--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/EventEmitterAgent.java	Thu Aug 22 10:35:31 2019 -0700
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2019, 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.
+ *
+ * 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.javaagent;
+
+import java.lang.instrument.Instrumentation;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import jdk.jfr.Configuration;
+import jdk.jfr.Event;
+import jdk.jfr.Name;
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.RecordingFile;
+import jdk.test.lib.Asserts;
+import jdk.test.lib.jfr.EventNames;
+
+// Java agent that emits in multiple threads
+public class EventEmitterAgent {
+
+    private static final int THREADS = 5;
+    private static final int EVENTS_PER_THREAD = 150_000;
+    private static final int EXPECTED_COUNT = THREADS * EVENTS_PER_THREAD;
+    private static final Path DUMP_PATH = Paths.get("dump.jfr").toAbsolutePath();
+
+    // Called when agent is loaded from command line
+    public static void agentmain(String agentArgs, Instrumentation inst) throws Exception {
+        agentWork();
+    }
+
+    // Called when agent is dynamically loaded
+    public static void premain(String agentArgs, Instrumentation inst) throws Exception {
+        agentWork();
+    }
+
+    private static void agentWork() throws Exception {
+        try (Recording r = new Recording(Configuration.getConfiguration("default"))) {
+            r.enable(EventNames.JavaExceptionThrow);
+            r.setDestination(DUMP_PATH);
+            r.start();
+            Thread[] threads = new Thread[THREADS];
+            for (int i = 0; i < THREADS; i++) {
+                threads[i] = new Thread(EventEmitterAgent::emitEvents);
+                threads[i].start();
+            }
+            for (int i = 0; i < THREADS; i++) {
+                threads[i].join();
+            }
+            r.stop();
+        }
+    }
+
+    public static void emitEvents() {
+        for (int i = 0; i < EVENTS_PER_THREAD; i++) {
+            TestEvent e = new TestEvent();
+            e.msg = "Long message that puts pressure on the string pool " + i % 100;
+            e.count = i;
+            e.thread = Thread.currentThread();
+            e.clazz = String.class;
+            e.commit();
+            if (i % 10000 == 0) {
+                try {
+                    Thread.sleep(1);
+                } catch (InterruptedException ie) {
+                    // ignore
+                }
+            }
+        }
+    }
+
+    @Name("Test")
+    static class TestEvent extends Event {
+        String msg;
+        int count;
+        Thread thread;
+        Class<?> clazz;
+    }
+
+    public static void validateRecording() throws Exception {
+        long testEventCount = RecordingFile.readAllEvents(DUMP_PATH)
+                .stream()
+                .filter(e -> e.getEventType().getName().equals("Test"))
+                .count();
+        Asserts.assertTrue(testEventCount == EXPECTED_COUNT, "Mismatch in TestEvent count");
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/JavaAgentBuilder.java	Thu Aug 22 10:35:31 2019 -0700
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2019, 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.
+ *
+ * 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.test.lib.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.jar.Attributes;
+import java.util.jar.Manifest;
+
+import jdk.test.lib.Utils;
+import jdk.test.lib.util.JarUtils;
+
+/**
+ * A builder for a common Java agent.
+ * Can be used directly from the jtreg test header to
+ * build a java agent before the test is executed.
+ *
+ * E.g.:
+ * @run driver jdk.test.lib.util.JavaAgentBuilder
+ *             jdk.jfr.javaagent.EventEmitterAgent EventEmitterAgent.jar
+ *
+ */
+public class JavaAgentBuilder {
+
+    /**
+     * Build a java agent jar file with a given agent class.
+     *
+     * @param args[0]    fully qualified name of an agent class
+     * @param args[1]    file name of the agent jar to be created
+     * @throws IOException
+     */
+    public static void main(String... args) throws IOException {
+        String agentClass = args[0];
+        String agentJar = args[1];
+        System.out.println("Building " + agentJar + " with agent class " + agentClass);
+        build(agentClass, agentJar);
+    }
+
+    /**
+     * Build a java agent jar file with a given agent class.
+     * The agent class will be added as both premain class and agent class.
+     *
+     * @param agentClass fully qualified name of an agent class
+     * @param agentJar   file name of the agent jar to be created
+     *                   the file will be placed in a current work directory
+     * @throws IOException
+     */
+    public static void build(String agentClass, String agentJar) throws IOException {
+        Manifest mf = new Manifest();
+        Attributes attrs = mf.getMainAttributes();
+        attrs.put(Attributes.Name.MANIFEST_VERSION, "1.0");
+        attrs.putValue("Premain-Class", agentClass);
+        attrs.putValue("Agent-Class", agentClass);
+
+        Path jarFile = Paths.get(".", agentJar);
+        String testClasses = Utils.TEST_CLASSES;
+        String agentPath = agentClass.replace(".", File.separator) + ".class";
+        Path agentFile = Paths.get(testClasses, agentPath);
+        Path dir = Paths.get(testClasses);
+        JarUtils.createJarFile(jarFile, mf, dir, agentFile);
+        System.out.println("Agent built:" + jarFile.toAbsolutePath());
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/TestLoadedAgent.java	Thu Aug 22 10:35:31 2019 -0700
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2019, 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.
+ *
+ * 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.
+ */
+
+/**
+ * @test
+ * @key jfr
+ * @summary Tests emitting events in a dynamically loaded Java agent
+ * @requires vm.hasJFR
+ *
+ * @library /test/lib /test/jdk
+ * @modules java.instrument
+ *
+ * @build jdk.jfr.javaagent.EventEmitterAgent
+ *
+ * @run driver jdk.test.lib.util.JavaAgentBuilder
+ *             jdk.jfr.javaagent.EventEmitterAgent EventEmitterAgent.jar
+ *
+ * @run main/othervm -Djdk.attach.allowAttachSelf=true jdk.jfr.javaagent.TestLoadedAgent
+ */
+
+package jdk.jfr.javaagent;
+
+import com.sun.tools.attach.VirtualMachine;
+import jdk.jfr.FlightRecorder;
+import jdk.jfr.FlightRecorderListener;
+import jdk.jfr.Recording;
+import jdk.jfr.RecordingState;
+
+
+public class TestLoadedAgent {
+    public static void main(String... arg) throws Exception {
+        long pid = ProcessHandle.current().pid();
+        VirtualMachine vm = VirtualMachine.attach(Long.toString(pid));
+        vm.loadAgent("EventEmitterAgent.jar");
+        vm.detach();
+        EventEmitterAgent.validateRecording();
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/TestPremainAgent.java	Thu Aug 22 10:35:31 2019 -0700
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2019, 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.
+ *
+ * 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.
+ */
+
+/**
+ * @test
+ * @key jfr
+ * @summary Tests emitting event before main using a Java agent
+ * @requires vm.hasJFR
+ *
+ * @library /test/lib
+ * @modules java.instrument
+ *
+ * @build jdk.jfr.javaagent.EventEmitterAgent
+ *
+ * @run driver jdk.test.lib.util.JavaAgentBuilder
+ *             jdk.jfr.javaagent.EventEmitterAgent EventEmitterAgent.jar
+ *
+ * @run main/othervm -javaagent:EventEmitterAgent.jar jdk.jfr.javaagent.TestPremainAgent
+ */
+
+package jdk.jfr.javaagent;
+
+
+public class TestPremainAgent {
+    public static void main(String... arg) throws Exception {
+        EventEmitterAgent.validateRecording();
+    }
+}