--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/nio/channels/Selector/SelectorUtils.java	Fri Aug 31 10:00:22 2018 +0800
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2018, 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.
+ */
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.MonitorInfo;
+import java.lang.management.ThreadInfo;
+import java.nio.channels.Selector;
+
+public class SelectorUtils {
+
+    /**
+     * tell if the monitor of an Object is held by a Thread.
+     * @param t    the Thread to hold the monitor of the selected-key set
+     * @param lock the Object
+     * @return
+     */
+    public static boolean mightHoldLock(Thread t, Object lock) {
+        long tid = t.getId();
+        int hash = System.identityHashCode(lock);
+        ThreadInfo ti = ManagementFactory.getThreadMXBean().
+                getThreadInfo(new long[]{ tid} , true, false, 100)[0];
+        if (ti != null) {
+            for (MonitorInfo mi : ti.getLockedMonitors()) {
+                if (mi.getIdentityHashCode() == hash)
+                    return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Spin until the monitor of the selected-key set is likely held
+     * as selected operations are specified to synchronize on the
+     * selected-key set.
+     * @param t   the Thread to hold the monitor of the selected-key set
+     * @param sel the Selector
+     * @throws Exception
+     */
+    public static void spinUntilLocked(Thread t, Selector sel) throws Exception {
+        while (!mightHoldLock(t, sel.selectedKeys())) {
+            Thread.sleep(50);
+        }
+    }
+}