ddtrace/tracer: remove meta maps pool

Releasing the map after encoding the span for submission doesn't play well with our current codebase
DataDog · Aug 7, 2024 · 30d6cd8 · 30d6cd8
1 parent d091651
commit 30d6cd8
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Showing 4 changed files with 4 additions and 46 deletions.
diff --git a/ddtrace/tracer/span.go b/ddtrace/tracer/span.go
@@ -387,7 +387,7 @@ func takeStacktrace(n, skip uint) string {
 // setMeta sets a string tag. This method is not safe for concurrent use.
 func (s *span) setMeta(key, v string) {
 	if s.Meta == nil {
-		s.Meta = mmp.Get()
+		s.Meta = defaultMetaMap()
 	}
 	delete(s.Metrics, key)
 	switch key {

diff --git a/ddtrace/tracer/spantags.go b/ddtrace/tracer/spantags.go
@@ -4,40 +4,3 @@
 // Copyright 2024 Datadog, Inc.
 
 package tracer
-
-import "sync"
-
-type metaMapPool struct {
-	*sync.Pool
-}
-
-var mmp = &metaMapPool{
-	Pool: &sync.Pool{
-		New: func() any {
-			return defaultMetaMap()
-		},
-	},
-}
-
-func (p *metaMapPool) Get() map[string]string {
-	return p.Pool.Get().(map[string]string)
-}
-
-func (p *metaMapPool) Put(m map[string]string) {
-	if m == nil {
-		return
-	}
-	clear(m)
-	p.Pool.Put(m)
-}
-
-func releaseSpanMaps(spans []*span) {
-	for i := range spans {
-		releaseSpanMap(spans[i])
-	}
-}
-
-func releaseSpanMap(s *span) {
-	mmp.Put(s.Meta)
-	s.Meta = nil
-}
diff --git a/ddtrace/tracer/spantags_test.go b/ddtrace/tracer/spantags_test.go
@@ -22,8 +22,7 @@ func BenchmarkSpanLifecycle(b *testing.B) {
 		[]float64{8.75, 14.59, 22.8, 31.2, 39.1, 43.5, 54.3, 70.0},
 	)
 	b.Run("baseline/set tag", func(b *testing.B) {
-		span := &span{}
-		span.setMeta("key", "value")
+		span := newBasicSpan("benchmark")
 		if span.Meta == nil {
 			b.Fatal("expected span.Meta to be non-nil")
 		}
@@ -36,13 +35,12 @@ func BenchmarkSpanLifecycle(b *testing.B) {
 		// preallocate the spans
 		spans := make([]*span, b.N)
 		for i := 0; i < b.N; i++ {
-			spans[i] = &span{}
+			spans[i] = newBasicSpan("benchmark")
 		}
 		b.ResetTimer()
 		b.ReportMetric(1.0, "tags/op")
 		for i := 0; i < b.N; i++ {
 			spans[i].setMeta("key", "value")
-			releaseSpanMap(spans[i])
 		}
 	})
 	b.Run("with tags", func(b *testing.B) {
@@ -58,7 +56,7 @@ func BenchmarkSpanLifecycle(b *testing.B) {
 		}, b.N)
 		totalSpanTags := 0
 		for i := 0; i < b.N; i++ {
-			spans[i].span = &span{}
+			spans[i].span = newBasicSpan("benchmark")
 			spans[i].n = int(distribution.generate(r))
 			totalSpanTags += spans[i].n
 		}
@@ -69,7 +67,6 @@ func BenchmarkSpanLifecycle(b *testing.B) {
 			for j := 0; j < spans[i].n; j++ {
 				s.setMeta(tags[j], "value")
 			}
-			releaseSpanMap(s)
 		}
 	})
 }

diff --git a/ddtrace/tracer/tracer.go b/ddtrace/tracer/tracer.go
@@ -369,7 +369,6 @@ func (t *tracer) worker(tick <-chan time.Time) {
 			t.sampleChunk(trace)
 			if len(trace.spans) != 0 {
 				t.traceWriter.add(trace.spans)
-				releaseSpanMaps(trace.spans)
 			}
 		case <-tick:
 			t.statsd.Incr("datadog.tracer.flush_triggered", []string{"reason:scheduled"}, 1)
@@ -395,7 +394,6 @@ func (t *tracer) worker(tick <-chan time.Time) {
 					t.sampleChunk(trace)
 					if len(trace.spans) != 0 {
 						t.traceWriter.add(trace.spans)
-						releaseSpanMaps(trace.spans)
 					}
 				default:
 					break loop