Switch to sync.Pool.

sync.Pool is after all faster than the home-made free list. Especially
under contention. To prove that, this commit also adds a benchmark for
concurrent fingerprint calculation.

Benchmark results:
(Run with -cpu=1,2,4. x-y -> x goroutines with GOMAXPROCS=y.)

benchmark                                     old ns/op     new ns/op     delta
BenchmarkMetricToFingerprintTripleConc4-4     320           138           -56.88%
BenchmarkMetricToFingerprintTripleConc8-4     314           141           -55.10%
BenchmarkMetricToFingerprintTripleConc4-2     344           264           -23.26%
BenchmarkMetricToFingerprintTripleConc2-4     331           256           -22.66%
BenchmarkMetricToFingerprintTripleConc8-2     338           263           -22.19%
BenchmarkMetricToFingerprintTripleConc1-4     599           505           -15.69%
BenchmarkMetricToFingerprintTripleConc4       553           493           -10.85%
BenchmarkMetricToFingerprintTripleConc2-2     327           292           -10.70%
BenchmarkMetricToFingerprintTripleConc8       554           496           -10.47%
BenchmarkMetricToFingerprintTripleConc2       555           501           -9.73%
BenchmarkMetricToFingerprintTripleConc1       554           509           -8.12%
BenchmarkMetricToFingerprintTripleConc1-2     551           513           -6.90%
This commit is contained in:
beorn7 2015-03-04 12:35:06 +01:00
parent 1002745d7b
commit cbe221c969
2 changed files with 44 additions and 9 deletions

View File

@ -17,6 +17,7 @@ import (
"bytes"
"hash"
"hash/fnv"
"sync"
)
// SeparatorByte is a byte that cannot occur in valid UTF-8 sequences and is
@ -28,7 +29,7 @@ var (
// cache the signature of an empty label set.
emptyLabelSignature = fnv.New64a().Sum64()
hashAndBufPool = make(chan *hashAndBuf, 1024)
hashAndBufPool sync.Pool
)
type hashAndBuf struct {
@ -37,19 +38,15 @@ type hashAndBuf struct {
}
func getHashAndBuf() *hashAndBuf {
select {
case hb := <-hashAndBufPool:
return hb
default:
hb := hashAndBufPool.Get()
if hb == nil {
return &hashAndBuf{h: fnv.New64a()}
}
return hb.(*hashAndBuf)
}
func putHashAndBuf(hb *hashAndBuf) {
select {
case hashAndBufPool <- hb:
default:
}
hashAndBufPool.Put(hb)
}
// LabelsToSignature returns a unique signature (i.e., fingerprint) for a given

View File

@ -15,6 +15,7 @@ package model
import (
"runtime"
"sync"
"testing"
)
@ -216,3 +217,40 @@ func TestEmptyLabelSignature(t *testing.T) {
t.Fatal("expected LabelsToSignature with empty labels not to perform allocations")
}
}
func benchmarkMetricToFingerprintConc(b *testing.B, m Metric, e Fingerprint, concLevel int) {
var start, end sync.WaitGroup
start.Add(1)
end.Add(concLevel)
for i := 0; i < concLevel; i++ {
go func() {
start.Wait()
for j := b.N / concLevel; j >= 0; j-- {
if a := metricToFingerprint(m); a != e {
b.Fatalf("expected signature of %d for %s, got %d", e, m, a)
}
}
end.Done()
}()
}
b.ResetTimer()
start.Done()
end.Wait()
}
func BenchmarkMetricToFingerprintTripleConc1(b *testing.B) {
benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 1)
}
func BenchmarkMetricToFingerprintTripleConc2(b *testing.B) {
benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 2)
}
func BenchmarkMetricToFingerprintTripleConc4(b *testing.B) {
benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 4)
}
func BenchmarkMetricToFingerprintTripleConc8(b *testing.B) {
benchmarkMetricToFingerprintConc(b, Metric{"first-label": "first-label-value", "second-label": "second-label-value", "third-label": "third-label-value"}, 15738406913934009676, 8)
}