diff --git a/jdk/test/java/nio/channels/AsynchronousChannelGroup/AsExecutor.java b/jdk/test/java/nio/channels/AsynchronousChannelGroup/AsExecutor.java
index f5c10e4cf73..db720d8bc26 100644
--- a/jdk/test/java/nio/channels/AsynchronousChannelGroup/AsExecutor.java
+++ b/jdk/test/java/nio/channels/AsynchronousChannelGroup/AsExecutor.java
@@ -37,24 +37,30 @@ public class AsExecutor {
             .withFixedThreadPool(5, factory);
         AsynchronousChannelGroup group2 = AsynchronousChannelGroup
             .withCachedThreadPool(Executors.newCachedThreadPool(factory), 0);
+        AsynchronousChannelGroup group3 = AsynchronousChannelGroup
+            .withThreadPool(Executors.newFixedThreadPool(10, factory));
 
         try {
             // execute simple tasks
             testSimpleTask(group1);
             testSimpleTask(group2);
+            testSimpleTask(group3);
 
             // install security manager and test again
             System.setSecurityManager( new SecurityManager() );
             testSimpleTask(group1);
             testSimpleTask(group2);
+            testSimpleTask(group3);
 
             // attempt to execute tasks that run with only frames from boot
             // class loader on the stack.
             testAttackingTask(group1);
             testAttackingTask(group2);
+            testAttackingTask(group3);
         } finally {
             group1.shutdown();
             group2.shutdown();
+            group3.shutdown();
         }
     }
 
diff --git a/jdk/test/java/nio/channels/AsynchronousChannelGroup/Basic.java b/jdk/test/java/nio/channels/AsynchronousChannelGroup/Basic.java
index 02a9f73ced5..8f5fc96c5c8 100644
--- a/jdk/test/java/nio/channels/AsynchronousChannelGroup/Basic.java
+++ b/jdk/test/java/nio/channels/AsynchronousChannelGroup/Basic.java
@@ -51,98 +51,135 @@ public class Basic {
         miscTests();
     }
 
+    static void testShutdownWithNoChannels(ExecutorService pool,
+                                           AsynchronousChannelGroup group)
+        throws Exception
+    {
+        group.shutdown();
+        if (!group.isShutdown())
+            throw new RuntimeException("Group should be shutdown");
+        // group should terminate quickly
+        boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
+        if (!terminated)
+            throw new RuntimeException("Group should have terminated");
+        if (pool != null && !pool.isTerminated())
+            throw new RuntimeException("Executor should have terminated");
+    }
+
+    static void testShutdownWithChannels(ExecutorService pool,
+                                         AsynchronousChannelGroup group)
+        throws Exception
+    {
+
+        // create channel that is bound to group
+        AsynchronousChannel ch;
+        switch (rand.nextInt(2)) {
+            case 0 : ch = AsynchronousSocketChannel.open(group); break;
+            case 1 : ch = AsynchronousServerSocketChannel.open(group); break;
+            default : throw new AssertionError();
+        }
+        group.shutdown();
+        if (!group.isShutdown())
+            throw new RuntimeException("Group should be shutdown");
+
+        // last channel so should terminate after this channel is closed
+        ch.close();
+
+        // group should terminate quickly
+        boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
+        if (!terminated)
+            throw new RuntimeException("Group should have terminated");
+        if (pool != null && !pool.isTerminated())
+            throw new RuntimeException("Executor should have terminated");
+    }
+
     static void shutdownTests() throws Exception {
         System.out.println("-- test shutdown --");
 
         // test shutdown with no channels in groups
-        for (int i=0; i<500; i++) {
-            ExecutorService pool = null;
-            AsynchronousChannelGroup group;
-            if (rand.nextBoolean()) {
-                pool = Executors.newCachedThreadPool();
-                group = AsynchronousChannelGroup.withCachedThreadPool(pool, rand.nextInt(5));
-            } else {
-                int nThreads = 1 + rand.nextInt(8);
-                group = AsynchronousChannelGroup.withFixedThreadPool(nThreads, threadFactory);
-            }
-            group.shutdown();
-            if (!group.isShutdown())
-                throw new RuntimeException("Group should be shutdown");
-            // group should terminate quickly
-            boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
-            if (!terminated)
-                throw new RuntimeException("Group should have terminated");
-            if (pool != null && !pool.isTerminated())
-                throw new RuntimeException("Executor should have terminated");
+        for (int i = 0; i < 100; i++) {
+            ExecutorService pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withCachedThreadPool(pool, rand.nextInt(5));
+            testShutdownWithNoChannels(pool, group);
+        }
+        for (int i = 0; i < 100; i++) {
+            int nThreads = 1 + rand.nextInt(8);
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withFixedThreadPool(nThreads, threadFactory);
+            testShutdownWithNoChannels(null, group);
+        }
+        for (int i = 0; i < 100; i++) {
+            ExecutorService pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withThreadPool(pool);
+            testShutdownWithNoChannels(pool, group);
         }
 
-        // shutdown with channel in group
-        for (int i=0; i<500; i++) {
-            ExecutorService pool = null;
-            AsynchronousChannelGroup group;
-            if (rand.nextBoolean()) {
-                pool = Executors.newCachedThreadPool();
-                group = AsynchronousChannelGroup.withCachedThreadPool(pool, rand.nextInt(10));
-            } else {
-                int nThreads = 1 + rand.nextInt(8);
-                group = AsynchronousChannelGroup.withFixedThreadPool(nThreads, threadFactory);
-            }
-            // create channel that is bound to group
-            AsynchronousChannel ch;
-            switch (rand.nextInt(2)) {
-                case 0 : ch = AsynchronousSocketChannel.open(group); break;
-                case 1 : ch = AsynchronousServerSocketChannel.open(group); break;
-                default : throw new AssertionError();
-            }
-            group.shutdown();
-            if (!group.isShutdown())
-                throw new RuntimeException("Group should be shutdown");
-
-            // last channel so should terminate after this channel is closed
-            ch.close();
-
-            // group should terminate quickly
-            boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
-            if (!terminated)
-                throw new RuntimeException("Group should have terminated");
-            if (pool != null && !pool.isTerminated())
-                throw new RuntimeException("Executor should have terminated");
+        // test shutdown with channel in group
+        for (int i = 0; i < 100; i++) {
+            ExecutorService pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withCachedThreadPool(pool, rand.nextInt(10));
+            testShutdownWithChannels(pool, group);
         }
+        for (int i = 0; i < 100; i++) {
+            int nThreads = 1 + rand.nextInt(8);
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withFixedThreadPool(nThreads, threadFactory);
+            testShutdownWithChannels(null, group);
+        }
+        for (int i = 0; i < 100; i++) {
+            ExecutorService pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withThreadPool(pool);
+            testShutdownWithChannels(pool, group);
+        }
+    }
+
+    static void testShutdownNow(ExecutorService pool,
+                                AsynchronousChannelGroup group)
+        throws Exception
+    {
+        // I/O in progress
+        AsynchronousServerSocketChannel ch = AsynchronousServerSocketChannel
+                .open(group).bind(new InetSocketAddress(0));
+        ch.accept();
+
+        // forceful shutdown
+        group.shutdownNow();
+
+        // shutdownNow is required to close all channels
+        if (ch.isOpen())
+            throw new RuntimeException("Channel should be closed");
+
+        boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
+        if (!terminated)
+            throw new RuntimeException("Group should have terminated");
+        if (pool != null && !pool.isTerminated())
+            throw new RuntimeException("Executor should have terminated");
     }
 
     static void shutdownNowTests() throws Exception {
         System.out.println("-- test shutdownNow --");
 
-        for (int i=0; i< 10; i++) {
-            ExecutorService pool = null;
-            AsynchronousChannelGroup group;
-            if (rand.nextBoolean()) {
-                pool = Executors.newCachedThreadPool();
-                group = AsynchronousChannelGroup
+        for (int i = 0; i < 10; i++) {
+            ExecutorService pool = pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
                     .withCachedThreadPool(pool, rand.nextInt(5));
-            } else {
-                int nThreads = 1 + rand.nextInt(8);
-                group = AsynchronousChannelGroup
+            testShutdownNow(pool, group);
+        }
+        for (int i = 0; i < 10; i++) {
+            int nThreads = 1 + rand.nextInt(8);
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
                     .withFixedThreadPool(nThreads, threadFactory);
-            }
-
-            // I/O in progress
-            AsynchronousServerSocketChannel ch = AsynchronousServerSocketChannel
-                .open(group).bind(new InetSocketAddress(0));
-            ch.accept();
-
-            // forceful shutdown
-            group.shutdownNow();
-
-            // shutdownNow is required to close all channels
-            if (ch.isOpen())
-                throw new RuntimeException("Channel should be closed");
-
-            boolean terminated = group.awaitTermination(3, TimeUnit.SECONDS);
-            if (!terminated)
-                throw new RuntimeException("Group should have terminated");
-            if (pool != null && !pool.isTerminated())
-                throw new RuntimeException("Executor should have terminated");
+            testShutdownNow(null, group);
+        }
+        for (int i = 0; i < 10; i++) {
+            ExecutorService pool = Executors.newCachedThreadPool();
+            AsynchronousChannelGroup group = AsynchronousChannelGroup
+                    .withThreadPool(pool);
+            testShutdownNow(pool, group);
         }
     }
 
@@ -245,5 +282,10 @@ public class Basic {
             throw new RuntimeException("NPE expected");
         } catch (NullPointerException x) {
         }
+        try {
+            AsynchronousChannelGroup.withThreadPool(null);
+            throw new RuntimeException("NPE expected");
+        } catch (NullPointerException e) {
+        }
     }
 }
diff --git a/jdk/test/java/nio/channels/AsynchronousChannelGroup/Restart.java b/jdk/test/java/nio/channels/AsynchronousChannelGroup/Restart.java
index 1beb2243085..351770f3e77 100644
--- a/jdk/test/java/nio/channels/AsynchronousChannelGroup/Restart.java
+++ b/jdk/test/java/nio/channels/AsynchronousChannelGroup/Restart.java
@@ -71,17 +71,23 @@ public class Restart {
         testRestart(group, 100);
         group.shutdown();
 
-        // group with custom thread pool
+        // group with cached thread pool
         ExecutorService pool = Executors.newCachedThreadPool(factory);
         group = AsynchronousChannelGroup.withCachedThreadPool(pool, rand.nextInt(5));
         testRestart(group, 100);
         group.shutdown();
 
+        // group with custom thread pool
+        group = AsynchronousChannelGroup
+                .withThreadPool(Executors.newFixedThreadPool(1+rand.nextInt(5), factory));
+        testRestart(group, 100);
+        group.shutdown();
+
         // give time for threads to terminate
         Thread.sleep(3000);
         int actual = exceptionCount.get();
-        if (actual != 200)
-            throw new RuntimeException(actual + " exceptions, expected: " + 200);
+        if (actual != 300)
+            throw new RuntimeException(actual + " exceptions, expected: " + 300);
     }
 
     static void testRestart(AsynchronousChannelGroup group, int count)