8273613: JFR: RemoteRecordingStream::start() blocks close()

Reviewed-by: mgronlun

src/jdk.management.jfr/share/classes/jdk/management/jfr/RemoteRecordingStream.java

@@ -520,47 +520,44 @@ public final class RemoteRecordingStream implements EventStream {
 
     @Override
     public void start() {
-        synchronized (lock) { // ensure one starter
-            ensureStartable();
+        ensureStartable();
+        try {
             try {
-                try {
-                    mbean.startRecording(recordingId);
-                } catch (IllegalStateException ise) {
-                    throw ise;
-                }
-                startDownload();
-            } catch (Exception e) {
-                ManagementSupport.logDebug(e.getMessage());
-                close();
-                return;
+                mbean.startRecording(recordingId);
+            } catch (IllegalStateException ise) {
+                throw ise;
             }
-            stream.start();
-            started = true;
+            startDownload();
+        } catch (Exception e) {
+            ManagementSupport.logDebug(e.getMessage());
+            close();
+            return;
         }
+        stream.start();
     }
 
     @Override
     public void startAsync() {
-        synchronized (lock) { // ensure one starter
-            ensureStartable();
-            stream.startAsync();
-            try {
-                mbean.startRecording(recordingId);
-                startDownload();
-            } catch (Exception e) {
-                ManagementSupport.logDebug(e.getMessage());
-                close();
-            }
-            started = true;
+        ensureStartable();
+        stream.startAsync();
+        try {
+            mbean.startRecording(recordingId);
+            startDownload();
+        } catch (Exception e) {
+            ManagementSupport.logDebug(e.getMessage());
+            close();
         }
     }
 
     private void ensureStartable() {
-        if (closed) {
-            throw new IllegalStateException("Event stream is closed");
-        }
-        if (started) {
-            throw new IllegalStateException("Event stream can only be started once");
+        synchronized (lock) {
+            if (closed) {
+                throw new IllegalStateException("Event stream is closed");
+            }
+            if (started) {
+                throw new IllegalStateException("Event stream can only be started once");
+            }
+            started = true;
         }
     }
 

test/jdk/jdk/jfr/jmx/streaming/TestStart.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2021, 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.jmx.streaming;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.util.concurrent.CountDownLatch;
+
+import javax.management.MBeanServerConnection;
+
+import jdk.management.jfr.RemoteRecordingStream;
+
+/**
+ * @test
+ * @key jfr
+ * @summary Sanity tests RemoteRecordingStream::start()
+ * @requires vm.hasJFR
+ * @library /test/lib /test/jdk
+ * @run main/othervm jdk.jfr.jmx.streaming.TestStart
+ */
+public class TestStart {
+
+    private final static MBeanServerConnection CONNECTION = ManagementFactory.getPlatformMBeanServer();
+
+    public static void main(String... args) throws Exception {
+        testStart();
+        testStartTwice();
+        testStartClosed();
+    }
+
+    private static void testStart() throws IOException {
+        try (var r = new RemoteRecordingStream(CONNECTION)) {
+            r.onFlush(() -> {
+                System.out.print("Started.");
+                r.close();
+            });
+            System.out.println("About to start ...");
+            r.start();
+            System.out.println("Finished!");
+        }
+    }
+
+    private static void testStartTwice() throws Exception {
+        var latch = new CountDownLatch(1);
+        try (var r = new RemoteRecordingStream(CONNECTION)) {
+            r.onFlush(() -> latch.countDown());
+            Runnable starter = () -> {
+                r.start();
+            };
+            new Thread(starter).start();
+            latch.await();
+            try {
+                r.start();
+            } catch (IllegalStateException ise) {
+                // OK, as expected
+                return;
+            }
+            throw new Exception("Expected IllegalStateException when starting same stream twice");
+        }
+    }
+
+    private static void testStartClosed() throws Exception {
+        var latch = new CountDownLatch(1);
+        try (var r = new RemoteRecordingStream(CONNECTION)) {
+            r.onFlush(() -> latch.countDown());
+            Runnable starter = () -> {
+                r.start();
+            };
+            new Thread(starter).start();
+            latch.await();
+            r.close();
+            try {
+                r.start();
+            } catch (IllegalStateException ise) {
+                // OK, as expected
+                return;
+            }
+            throw new Exception("Expected IllegalStateException when starting closed stream");
+        }
+    }
+}