7042126: (alt-rt) HashMap.clone implementation should be re-examined

Summary: Test case for cr7042126. Issue only found in OracleJDK, but test case is valid for OpenJDK as well
Reviewed-by: mduigou

test/java/util/HashMap/HashMapCloneLeak.java

+/*
+ * Copyright (c) 2013, 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
+ * @bug 7042126
+ * @summary Verify that we do not leak contents when we clone a HashMap
+ * @author david.buck@oracle.com
+ * @run main/othervm HashMapCloneLeak
+ * @run main/othervm -XX:+AggressiveOpts HashMapCloneLeak
+ */
+
+import java.util.HashMap;
+import java.lang.ref.WeakReference;
+
+public class HashMapCloneLeak {
+
+    static WeakReference<Object> wr = null;
+
+    // helper method to keep testObject and map out of main method's scope
+    private static HashMap<Integer, Object> makeMap() {
+        HashMap<Integer, Object> map = new HashMap<Integer, Object>();
+        Object testObject = new Object();
+        wr = new WeakReference<Object>(testObject);
+        map.put(42, testObject);
+        return map;
+    }
+
+    public static void main(String[] args) throws Exception {
+        HashMap<Integer, Object> hm = makeMap();
+        hm = (HashMap<Integer, Object>)hm.clone();
+        hm.clear();
+        // There should no longer be a strong reference to testObject
+        // the WeakReference should be nulled out by GC. If not,
+        // we will hang here until timed out by the test harness.
+        Object[] chain = null;
+        while (wr.get() != null) {
+            try {
+                Object[] allocate = new Object[1000000];
+                allocate[0] = chain;
+                chain = allocate;
+            } catch (OutOfMemoryError oome) {
+                chain = null;
+            }
+            System.gc();
+            Thread.sleep(100);
+        }
+    }
+
+}