From f71fc8afd32eb4263dd0580dfd739555d9f47aff Mon Sep 17 00:00:00 2001
From: Robert Fratto <robertfratto@gmail.com>
Date: Mon, 10 Feb 2025 12:11:47 -0500
Subject: [PATCH] chore(dataobj): pool instances of dataobj encoders (#16166)

---
 pkg/dataobj/builder.go | 14 ++++++--------
 pkg/dataobj/pools.go   | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 pkg/dataobj/pools.go

diff --git a/pkg/dataobj/builder.go b/pkg/dataobj/builder.go
index fefe62cb1c..fa8f551956 100644
--- a/pkg/dataobj/builder.go
+++ b/pkg/dataobj/builder.go
@@ -110,8 +110,6 @@ type Builder struct {
 	logs    *logs.Logs
 
 	state builderState
-
-	encoder *encoding.Encoder
 }
 
 type builderState int
@@ -160,8 +158,6 @@ func NewBuilder(cfg BuilderConfig) (*Builder, error) {
 			BufferSize:   int(cfg.BufferSize),
 			SectionSize:  int(cfg.TargetSectionSize),
 		}),
-
-		encoder: encoding.NewEncoder(nil),
 	}, nil
 }
 
@@ -290,13 +286,15 @@ func (b *Builder) buildObject(output *bytes.Buffer) error {
 
 	initialBufferSize := output.Len()
 
-	b.encoder.Reset(output)
+	enc := encoderPool.Get().(*encoding.Encoder)
+	enc.Reset(output)
+	defer encoderPool.Put(enc)
 
-	if err := b.streams.EncodeTo(b.encoder); err != nil {
+	if err := b.streams.EncodeTo(enc); err != nil {
 		return fmt.Errorf("encoding streams: %w", err)
-	} else if err := b.logs.EncodeTo(b.encoder); err != nil {
+	} else if err := b.logs.EncodeTo(enc); err != nil {
 		return fmt.Errorf("encoding logs: %w", err)
-	} else if err := b.encoder.Flush(); err != nil {
+	} else if err := enc.Flush(); err != nil {
 		return fmt.Errorf("encoding object: %w", err)
 	}
 
diff --git a/pkg/dataobj/pools.go b/pkg/dataobj/pools.go
new file mode 100644
index 0000000000..1b614c4cd7
--- /dev/null
+++ b/pkg/dataobj/pools.go
@@ -0,0 +1,15 @@
+package dataobj
+
+import (
+	"sync"
+
+	"github.com/grafana/loki/v3/pkg/dataobj/internal/encoding"
+)
+
+// encoderPool holds a pool of [encoding.Encoder] instances. Callers must
+// always reset pooled encoders before use.
+var encoderPool = sync.Pool{
+	New: func() any {
+		return encoding.NewEncoder(nil)
+	},
+}