Simple benchmark for three logging packages.

logfmt-bench_test.go

package main

import (
	"io/ioutil"
	"testing"

	"github.com/Sirupsen/logrus"
	"github.com/go-kit/kit/log"
	"gopkg.in/inconshreveable/log15.v2"
)

func BenchmarkGokitLogfmt(b *testing.B) {
	lg := log.NewLogfmtLogger(ioutil.Discard)
	for i := 0; i < b.N; i++ {
		lg.Log("lvl", "info", "msg", "test message", "k1", "v1", "k2", "v2", "k3", "v3")
	}
}

func BenchmarkLog15Logfmt(b *testing.B) {
	lg := log15.New()
	lg.SetHandler(log15.StreamHandler(ioutil.Discard, log15.LogfmtFormat()))

	for i := 0; i < b.N; i++ {
		lg.Info("test message", "k1", "v1", "k2", "v2", "k3", "v3")
	}
}

func BenchmarkLogrusLogfmt(b *testing.B) {
	lg := logrus.New()
	lg.Out = ioutil.Discard

	for i := 0; i < b.N; i++ {
		lg.WithFields(logrus.Fields{
			"k1": "v1", "k2": "v2", "k3": "v3",
		}).Info("test message")
	}
}

Another performance improvement in GokitLogfmt: Less memory allocation when handling values that require quoting.

name            time/op
GokitLogfmt-4   3.41µs ± 3%
Log15Logfmt-4   18.4µs ± 4%
LogrusLogfmt-4  12.8µs ± 1%

name            alloc/op
GokitLogfmt-4     320B ± 0%
Log15Logfmt-4   1.96kB ± 0%
LogrusLogfmt-4  1.62kB ± 0%

name            allocs/op
GokitLogfmt-4     11.0 ± 0%
Log15Logfmt-4     45.0 ± 0%
LogrusLogfmt-4    27.0 ± 0%