--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/ref/NullQueue.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,89 @@
+/*
+ * Copyright 1999 Sun Microsystems, 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.
+ *
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/* @test
+ * @bug 4178693
+ * @summary Ensure that null queue arguments don't crash the Reference handler
+ * @author Mark Reinhold
+ */
+
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+
+
+public class NullQueue {
+
+    private static Reference r = null;
+
+    private static Thread findThread(String name) {
+        /* Find reference-handler thread */
+        ThreadGroup tg = Thread.currentThread().getThreadGroup();
+        for (ThreadGroup tgn = tg;
+             tgn != null;
+             tg = tgn, tgn = tg.getParent());
+        int nt = tg.activeCount();
+        Thread[] ts = new Thread[nt];
+        tg.enumerate(ts);
+        Thread refHandler = null;
+        for (int i = 0; i < ts.length; i++) {
+            if (ts[i].getName().equals(name)) return ts[i];
+        }
+        return null;
+    }
+
+    private static void fork(Runnable proc) throws InterruptedException {
+        Thread t = new Thread(proc);
+        t.start();
+        t.join();
+    }
+
+    public static void main(String[] args) throws Exception {
+
+        Thread refHandler = findThread("Reference Handler");
+        if (refHandler == null)
+            throw new Exception("Couldn't find Reference-handler thread");
+        if (!refHandler.isAlive())
+            throw new Exception("Reference-handler thread is not alive");
+
+        /* Invoke a Reference constructor, passing null for the queue */
+        fork(new Runnable() {
+            public void run() {
+                r = new WeakReference(new Object(), null);
+            }});
+
+        /* Force the reference to be cleared and enqueued by the GC */
+        for (int i = 0;; i++) {
+            Thread.sleep(10);
+            System.gc();
+            if (r.get() == null) break;
+            if (i >= 10)
+                throw new Exception("Couldn't cause weak ref to be cleared");
+        }
+
+        /* Check that the handler is still alive */
+        if (!refHandler.isAlive())
+            throw new Exception("Reference-handler thread died");
+
+    }
+
+}