go-pulse/metrics/exp/exp.go
turboboost55 7dc100714d
metrics: add cpu counters (#26796)
This PR adds counter metrics for the CPU system and the Geth process.
Currently the only metrics available for these items are gauges. Gauges are
fine when the consumer scrapes metrics data at the same interval as Geth
produces new values (every 3 seconds), but it is likely that most consumers
will not scrape that often. Intervals of 10, 15, or maybe even 30 seconds
are probably more common.

So the problem is, how does the consumer estimate what the CPU was doing in
between scrapes. With a counter, it's easy ... you just subtract two
successive values and divide by the time to get a nice, accurate average.
But with a gauge, you can't do that. A gauge reading is an instantaneous
picture of what was happening at that moment, but it gives you no idea
about what was going on between scrapes. Taking an average of values is
meaningless.
2023-03-23 14:13:50 +01:00

194 lines
6.0 KiB
Go

// Hook go-metrics into expvar
// on any /debug/metrics request, load all vars from the registry into expvar, and execute regular expvar handler
package exp
import (
"expvar"
"fmt"
"net/http"
"sync"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/ethereum/go-ethereum/metrics/prometheus"
)
type exp struct {
expvarLock sync.Mutex // expvar panics if you try to register the same var twice, so we must probe it safely
registry metrics.Registry
}
func (exp *exp) expHandler(w http.ResponseWriter, r *http.Request) {
// load our variables into expvar
exp.syncToExpvar()
// now just run the official expvar handler code (which is not publicly callable, so pasted inline)
w.Header().Set("Content-Type", "application/json; charset=utf-8")
fmt.Fprintf(w, "{\n")
first := true
expvar.Do(func(kv expvar.KeyValue) {
if !first {
fmt.Fprintf(w, ",\n")
}
first = false
fmt.Fprintf(w, "%q: %s", kv.Key, kv.Value)
})
fmt.Fprintf(w, "\n}\n")
}
// Exp will register an expvar powered metrics handler with http.DefaultServeMux on "/debug/vars"
func Exp(r metrics.Registry) {
h := ExpHandler(r)
// this would cause a panic:
// panic: http: multiple registrations for /debug/vars
// http.HandleFunc("/debug/vars", e.expHandler)
// haven't found an elegant way, so just use a different endpoint
http.Handle("/debug/metrics", h)
http.Handle("/debug/metrics/prometheus", prometheus.Handler(r))
}
// ExpHandler will return an expvar powered metrics handler.
func ExpHandler(r metrics.Registry) http.Handler {
e := exp{sync.Mutex{}, r}
return http.HandlerFunc(e.expHandler)
}
// Setup starts a dedicated metrics server at the given address.
// This function enables metrics reporting separate from pprof.
func Setup(address string) {
m := http.NewServeMux()
m.Handle("/debug/metrics", ExpHandler(metrics.DefaultRegistry))
m.Handle("/debug/metrics/prometheus", prometheus.Handler(metrics.DefaultRegistry))
log.Info("Starting metrics server", "addr", fmt.Sprintf("http://%s/debug/metrics", address))
go func() {
if err := http.ListenAndServe(address, m); err != nil {
log.Error("Failure in running metrics server", "err", err)
}
}()
}
func (exp *exp) getInt(name string) *expvar.Int {
var v *expvar.Int
exp.expvarLock.Lock()
p := expvar.Get(name)
if p != nil {
v = p.(*expvar.Int)
} else {
v = new(expvar.Int)
expvar.Publish(name, v)
}
exp.expvarLock.Unlock()
return v
}
func (exp *exp) getFloat(name string) *expvar.Float {
var v *expvar.Float
exp.expvarLock.Lock()
p := expvar.Get(name)
if p != nil {
v = p.(*expvar.Float)
} else {
v = new(expvar.Float)
expvar.Publish(name, v)
}
exp.expvarLock.Unlock()
return v
}
func (exp *exp) publishCounter(name string, metric metrics.Counter) {
v := exp.getInt(name)
v.Set(metric.Count())
}
func (exp *exp) publishCounterFloat64(name string, metric metrics.CounterFloat64) {
v := exp.getFloat(name)
v.Set(metric.Count())
}
func (exp *exp) publishGauge(name string, metric metrics.Gauge) {
v := exp.getInt(name)
v.Set(metric.Value())
}
func (exp *exp) publishGaugeFloat64(name string, metric metrics.GaugeFloat64) {
exp.getFloat(name).Set(metric.Value())
}
func (exp *exp) publishHistogram(name string, metric metrics.Histogram) {
h := metric.Snapshot()
ps := h.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999})
exp.getInt(name + ".count").Set(h.Count())
exp.getFloat(name + ".min").Set(float64(h.Min()))
exp.getFloat(name + ".max").Set(float64(h.Max()))
exp.getFloat(name + ".mean").Set(h.Mean())
exp.getFloat(name + ".std-dev").Set(h.StdDev())
exp.getFloat(name + ".50-percentile").Set(ps[0])
exp.getFloat(name + ".75-percentile").Set(ps[1])
exp.getFloat(name + ".95-percentile").Set(ps[2])
exp.getFloat(name + ".99-percentile").Set(ps[3])
exp.getFloat(name + ".999-percentile").Set(ps[4])
}
func (exp *exp) publishMeter(name string, metric metrics.Meter) {
m := metric.Snapshot()
exp.getInt(name + ".count").Set(m.Count())
exp.getFloat(name + ".one-minute").Set(m.Rate1())
exp.getFloat(name + ".five-minute").Set(m.Rate5())
exp.getFloat(name + ".fifteen-minute").Set(m.Rate15())
exp.getFloat(name + ".mean").Set(m.RateMean())
}
func (exp *exp) publishTimer(name string, metric metrics.Timer) {
t := metric.Snapshot()
ps := t.Percentiles([]float64{0.5, 0.75, 0.95, 0.99, 0.999})
exp.getInt(name + ".count").Set(t.Count())
exp.getFloat(name + ".min").Set(float64(t.Min()))
exp.getFloat(name + ".max").Set(float64(t.Max()))
exp.getFloat(name + ".mean").Set(t.Mean())
exp.getFloat(name + ".std-dev").Set(t.StdDev())
exp.getFloat(name + ".50-percentile").Set(ps[0])
exp.getFloat(name + ".75-percentile").Set(ps[1])
exp.getFloat(name + ".95-percentile").Set(ps[2])
exp.getFloat(name + ".99-percentile").Set(ps[3])
exp.getFloat(name + ".999-percentile").Set(ps[4])
exp.getFloat(name + ".one-minute").Set(t.Rate1())
exp.getFloat(name + ".five-minute").Set(t.Rate5())
exp.getFloat(name + ".fifteen-minute").Set(t.Rate15())
exp.getFloat(name + ".mean-rate").Set(t.RateMean())
}
func (exp *exp) publishResettingTimer(name string, metric metrics.ResettingTimer) {
t := metric.Snapshot()
ps := t.Percentiles([]float64{50, 75, 95, 99})
exp.getInt(name + ".count").Set(int64(len(t.Values())))
exp.getFloat(name + ".mean").Set(t.Mean())
exp.getInt(name + ".50-percentile").Set(ps[0])
exp.getInt(name + ".75-percentile").Set(ps[1])
exp.getInt(name + ".95-percentile").Set(ps[2])
exp.getInt(name + ".99-percentile").Set(ps[3])
}
func (exp *exp) syncToExpvar() {
exp.registry.Each(func(name string, i interface{}) {
switch i := i.(type) {
case metrics.Counter:
exp.publishCounter(name, i)
case metrics.CounterFloat64:
exp.publishCounterFloat64(name, i)
case metrics.Gauge:
exp.publishGauge(name, i)
case metrics.GaugeFloat64:
exp.publishGaugeFloat64(name, i)
case metrics.Histogram:
exp.publishHistogram(name, i)
case metrics.Meter:
exp.publishMeter(name, i)
case metrics.Timer:
exp.publishTimer(name, i)
case metrics.ResettingTimer:
exp.publishResettingTimer(name, i)
default:
panic(fmt.Sprintf("unsupported type for '%s': %T", name, i))
}
})
}