Support jdk.CPUTimeSample event in ProfileResults for Java 25+ (JEP 509)

build-tools/build-infra/src/main/java/org/apache/lucene/gradle/plugins/java/CodeProfilingPlugin.java

@@ -20,6 +20,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.List;
+import java.util.Locale;
 import org.apache.lucene.gradle.plugins.LuceneGradlePlugin;
 import org.gradle.api.DefaultTask;
 import org.gradle.api.GradleException;
@@ -189,7 +190,7 @@ public void apply(Project project) {
             task.jvmArgs(
                 List.of(
                     "-XX:StartFlightRecording=dumponexit=true,maxsize=250M,settings="
-                        + gradlePluginResource(project, "testing/profiling.jfc"),
+                        + gradlePluginResource(project, profilingSettingsPath()),
                     "-XX:+UnlockDiagnosticVMOptions",
                     "-XX:+DebugNonSafepoints"));
             task.dependsOn(cleanPreviousProfiles);
@@ -254,4 +255,15 @@ private record ProfilingOptions(
       Provider<Integer> countOption,
       Provider<Boolean> lineNumbersOption,
       Provider<Boolean> frametypesOption) {}
+
+  /**
+   * Java 25+ JEP 509 ({@code jdk.CPUTimeSample}) is currently implemented only on Linux in the JDK.
+   * When the Gradle host is Linux, use {@code testing/profiling.cputime.jfc} (CPU-time sampling
+   * only). Otherwise use {@code testing/profiling.jfc} (legacy wall-clock execution sampling). Host
+   * selection may broaden if CPU-time sampling is supported on other OS releases later.
+   */
+  private static String profilingSettingsPath() {
+    String os = System.getProperty("os.name", "").toLowerCase(Locale.ROOT);
+    return os.contains("linux") ? "testing/profiling.cputime.jfc" : "testing/profiling.jfc";
+  }
 }

build-tools/build-infra/src/main/java/org/apache/lucene/gradle/plugins/java/ProfileResults.java

@@ -105,8 +105,16 @@ static boolean isInteresting(String mode, RecordedEvent event) {
     String name = event.getEventType().getName();
     switch (mode) {
       case "cpu":
-        return (name.equals("jdk.ExecutionSample") || name.equals("jdk.NativeMethodSample"))
-            && !isGradlePollThread(event.getThread("sampledThread"));
+        // jdk.CPUTimeSample: JEP 509 (e.g. gradle/testing/profiling.cputime.jfc). Legacy samples:
+        // jdk.ExecutionSample / jdk.NativeMethodSample (e.g. profiling.jfc). Stock Lucene configs
+        // enable one family; filter gradle poll thread for legacy samples only.
+        if (name.equals("jdk.CPUTimeSample")) {
+          return true;
+        }
+        if (name.equals("jdk.ExecutionSample") || name.equals("jdk.NativeMethodSample")) {
+          return !isGradlePollThread(event.getThread("sampledThread"));
+        }
+        return false;
       case "heap":
         return (name.equals("jdk.ObjectAllocationInNewTLAB")
                 || name.equals("jdk.ObjectAllocationOutsideTLAB"))
@@ -132,6 +140,8 @@ static long getValue(RecordedEvent event) {
         return 1L;
       case "jdk.NativeMethodSample":
         return 1L;
+      case "jdk.CPUTimeSample":
+        return 1L;
       default:
         throw new UnsupportedOperationException(event.toString());
     }
@@ -173,6 +183,7 @@ public static void printReport(
     if (count < 1) {
       throw new IllegalArgumentException("tests.profile.count must be positive");
     }
+
     Map<String, SimpleEntry<String, Long>> histogram = new HashMap<>();
     int totalEvents = 0;
     long sumValues = 0;

gradle/testing/profiling.cputime.jfc

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one or more
+    contributor license agreements.  See the NOTICE file distributed with
+    this work for additional information regarding copyright ownership.
+    The ASF licenses this file to You 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.
+-->
+<!--
+  CPU-time method sampling (Java 25+, JEP 509, jdk.CPUTimeSample). Used when CPU-time profiling
+  is available for the test JVM (currently only on Linux for this JDK).
+
+  Object allocation events match profiling.jfc for heap profiling mode.
+-->
+<configuration version="2.0" label="TestProfilingCpuTime" description="CPU-time sampling for tests (JEP 509)" provider="Apache">
+  <event name="jdk.CPUTimeSample">
+    <setting name="enabled">true</setting>
+    <setting name="throttle">1 ms</setting>
+  </event>
+
+  <event name="jdk.ObjectAllocationInNewTLAB">
+    <setting name="enabled">true</setting>
+    <setting name="stackTrace">true</setting>
+  </event>
+
+  <event name="jdk.ObjectAllocationOutsideTLAB">
+    <setting name="enabled">true</setting>
+    <setting name="stackTrace">true</setting>
+  </event>
+</configuration>

gradle/testing/profiling.jfc

@@ -16,7 +16,9 @@
     limitations under the License.
 -->
 <!--
-Collects only execution and method samples at a low interval
+  Wall-clock execution samples for CPU profiling when JEP 509 CPU-time sampling is not used for
+  tests (see profiling.cputime.jfc on hosts where CodeProfilingPlugin selects it).
+  Heap allocation events are enabled on all platforms.
 -->
 <configuration version="2.0" label="TestProfiling" description="Sampling for unit tests" provider="Apache">
   <event name="jdk.ExecutionSample">

lucene/CHANGES.txt

@@ -185,6 +185,11 @@ Changes in Runtime Behavior
 
 Build
 ---------------------
+* GITHUB#15926: Use the Java 25+ (JEP 509) CPU-time sampling profiler when available (currently
+  only on Linux), and fall back to legacy wall-clock execution sampling elsewhere. ProfileResults
+  recognizes jdk.CPUTimeSample; CodeProfilingPlugin picks gradle/testing/profiling.cputime.jfc or
+  profiling.jfc by host OS. (Prithvi S)
+
 * GITHUB#15327: New low-level build options to detect abuse of LuceneTestCase.random():
   tests.random.maxacquires and tests.random.maxcalls (Robert Muir, Dawid Weiss)