Merge pull request #1934 from saschagrunert/optimize/json-buffer-pooling

Add buffer pooling for JSON operations

Author: k8s-ci-robot

cmd/crictl/bufferpool.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"bytes"
+	"sync"
+)
+
+// jsonBufferPool is a pool of bytes.Buffer instances used for JSON operations.
+// This reduces GC pressure by reusing buffers instead of allocating new ones
+// for each JSON indentation operation.
+var jsonBufferPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+// getJSONBuffer retrieves a buffer from the pool.
+// The caller must call putJSONBuffer when done to return it to the pool.
+func getJSONBuffer() *bytes.Buffer {
+	buf, ok := jsonBufferPool.Get().(*bytes.Buffer)
+	if !ok {
+		return new(bytes.Buffer)
+	}
+
+	return buf
+}
+
+// putJSONBuffer resets and returns a buffer to the pool.
+// This should be called with defer after getJSONBuffer.
+func putJSONBuffer(buf *bytes.Buffer) {
+	buf.Reset()
+	jsonBufferPool.Put(buf)
+}

cmd/crictl/util.go

@@ -17,7 +17,6 @@ limitations under the License.
 package main
 
 import (
-	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -421,8 +420,10 @@ func outputStatusData(statuses []statusData, format, tmplStr string) (err error)
 
 		fmt.Println(string(yamlInfo))
 	case outputTypeJSON:
-		var output bytes.Buffer
-		if err := json.Indent(&output, jsonResult, "", "  "); err != nil {
+		output := getJSONBuffer()
+		defer putJSONBuffer(output)
+
+		if err := json.Indent(output, jsonResult, "", "  "); err != nil {
 			return fmt.Errorf("indent JSON result: %w", err)
 		}
 
@@ -519,9 +520,10 @@ func marshalMapInOrder(m map[string]any, t any) (string, error) {
 
 	sb.WriteString("}")
 
-	var buf bytes.Buffer
+	buf := getJSONBuffer()
+	defer putJSONBuffer(buf)
 
-	if err := json.Indent(&buf, []byte(sb.String()), "", "  "); err != nil {
+	if err := json.Indent(buf, []byte(sb.String()), "", "  "); err != nil {
 		return "", err
 	}