(kafka) branch trunk updated: MINOR: Add DCL to improve performance (#22098)

[chia7712]

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chia7712 pushed a commit to branch trunk
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/trunk by this push:
     new 282eef9d050 MINOR: Add DCL to improve performance (#22098)
282eef9d050 is described below

commit 282eef9d050901dddae06ba8a925b05ab755dfd9
Author: Bolin Lin <linbolin1...@gmail.com>
AuthorDate: Mon Apr 20 10:02:29 2026 -0400

    MINOR: Add DCL to improve performance (#22098)
    
    Synchronized method will cause the process lock here every time, it
    would be better to lock when we  actually need to create the meter,
    otherwise we can just return the  existed value.
    
    Reviewers: Ken Huang <s7133...@gmail.com>, Chia-Ping Tsai
     <chia7...@gmail.com>
---
 .../org/apache/kafka/common/metrics/Metrics.java   | 27 +++++++++++++---------
 .../kafka/server/util/timer/TimingWheel.java       | 20 +++++++++-------
 2 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java 
b/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
index 83a8f50cca0..8cbd9996ed4 100644
--- a/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
+++ b/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
@@ -369,7 +369,7 @@ public final class Metrics implements Closeable {
      * @param parents The parent sensors
      * @return The sensor that is created
      */
-    public synchronized Sensor sensor(String name, MetricConfig config, 
Sensor... parents) {
+    public Sensor sensor(String name, MetricConfig config, Sensor... parents) {
         return this.sensor(name, config, Sensor.RecordingLevel.INFO, parents);
     }
 
@@ -383,7 +383,7 @@ public final class Metrics implements Closeable {
      * @param parents The parent sensors
      * @return The sensor that is created
      */
-    public synchronized Sensor sensor(String name, MetricConfig config, 
Sensor.RecordingLevel recordingLevel, Sensor... parents) {
+    public Sensor sensor(String name, MetricConfig config, 
Sensor.RecordingLevel recordingLevel, Sensor... parents) {
         return sensor(name, config, Long.MAX_VALUE, recordingLevel, parents);
     }
 
@@ -398,18 +398,23 @@ public final class Metrics implements Closeable {
      * @param recordingLevel The recording level.
      * @return The sensor that is created
      */
-    public synchronized Sensor sensor(String name, MetricConfig config, long 
inactiveSensorExpirationTimeSeconds, Sensor.RecordingLevel recordingLevel, 
Sensor... parents) {
+    public Sensor sensor(String name, MetricConfig config, long 
inactiveSensorExpirationTimeSeconds, Sensor.RecordingLevel recordingLevel, 
Sensor... parents) {
         Sensor s = getSensor(name);
         if (s == null) {
-            s = new Sensor(this, name, parents, config == null ? this.config : 
config, time, inactiveSensorExpirationTimeSeconds, recordingLevel);
-            this.sensors.put(name, s);
-            if (parents != null) {
-                for (Sensor parent : parents) {
-                    List<Sensor> children = 
childrenSensors.computeIfAbsent(parent, k -> new ArrayList<>());
-                    children.add(s);
+            synchronized (this) {
+                s = getSensor(name);
+                if (s == null) {
+                    s = new Sensor(this, name, parents, config == null ? 
this.config : config, time, inactiveSensorExpirationTimeSeconds, 
recordingLevel);
+                    this.sensors.put(name, s);
+                    if (parents != null) {
+                        for (Sensor parent : parents) {
+                            List<Sensor> children = 
childrenSensors.computeIfAbsent(parent, k -> new ArrayList<>());
+                            children.add(s);
+                        }
+                    }
+                    log.trace("Added sensor with name {}", name);
                 }
             }
-            log.trace("Added sensor with name {}", name);
         }
         return s;
     }
@@ -424,7 +429,7 @@ public final class Metrics implements Closeable {
      * @param parents The parent sensors
      * @return The sensor that is created
      */
-    public synchronized Sensor sensor(String name, MetricConfig config, long 
inactiveSensorExpirationTimeSeconds, Sensor... parents) {
+    public Sensor sensor(String name, MetricConfig config, long 
inactiveSensorExpirationTimeSeconds, Sensor... parents) {
         return this.sensor(name, config, inactiveSensorExpirationTimeSeconds, 
Sensor.RecordingLevel.INFO, parents);
     }
 
diff --git 
a/server-common/src/main/java/org/apache/kafka/server/util/timer/TimingWheel.java
 
b/server-common/src/main/java/org/apache/kafka/server/util/timer/TimingWheel.java
index f9a2029d09a..db3ac8c129a 100644
--- 
a/server-common/src/main/java/org/apache/kafka/server/util/timer/TimingWheel.java
+++ 
b/server-common/src/main/java/org/apache/kafka/server/util/timer/TimingWheel.java
@@ -128,15 +128,19 @@ public class TimingWheel {
         }
     }
 
-    private synchronized void addOverflowWheel() {
+    private void addOverflowWheel() {
         if (overflowWheel == null) {
-            overflowWheel = new TimingWheel(
-                interval,
-                wheelSize,
-                currentTimeMs,
-                taskCounter,
-                queue
-            );
+            synchronized (this) {
+                if (overflowWheel == null) {
+                    overflowWheel = new TimingWheel(
+                        interval,
+                        wheelSize,
+                        currentTimeMs,
+                        taskCounter,
+                        queue
+                    );
+                }
+            }
         }
     }