* Improved the throughput of the server-side accept operation

* Added FastQueue.isEmpty()

src/main/java/org/jboss/netty/channel/socket/nio/NioServerSocketPipelineSink.java

@@ -202,10 +202,6 @@ class NioServerSocketPipelineSink extends AbstractChannelSink {
             for (;;) {
                 try {
                     SocketChannel acceptedSocket = channel.socket.accept();
-                    if (acceptedSocket == null) {
-                        continue;
-                    }
-
                     try {
                         ChannelPipeline pipeline =
                             channel.getConfig().getPipelineFactory().getPipeline();

src/main/java/org/jboss/netty/channel/socket/nio/NioWorker.java

@@ -32,7 +32,6 @@ import java.nio.channels.ScatteringByteChannel;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.Selector;
 import java.util.Iterator;
-import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.Executor;
@@ -72,11 +71,15 @@ class NioWorker implements Runnable {
     private final int id;
     private final Executor executor;
     private final AtomicBoolean started = new AtomicBoolean();
-    volatile Thread thread;
+    private volatile Thread thread;
-    volatile Selector selector;
+    private volatile Selector selector;
-    final AtomicBoolean wakenUp = new AtomicBoolean();
+    private final AtomicBoolean wakenUp = new AtomicBoolean();
-    final ReadWriteLock selectorGuard = new ReentrantReadWriteLock();
+    private final ReadWriteLock selectorGuard = new ReentrantReadWriteLock();
-    final Queue<Runnable> taskQueue = new ConcurrentLinkedQueue<Runnable>();
+    private final ReadWriteLock shutdownLock = new ReentrantReadWriteLock();
+    //private final FastQueue<Runnable> taskQueue = new FastQueue<Runnable>();
+    //private final ConcurrentFastQueue<Runnable> taskQueue = new ConcurrentFastQueue<Runnable>();
+    private final FastQueue<Runnable> registerTaskQueue = new FastQueue<Runnable>();
+    private final ConcurrentLinkedQueue<Runnable> writeTaskQueue = new ConcurrentLinkedQueue<Runnable>();
 
     NioWorker(int bossId, int id, Executor executor) {
         this.bossId = bossId;
@@ -104,60 +107,24 @@ class NioWorker implements Runnable {
             }
         }
 
+        boolean server = !(channel instanceof NioClientSocketChannel);
+        Runnable registerTask = new RegisterTask(selector, channel, future, server);
         if (firstChannel) {
-            try {
+            registerTask.run();
-                channel.socket.register(selector, SelectionKey.OP_READ, channel);
-                if (future != null) {
-                    future.setSuccess();
-                }
-            } catch (ClosedChannelException e) {
-                future.setFailure(e);
-                throw new ChannelException(
-                        "Failed to register a socket to the selector.", e);
-            }
-
-            boolean server = !(channel instanceof NioClientSocketChannel);
-            if (server) {
-                fireChannelOpen(channel);
-                fireChannelBound(channel, channel.getLocalAddress());
-            } else if (!((NioClientSocketChannel) channel).boundManually) {
-                fireChannelBound(channel, channel.getLocalAddress());
-            }
-            fireChannelConnected(channel, channel.getRemoteAddress());
-
             String threadName =
                 (server ? "New I/O server worker #"
                         : "New I/O client worker #") + bossId + '-' + id;
 
             executor.execute(new ThreadRenamingRunnable(this, threadName));
         } else {
-            selectorGuard.readLock().lock();
+            shutdownLock.readLock().lock();
             try {
-                if (wakenUp.compareAndSet(false, true)) {
+                registerTaskQueue.offer(registerTask);
-                    selector.wakeup();
-                }
-
-                try {
-                    channel.socket.register(selector, SelectionKey.OP_READ, channel);
-                    if (future != null) {
-                        future.setSuccess();
-                    }
-                } catch (ClosedChannelException e) {
-                    future.setFailure(e);
-                    throw new ChannelException(
-                            "Failed to register a socket to the selector.", e);
-                }
-
-                boolean server = !(channel instanceof NioClientSocketChannel);
-                if (server) {
-                    fireChannelOpen(channel);
-                    fireChannelBound(channel, channel.getLocalAddress());
-                } else if (!((NioClientSocketChannel) channel).boundManually) {
-                    fireChannelBound(channel, channel.getLocalAddress());
-                }
-                fireChannelConnected(channel, channel.getRemoteAddress());
             } finally {
-                selectorGuard.readLock().unlock();
+                shutdownLock.readLock().unlock();
+            }
+            if (wakenUp.compareAndSet(false, true)) {
+                selector.wakeup();
             }
         }
     }
@@ -170,15 +137,18 @@ class NioWorker implements Runnable {
         for (;;) {
             wakenUp.set(false);
 
-            selectorGuard.writeLock().lock();
+            if (CONSTRAINT_LEVEL != 0) {
-                // This empty synchronization block prevents the selector
+                selectorGuard.writeLock().lock();
-                // from acquiring its lock.
+                    // This empty synchronization block prevents the selector
-            selectorGuard.writeLock().unlock();
+                    // from acquiring its lock.
+                selectorGuard.writeLock().unlock();
+            }
 
             try {
                 int selectedKeyCount = selector.select(500);
 
-                processTaskQueue();
+                processRegisterTaskQueue();
+                processWriteTaskQueue();
 
                 if (selectedKeyCount > 0) {
                     processSelectedKeys(selector.selectedKeys());
@@ -193,9 +163,9 @@ class NioWorker implements Runnable {
                     if (shutdown ||
                         executor instanceof ExecutorService && ((ExecutorService) executor).isShutdown()) {
 
-                        selectorGuard.writeLock().lock();
+                        shutdownLock.writeLock().lock();
                         try {
-                            if (selector.keys().isEmpty()) {
+                            if (registerTaskQueue.isEmpty() && selector.keys().isEmpty()) {
                                 try {
                                     selector.close();
                                 } catch (IOException e) {
@@ -210,7 +180,7 @@ class NioWorker implements Runnable {
                                 shutdown = false;
                             }
                         } finally {
-                            selectorGuard.writeLock().unlock();
+                            shutdownLock.writeLock().unlock();
                         }
                     } else {
                         // Give one more second.
@@ -233,9 +203,20 @@ class NioWorker implements Runnable {
         }
     }
 
-    private void processTaskQueue() {
+    private void processRegisterTaskQueue() {
         for (;;) {
-            final Runnable task = taskQueue.poll();
+            final Runnable task = registerTaskQueue.poll();
+            if (task == null) {
+                break;
+            }
+
+            task.run();
+        }
+    }
+
+    private void processWriteTaskQueue() {
+        for (;;) {
+            final Runnable task = writeTaskQueue.poll();
             if (task == null) {
                 break;
             }
@@ -390,7 +371,7 @@ class NioWorker implements Runnable {
                 Thread workerThread = worker.thread;
                 if (workerThread != null && Thread.currentThread() != workerThread) {
                     if (channel.writeTaskInTaskQueue.compareAndSet(false, true)) {
-                        worker.taskQueue.offer(channel.writeTask);
+                        worker.writeTaskQueue.offer(channel.writeTask);
                     }
                     if (worker.wakenUp.compareAndSet(false, true)) {
                         worker.selector.wakeup();
@@ -434,11 +415,11 @@ class NioWorker implements Runnable {
         int bufIdx;
 
         synchronized (channel.writeLock) {
-            FastQueue<MessageEvent> internalWriteBuffer = channel.writeBuffer;
+            FastQueue<MessageEvent> writeBuffer = channel.writeBuffer;
             evt = channel.currentWriteEvent;
             for (;;) {
                 if (evt == null) {
-                    evt = internalWriteBuffer.poll();
+                    evt = writeBuffer.poll();
                     if (evt == null) {
                         channel.currentWriteEvent = null;
                         removeOpWrite = true;
@@ -510,11 +491,11 @@ class NioWorker implements Runnable {
         int writtenBytes = 0;
 
         synchronized (channel.writeLock) {
-            FastQueue<MessageEvent> internalWriteBuffer = channel.writeBuffer;
+            FastQueue<MessageEvent> writeBuffer = channel.writeBuffer;
             evt = channel.currentWriteEvent;
             for (;;) {
                 if (evt == null) {
-                    evt = internalWriteBuffer.poll();
+                    evt = writeBuffer.poll();
                     if (evt == null) {
                         channel.currentWriteEvent = null;
                         removeOpWrite = true;
@@ -758,9 +739,9 @@ class NioWorker implements Runnable {
                 fireExceptionCaught(channel, cause);
             }
 
-            FastQueue<MessageEvent> internalWriteBuffer = channel.writeBuffer;
+            FastQueue<MessageEvent> writeBuffer = channel.writeBuffer;
             for (;;) {
-                evt = internalWriteBuffer.poll();
+                evt = writeBuffer.poll();
                 if (evt == null) {
                     break;
                 }
@@ -837,4 +818,42 @@ class NioWorker implements Runnable {
             fireExceptionCaught(channel, t);
         }
     }
+
+    private class RegisterTask implements Runnable {
+        private final Selector selector;
+        private final NioSocketChannel channel;
+        private final ChannelFuture future;
+        private final boolean server;
+
+        RegisterTask(
+                Selector selector,
+                NioSocketChannel channel, ChannelFuture future, boolean server) {
+
+            this.selector = selector;
+            this.channel = channel;
+            this.future = future;
+            this.server = server;
+        }
+
+        public void run() {
+            try {
+                channel.socket.register(selector, SelectionKey.OP_READ, channel);
+                if (future != null) {
+                    future.setSuccess();
+                }
+            } catch (ClosedChannelException e) {
+                future.setFailure(e);
+                throw new ChannelException(
+                        "Failed to register a socket to the selector.", e);
+            }
+
+            if (server) {
+                fireChannelOpen(channel);
+                fireChannelBound(channel, channel.getLocalAddress());
+            } else if (!((NioClientSocketChannel) channel).boundManually) {
+                fireChannelBound(channel, channel.getLocalAddress());
+            }
+            fireChannelConnected(channel, channel.getRemoteAddress());
+        }
+    }
 }

src/main/java/org/jboss/netty/util/FastQueue.java

@@ -71,6 +71,11 @@ public class FastQueue<E> {
         return null;
     }
 
+    public synchronized boolean isEmpty() {
+        return offeredElements == null &&
+               (drainedElements == null || drainedElements.isEmpty());
+    }
+
     @SuppressWarnings("unchecked")
     private E cast(Object o) {
         return (E) o;