If we want to push this to 1.0 (#38), we really need to make some intentional decisions about performance. The API as it stands was designed largely without considering performance, and (surprise!) it shows.

glogr_benchmark_test.go:

package bench

import (
	"flag"
	"os"
	"testing"

	"github.com/go-logr/glogr"
	"github.com/go-logr/logr"
	"github.com/golang/glog"
)

func init() {
	flag.Set("v", "1")
	flag.Set("logtostderr", "true")
	os.Stderr, _ = os.Open("/dev/null")
}

func BenchmarkGlogInfoOneArg(b *testing.B) {
	for i := 0; i < b.N; i++ {
		glog.Infof("this is a %s", "string")
	}
}

func BenchmarkGlogrInfoOneArg(b *testing.B) {
	var log logr.Logger = glogr.New()

	for i := 0; i < b.N; i++ {
		log.Info("this is", "a", "string")
	}
}

func BenchmarkGlogInfoSeveralArgs(b *testing.B) {
	for i := 0; i < b.N; i++ {
		glog.Infof("multi: bool %t, string %s, int %d, float %f, struct %v",
			true, "str", 42, 3.14, struct{ X, Y int }{93, 76})
	}
}

func BenchmarkGlogrInfoSeveralArgs(b *testing.B) {
	var log logr.Logger = glogr.New()

	for i := 0; i < b.N; i++ {
		log.Info("multi",
			"bool", true, "string", "str", "int", 42,
			"float", 3.14, "struct", struct{ X, Y int }{93, 76})
	}
}

func BenchmarkGlogInfoV0(b *testing.B) {
	for i := 0; i < b.N; i++ {
		glog.V(0).Infof("multi: bool %t, string %s, int %d, float %f, struct %v",
			true, "str", 42, 3.14, struct{ X, Y int }{93, 76})
	}
}

func BenchmarkGlogrInfoV0(b *testing.B) {
	var log logr.Logger = glogr.New()

	for i := 0; i < b.N; i++ {
		log.V(0).Info("multi",
			"bool", true, "string", "str", "int", 42,
			"float", 3.14, "struct", struct{ X, Y int }{93, 76})
	}
}

func BenchmarkGlogInfoV9(b *testing.B) {
	for i := 0; i < b.N; i++ {
		glog.V(9).Infof("multi: bool %t, string %s, int %d, float %f, struct %v",
			true, "str", 42, 3.14, struct{ X, Y int }{93, 76})
	}
}

func BenchmarkGlogrInfoV9(b *testing.B) {
	var log logr.Logger = glogr.New()

	for i := 0; i < b.N; i++ {
		log.V(9).Info("multi",
			"bool", true, "string", "str", "int", 42,
			"float", 3.14, "struct", struct{ X, Y int }{93, 76})
	}
}

Running this:

goos: linux
goarch: amd64
pkg: github.com/go-logr/glogr/bench
cpu: Intel(R) Xeon(R) W-2135 CPU @ 3.70GHz
BenchmarkGlogInfoOneArg-6         	  713682	      1675 ns/op
BenchmarkGlogrInfoOneArg-6        	  251154	      4761 ns/op
BenchmarkGlogInfoSeveralArgs-6    	  527288	      2285 ns/op
BenchmarkGlogrInfoSeveralArgs-6   	  167934	      7114 ns/op
BenchmarkGlogInfoV0-6             	  529798	      2286 ns/op
BenchmarkGlogrInfoV0-6            	  164413	      7293 ns/op
BenchmarkGlogInfoV9-6             	46018132	        25.70 ns/op
BenchmarkGlogrInfoV9-6            	 8412883	       142.2 ns/op

So it's notably slower. All of the variadic args escape to the heap, including the string keys (which regular glog does not suffer). But doesn't account for enough.

V() calls that are not taken also expand all their variadic args used.

Some of this is attributable to glogr being very dumb and wasteful (clone() on every call) but it's not clear how much. Before we call it 1.0 we need to do some homework.

Hmm, I think a big part of this is the benchmark benefitting from optimizations that probably are not realistic in the wild. I'll look into it more later