--- /dev/null	2020-01-02 04:43:18.583999853 +0000
+++ new/test/jdk/jfr/jvm/TestUnloadEventClassCount.java	2020-01-30 06:37:27.116340867 +0000
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. 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 jdk.jfr.jvm;
+
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+
+import jdk.jfr.Event;
+import jdk.jfr.FlightRecorder;
+import jdk.jfr.internal.JVM;
+
+/**
+ * @test
+ * @key jfr
+ * @summary Unit test for JVM#getUnloadedEventClassCount
+ *
+ *
+ * @library /lib /
+ *
+ *
+ * @run main/othervm -XX:+PrintGCDetails -XX:+PrintGC  -verbose:class -Xmx16m jdk.jfr.jvm.TestUnloadEventClassCount
+ */
+public class TestUnloadEventClassCount {
+
+    private static final String EVENT_NAME = "jdk.jfr.jvm.TestUnloadEventClassCount$ToBeUnloaded";
+
+    public static class ToBeUnloaded extends Event {
+    }
+
+    static public class MyClassLoader extends ClassLoader {
+        public MyClassLoader() {
+            super(null);
+        }
+
+        public final Class<?> defineClass(String name, byte[] b) {
+            return super.defineClass(name, b, 0, b.length);
+        }
+    }
+
+    public static MyClassLoader myClassLoader;
+
+    public static void main(String[] args) throws Throwable {
+        FlightRecorder.getFlightRecorder();
+        myClassLoader = createClassLoaderWithEventClass();
+        System.out.println("MyClassLoader instance created");
+        long initialCount = JVM.getJVM().getUnloadedEventClassCount();
+        System.out.println("Initiali unloaded count is " + initialCount);
+        myClassLoader = null;
+        System.out.println("Reference to class loader cleared");
+        long count = 0;
+        do {
+            System.gc();
+            System.out.println("GC triggered");
+            count = JVM.getJVM().getUnloadedEventClassCount();
+            System.out.println("Unloaded count was " + count);
+            Thread.sleep(1000); // sleep to reduce log
+        } while (count != initialCount + 1);
+    }
+
+    private static MyClassLoader createClassLoaderWithEventClass() throws Exception {
+        String resourceName = EVENT_NAME.replace('.', '/') + ".class";
+        try (InputStream is = TestUnloadEventClassCount.class.getClassLoader().getResourceAsStream(resourceName)) {
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            byte[] buffer = new byte[4096];
+            int byteValue = 0;
+            while ((byteValue = is.read(buffer, 0, buffer.length)) != -1) {
+                baos.write(buffer, 0, byteValue);
+            }
+            baos.flush();
+            MyClassLoader myClassLoader = new MyClassLoader();
+            Class<?> eventClass = myClassLoader.defineClass(EVENT_NAME, baos.toByteArray());
+            if (eventClass == null) {
+                throw new Exception("Could not define test class");
+            }
+            if (eventClass.getSuperclass() != Event.class) {
+                throw new Exception("Superclass should be jdk.jfr.Event");
+            }
+            if (eventClass.getSuperclass().getClassLoader() != null) {
+                throw new Exception("Class loader of jdk.jfr.Event should be null");
+            }
+            if (eventClass.getClassLoader() != myClassLoader) {
+                throw new Exception("Incorrect class loader for event class");
+            }
+            eventClass.newInstance(); // force <clinit>
+            return myClassLoader;
+        }
+    }
+}