unwrapScalarRMValue(v metrics.Value) float64 {
switch v.Kind() {
case metrics.KindUint64:
return float64(v.Uint64())
case metrics.KindFloat64:
return v.Float64()
case metrics.KindBad:
// Unsupported metric.
//
// This should never happen because we always populate our metric
// set from the runtime/metrics package.
panic("unexpected unsupported metric")
default:
// Unsupported metric kind.
//
// This should never happen because we check for this during initialization
// and flag and filter metrics whose kinds we don't understand.
panic("unexpected unsupported metric kind")
}
}
// exactSumFor takes a runtime/metrics metric name (that is assumed to
// be of kind KindFloat64Histogram) and returns its exact sum and whether
// its exact sum exists.
//
// The runtime/metrics API for histograms doesn't currently expose exact
// sums, but some of the other metrics are in fact exact sums of histograms.
func (c *goCollector) exactSumFor(rmName string) float64 {
sumName, ok := c.rmExactSumMapForHist[rmName]
if !ok {
return 0
}
s, ok := c.sampleMap[sumName]
if !ok {
return 0
}
return unwrapScalarRMValue(s.Value)
}
func memStatsFromRM(ms *runtime.MemStats, rm map[string]*metrics.Sample) {
lookupOrZero := func(name string) uint64 {
if s, ok := rm[name]; ok {
return s.Value.Uint64()
}
return 0
}
// Currently, MemStats adds tiny alloc count to both Mallocs AND Frees.
// The reason for this is because MemStats couldn't be extended at the time
// but there was a desire to have Mallocs at least be a little more representative,
// while having Mallocs - Frees still represent a live object count.
// Unfortunately, MemStats doesn't actually export a large allocation count,
// so it's impossible to pull this number out directly.
tinyAllocs := lookupOrZero(goGCHeapTinyAllocsObjects)
ms.Mallocs = lookupOrZero(goGCHeapAllocsObjects) + tinyAllocs
ms.Frees = lookupOrZero(goGCHeapFreesObjects) + tinyAllocs
ms.TotalAlloc = lookupOrZero(goGCHeapAllocsBytes)
ms.Sys = lookupOrZero(goMemoryClassesTotalBytes)
ms.Lookups = 0 // Already always zero.
ms.HeapAlloc = lookupOrZero(goMemoryClassesHeapObjectsBytes)
ms.Alloc = ms.HeapAlloc
ms.HeapInuse = ms.HeapAlloc + lookupOrZero(goMemoryClassesHeapUnusedBytes)
ms.HeapReleased = lookupOrZero(goMemoryClassesHeapReleasedBytes)
ms.HeapIdle = ms.HeapReleased + lookupOrZero(goMemoryClassesHeapFreeBytes)
ms.HeapSys = ms.HeapInuse + ms.HeapIdle
ms.HeapObjects = lookupOrZero(goGCHeapObjects)
ms.StackInuse = lookupOrZero(goMemoryClassesHeapStacksBytes)
ms.StackSys = ms.StackInuse + lookupOrZero(goMemoryClassesOSStacksBytes)
ms.MSpanInuse = lookupOrZero(goMemoryClassesMetadataMSpanInuseBytes)
ms.MSpanSys = ms.MSpanInuse + lookupOrZero(goMemoryClassesMetadataMSPanFreeBytes)
ms.MCacheInuse = lookupOrZero(goMemoryClassesMetadataMCacheInuseBytes)
ms.MCacheSys = ms.MCacheInuse + lookupOrZero(goMemoryClassesMetadataMCacheFreeBytes)
ms.BuckHashSys = lookupOrZero(goMemoryClassesProfilingBucketsBytes)
ms.GCSys = lookupOrZero(goMemoryClassesMetadataOtherBytes)
ms.OtherSys = lookupOrZero(goMemoryClassesOtherBytes)
ms.NextGC = lookupOrZero(goGCHeapGoalBytes)
// N.B. GCCPUFraction is intentionally omitted. This metric is not useful,
// and often misleading due to the fact that it's an average over the lifetime
// of the process.
// See https://git.internal/re/client_golang/issues/842#issuecomment-861812034
// for more details.
ms.GCCPUFraction = 0
}
// batchHistogram is a mutable histogram that is updated
// in batches.
type batchHistogram struct {
selfCollector
// Static fields updated only once.
desc *Desc
hasSum bool
// Because this histogram operates in batches, it just uses a
// single mutex for everything. updates are always serialized
// but Write calls may operate concurrently with updates.
// Contention between these two sources should be rare.
mu sync.Mutex
buckets []float64 // Inclusive lower bounds, like runtime/metrics.
counts []uint64
sum float64 // Used if hasSum is true.
}
// newBatchHistogram creates a new batch histogram value with the given
// Desc, buckets, and whether or not it has an exact sum available.
//
// buckets must always be from the runtime/metrics package, following
// the same conventions.
func newBatchHistogram(desc *Desc, buckets []float64, hasSum bool) *batchHistogram {
// We need to remove -Inf values. runtime/metrics keeps them around.
// But -Inf bucket should not be allowed for prometheus histograms.
if buckets[0] == math.Inf(-1) {
buckets = buckets[1:]
}
h := &batchHistogram{
desc: desc,
buckets: buckets,
// Because buckets follows runtime/metrics conventions, there's
// 1 more value in the buckets list than there are buckets represented,
// because in runtime/metrics, the bucket values represent *boundaries*,
// and non-Inf boundaries are inclusive lower bounds for that bucket.
counts: make([]uint64, len(buckets)-1),
hasSum: hasSum,
}
h.init(h)
return h
}
// update updates the batchHistogram from a runtime/metrics histogram.
//
// sum must be provided if the batchHistogram was created to have an exact sum.
// h.buckets must be a strict subset of his.Buckets.
func (h *batchHistogram) update(his *metrics.Float64Histogram, sum float64) {
counts, buckets := his.Counts, his.Buckets
h.mu.Lock()
defer h.mu.Unlock()
// Clear buckets.
for i := range h.counts {
h.counts[i] = 0
}
// Copy and reduce buckets.
var j int
for i, count := range counts {
h.counts[j] += count
if buckets[i+1] == h.buckets[j+1] {
j++
}
}
if h.hasSum {
h.sum = sum
}
}
func (h *batchHistogram) Desc() *Desc {
return h.desc
}
func (h *batchHistogram) Write(out *dto.Metric) error {
h.mu.Lock()
defer h.mu.Unlock()
sum := float64(0)
if h.hasSum {
sum = h.sum
}
dtoBuckets := make([]*dto.Bucket, 0, len(h.counts))
totalCount := uint64(0)
for i, count := range h.counts {
totalCount += count
if !h.hasSum {
if count != 0 {
// N.B. This computed sum is an underestimate.
sum += h.buckets[i] * float64(count)
}
}
// Skip the +Inf bucket, but only for the bucket list.
// It must still count for sum and totalCount.
if math.IsInf(h.buckets[i+1], 1) {
break
}
// Float64Histogram's upper bound is exclusive, so make it inclusive
// by obtaining the next float64 value down, in order.
upperBound := math.Nextafter(h.buckets[i+1], h.buckets[i])
dtoBuckets = append(dtoBuckets, &dto.Bucket{
CumulativeCount: proto.Uint64(totalCount),
UpperBound: proto.Float64(upperBound),
})
}
out.Histogram = &dto.Histogram{
Bucket: dtoBuckets,
SampleCount: proto.Uint64(totalCount),
SampleSum: proto.Float64(sum),
}
return nil
}