Skip emission of internal JFR ThreadPark events

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jfr/events/ThreadParkEvent.java

@@ -1,6 +1,6 @@
 /*
- * Copyright (c) 2022, 2022, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2022, 2022, Red Hat Inc. All rights reserved.
+ * Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2025, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -37,10 +37,21 @@
 import com.oracle.svm.core.jfr.JfrNativeEventWriterDataAccess;
 import com.oracle.svm.core.jfr.JfrTicks;
 import com.oracle.svm.core.jfr.SubstrateJVM;
+import com.oracle.svm.core.monitor.JavaMonitor;
 
 public class ThreadParkEvent {
     public static void emit(long startTicks, Object obj, boolean isAbsolute, long time) {
         if (HasJfrSupport.get()) {
+            /*
+             * Skip emission if corresponding JavaMonitorWait or JavaMonitorEnter events are already
+             * emitted (this is an internal park).
+             */
+            if (obj != null) {
+                Class<?> clazz = obj.getClass();
+                if (clazz.equals(JavaMonitor.class) || (clazz.getEnclosingClass() != null && clazz.getEnclosingClass().isAssignableFrom(JavaMonitor.class))) {
+                    return;
+                }
+            }
             emit0(startTicks, obj, isAbsolute, time);
         }
     }

substratevm/src/com.oracle.svm.test/src/com/oracle/svm/test/jfr/TestOmitInternalParkEvents.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2022, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2025, Red Hat Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.oracle.svm.test.jfr;
+
+import com.oracle.svm.core.jfr.JfrEvent;
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.RecordedClass;
+import jdk.jfr.consumer.RecordedEvent;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.concurrent.locks.LockSupport;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class TestOmitInternalParkEvents extends JfrRecordingTest {
+    private static final int MILLIS = 500;
+    private final Helper helper = new Helper();
+    private Thread firstThread;
+    private Thread secondThread;
+    private volatile boolean passedCheckpoint;
+
+    @Test
+    public void test() throws Throwable {
+        String[] events = new String[]{JfrEvent.JavaMonitorEnter.getName(), JfrEvent.JavaMonitorWait.getName(), JfrEvent.ThreadPark.getName()};
+        Recording recording = startRecording(events);
+
+        // Generate monitor enter events
+        Runnable first = () -> {
+            try {
+                helper.doWork();
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+        };
+
+        Runnable second = () -> {
+            try {
+                passedCheckpoint = true;
+                helper.doWork();
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+        };
+        firstThread = new Thread(first);
+        secondThread = new Thread(second);
+
+        firstThread.start();
+
+        firstThread.join();
+        secondThread.join();
+
+        // Generate monitor wait events
+        try {
+            helper.timeout();
+        } catch (InterruptedException e) {
+            org.junit.Assert.fail(e.getMessage());
+        }
+
+        // Generate thread park events
+        LockSupport.parkNanos(this, MILLIS);
+
+        stopRecording(recording, this::validateEvents);
+    }
+
+    private void validateEvents(List<RecordedEvent> events) {
+        boolean found = false;
+        for (RecordedEvent event : events) {
+            if (event.getEventType().getName().equals(JfrEvent.ThreadPark.getName())) {
+                RecordedClass parkedClass = event.getValue("parkedClass");
+                if (parkedClass != null) {
+                    String parkedClassName = parkedClass.getName();
+                    assertFalse(parkedClassName.contains("com.oracle.svm.core.monitor"));
+                    found = true;
+                }
+            }
+        }
+        assertTrue("Expected jdk.ThreadPark event not found", found);
+    }
+
+    private final class Helper {
+        private synchronized void doWork() throws InterruptedException {
+            if (Thread.currentThread().equals(secondThread)) {
+                return; // second thread doesn't need to do work.
+            }
+            // ensure ordering of critical section entry
+            secondThread.start();
+
+            // spin until second thread blocks
+            while (!secondThread.getState().equals(Thread.State.BLOCKED) || !passedCheckpoint) {
+                Thread.sleep(100);
+            }
+            Thread.sleep(MILLIS);
+        }
+
+        private synchronized void timeout() throws InterruptedException {
+            wait(MILLIS);
+        }
+    }
+}