sdk/trace: use slices.Grow() to avoid excessive runtime.growslice() (#4818)

* sdk/trace: use slices.Grow() to avoid excessive runtime.growslice()

* go1.20 compat

* update go.mod/sum

* Update CHANGELOG.md

* Revert "update go.mod/sum"

This reverts commit 1e4fcfa86c.

* inline slices.Grow as ensureAttributesCapacity

* fix comment

* add bench

* fix inlining

* Apply suggestions from code review

Co-authored-by: Robert Pająk <pellared@hotmail.com>
Co-authored-by: Damien Mathieu <42@dmathieu.com>

* add ReportAllocs

* add benchmark variations with lower limit

* bugfix: we always want to set cap, just the value is a min()

* lint

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>
Co-authored-by: Damien Mathieu <42@dmathieu.com>

sdk/trace/span_test.go

@@ -16,6 +16,7 @@ package trace
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"testing"
 
@@ -243,3 +244,31 @@ func TestTruncateAttr(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkRecordingSpanSetAttributes(b *testing.B) {
+	var attrs []attribute.KeyValue
+	for i := 0; i < 100; i++ {
+		attr := attribute.String(fmt.Sprintf("hello.attrib%d", i), fmt.Sprintf("goodbye.attrib%d", i))
+		attrs = append(attrs, attr)
+	}
+
+	ctx := context.Background()
+	for _, limit := range []bool{false, true} {
+		b.Run(fmt.Sprintf("WithLimit/%t", limit), func(b *testing.B) {
+			b.ReportAllocs()
+			sl := NewSpanLimits()
+			if limit {
+				sl.AttributeCountLimit = 50
+			}
+			tp := NewTracerProvider(WithSampler(AlwaysSample()), WithSpanLimits(sl))
+			tracer := tp.Tracer("tracer")
+
+			b.ResetTimer()
+			for n := 0; n < b.N; n++ {
+				_, span := tracer.Start(ctx, "span")
+				span.SetAttributes(attrs...)
+				span.End()
+			}
+		})
+	}
+}