diff -r 2c3cc4b01880 -r c16ac7a2eba4 test/jdk/jdk/jfr/api/consumer/filestream/TestReuse.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/api/consumer/filestream/TestReuse.java	Wed Oct 30 19:43:52 2019 +0100
@@ -0,0 +1,128 @@
+/*
+ * 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.  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.api.consumer.filestream;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import jdk.jfr.Event;
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.EventStream;
+import jdk.jfr.consumer.RecordedEvent;
+
+/**
+ * @test
+ * @summary Test EventStream::setReuse(...)
+ * @key jfr
+ * @requires vm.hasJFR
+ * @library /test/lib
+ * @run main/othervm jdk.jfr.api.consumer.filestream.TestReuse
+ */
+public class TestReuse {
+
+    static class ReuseEvent extends Event {
+    }
+
+    private static final boolean[] BOOLEAN_STATES = { false, true };
+
+    public static void main(String... args) throws Exception {
+        Path p = makeRecording();
+
+        testSetReuseTrue(p);
+        testSetReuseFalse(p);
+    }
+
+    private static void testSetReuseFalse(Path p) throws Exception {
+        for (boolean ordered : BOOLEAN_STATES) {
+            AtomicBoolean fail = new AtomicBoolean(false);
+            Map<RecordedEvent, RecordedEvent> identity = new IdentityHashMap<>();
+            try (EventStream es = EventStream.openFile(p)) {
+                es.setOrdered(ordered);
+                es.setReuse(false);
+                es.onEvent(e -> {
+                    if (identity.containsKey(e)) {
+                        fail.set(true);
+                        es.close();
+                    }
+                    identity.put(e, e);
+                });
+                es.start();
+            }
+            if (fail.get()) {
+                throw new Exception("Unexpected reuse! Ordered = " + ordered);
+            }
+
+        }
+    }
+
+    private static void testSetReuseTrue(Path p) throws Exception {
+        for (boolean ordered : BOOLEAN_STATES) {
+            AtomicBoolean success = new AtomicBoolean(false);
+            Map<RecordedEvent, RecordedEvent> events = new IdentityHashMap<>();
+            try (EventStream es = EventStream.openFile(p)) {
+                es.setOrdered(ordered);
+                es.setReuse(true);
+                es.onEvent(e -> {
+                    if(events.containsKey(e)) {
+                        success.set(true);;
+                        es.close();
+                    }
+                    events.put(e,e);
+                });
+                es.start();
+            }
+            if (!success.get()) {
+                throw new Exception("No reuse! Ordered = " + ordered);
+            }
+        }
+
+    }
+
+    private static Path makeRecording() throws IOException {
+        try (Recording r = new Recording()) {
+            r.start();
+            for (int i = 0; i < 5; i++) {
+                ReuseEvent e = new ReuseEvent();
+                e.commit();
+            }
+            Recording rotation = new Recording();
+            rotation.start();
+            for (int i = 0; i < 5; i++) {
+                ReuseEvent e = new ReuseEvent();
+                e.commit();
+            }
+            r.stop();
+            rotation.close();
+            Path p = Files.createTempFile("recording", ".jfr");
+            r.dump(p);
+            return p;
+        }
+    }
+}