You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@hbase.apache.org by bi...@apache.org on 2016/12/22 06:49:57 UTC

[2/4] hbase git commit: HBASE-17262 Refactor RpcServer so as to make it extendable and/or pluggable

http://git-wip-us.apache.org/repos/asf/hbase/blob/fc93de51/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerFactory.java
----------------------------------------------------------------------
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerFactory.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerFactory.java
new file mode 100644
index 0000000..7d91a2c
--- /dev/null
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerFactory.java
@@ -0,0 +1,58 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.ipc;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.Server;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.ipc.RpcServer.BlockingServiceAndInterface;
+import org.apache.hadoop.hbase.util.ReflectionUtils;
+
+@InterfaceAudience.Private
+public class RpcServerFactory {
+
+  public static final Log LOG = LogFactory.getLog(RpcServerFactory.class);
+
+  public static final String CUSTOM_RPC_SERVER_IMPL_CONF_KEY = "hbase.rpc.server.impl";
+
+  /**
+   * Private Constructor
+   */
+  private RpcServerFactory() {
+  }
+
+  public static RpcServer createRpcServer(final Server server, final String name,
+      final List<BlockingServiceAndInterface> services,
+      final InetSocketAddress bindAddress, Configuration conf,
+      RpcScheduler scheduler) throws IOException {
+    String rpcServerClass = conf.get(CUSTOM_RPC_SERVER_IMPL_CONF_KEY,
+        SimpleRpcServer.class.getName());
+    LOG.info("Use " + rpcServerClass + " rpc server");
+    return ReflectionUtils.instantiateWithCustomCtor(rpcServerClass,
+        new Class[] { Server.class, String.class, List.class,
+            InetSocketAddress.class, Configuration.class, RpcScheduler.class },
+        new Object[] { server, name, services, bindAddress, conf, scheduler });
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/hbase/blob/fc93de51/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleRpcServer.java
----------------------------------------------------------------------
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleRpcServer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleRpcServer.java
new file mode 100644
index 0000000..01d45cd
--- /dev/null
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/SimpleRpcServer.java
@@ -0,0 +1,1997 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.ipc;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.BindException;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.SocketException;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.channels.CancelledKeyException;
+import java.nio.channels.Channels;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.GatheringByteChannel;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
+import java.nio.channels.ServerSocketChannel;
+import java.nio.channels.SocketChannel;
+import java.nio.channels.WritableByteChannel;
+import java.security.PrivilegedExceptionAction;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.Timer;
+import java.util.TimerTask;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedDeque;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.LongAdder;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+import javax.security.sasl.Sasl;
+import javax.security.sasl.SaslException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.CellScanner;
+import org.apache.hadoop.hbase.DoNotRetryIOException;
+import org.apache.hadoop.hbase.HBaseIOException;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.Server;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+import org.apache.hadoop.hbase.client.VersionInfoUtil;
+import org.apache.hadoop.hbase.exceptions.RequestTooBigException;
+import org.apache.hadoop.hbase.io.ByteBufferOutputStream;
+import org.apache.hadoop.hbase.monitoring.MonitoredRPCHandler;
+import org.apache.hadoop.hbase.nio.ByteBuff;
+import org.apache.hadoop.hbase.nio.SingleByteBuff;
+import org.apache.hadoop.hbase.security.AccessDeniedException;
+import org.apache.hadoop.hbase.security.AuthMethod;
+import org.apache.hadoop.hbase.security.HBasePolicyProvider;
+import org.apache.hadoop.hbase.security.HBaseSaslRpcServer;
+import org.apache.hadoop.hbase.security.HBaseSaslRpcServer.SaslDigestCallbackHandler;
+import org.apache.hadoop.hbase.security.HBaseSaslRpcServer.SaslGssCallbackHandler;
+import org.apache.hadoop.hbase.security.SaslStatus;
+import org.apache.hadoop.hbase.security.SaslUtil;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.BlockingService;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.CodedInputStream;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.Descriptors.MethodDescriptor;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.Message;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.TextFormat;
+import org.apache.hadoop.hbase.shaded.com.google.protobuf.UnsafeByteOperations;
+import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.ConnectionHeader;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.RequestHeader;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.Pair;
+import org.apache.hadoop.hbase.util.Threads;
+import org.apache.hadoop.io.BytesWritable;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableUtils;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
+import org.apache.hadoop.security.authorize.AuthorizationException;
+import org.apache.hadoop.security.authorize.ProxyUsers;
+import org.apache.hadoop.security.authorize.ServiceAuthorizationManager;
+import org.apache.hadoop.security.token.SecretManager.InvalidToken;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.htrace.TraceInfo;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+
+/**
+ * The RPC server with native java NIO implementation deriving from Hadoop to
+ * host protobuf described Services. It's the original one before HBASE-17262,
+ * and the default RPC server for now.
+ *
+ * An RpcServer instance has a Listener that hosts the socket.  Listener has fixed number
+ * of Readers in an ExecutorPool, 10 by default.  The Listener does an accept and then
+ * round robin a Reader is chosen to do the read.  The reader is registered on Selector.  Read does
+ * total read off the channel and the parse from which it makes a Call.  The call is wrapped in a
+ * CallRunner and passed to the scheduler to be run.  Reader goes back to see if more to be done
+ * and loops till done.
+ *
+ * <p>Scheduler can be variously implemented but default simple scheduler has handlers to which it
+ * has given the queues into which calls (i.e. CallRunner instances) are inserted.  Handlers run
+ * taking from the queue.  They run the CallRunner#run method on each item gotten from queue
+ * and keep taking while the server is up.
+ *
+ * CallRunner#run executes the call.  When done, asks the included Call to put itself on new
+ * queue for Responder to pull from and return result to client.
+ *
+ * @see BlockingRpcClient
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class SimpleRpcServer extends RpcServer {
+
+  protected int port;                             // port we listen on
+  protected InetSocketAddress address;            // inet address we listen on
+  private int readThreads;                        // number of read threads
+
+  protected int socketSendBufferSize;
+  protected final long purgeTimeout;    // in milliseconds
+
+  // maintains the set of client connections and handles idle timeouts
+  private ConnectionManager connectionManager;
+  private Listener listener = null;
+  protected Responder responder = null;
+
+  /**
+   * Datastructure that holds all necessary to a method invocation and then afterward, carries
+   * the result.
+   */
+  @InterfaceStability.Evolving
+  public class Call extends RpcServer.Call {
+
+    protected Responder responder;
+
+    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="NP_NULL_ON_SOME_PATH",
+        justification="Can't figure why this complaint is happening... see below")
+    Call(int id, final BlockingService service, final MethodDescriptor md,
+        RequestHeader header, Message param, CellScanner cellScanner,
+        Connection connection, Responder responder, long size, TraceInfo tinfo,
+        final InetAddress remoteAddress, int timeout, CallCleanup reqCleanup) {
+      super(id, service, md, header, param, cellScanner, connection, size,
+          tinfo, remoteAddress, timeout, reqCleanup);
+      this.responder = responder;
+    }
+
+    /**
+     * Call is done. Execution happened and we returned results to client. It is now safe to
+     * cleanup.
+     */
+    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="IS2_INCONSISTENT_SYNC",
+        justification="Presume the lock on processing request held by caller is protection enough")
+    void done() {
+      super.done();
+      this.getConnection().decRpcCount(); // Say that we're done with this call.
+    }
+
+    @Override
+    public long disconnectSince() {
+      if (!getConnection().isConnectionOpen()) {
+        return System.currentTimeMillis() - timestamp;
+      } else {
+        return -1L;
+      }
+    }
+
+    public synchronized void sendResponseIfReady() throws IOException {
+      // set param null to reduce memory pressure
+      this.param = null;
+      this.responder.doRespond(this);
+    }
+
+    Connection getConnection() {
+      return (Connection) this.connection;
+    }
+
+  }
+
+  /** Listens on the socket. Creates jobs for the handler threads*/
+  private class Listener extends Thread {
+
+    private ServerSocketChannel acceptChannel = null; //the accept channel
+    private Selector selector = null; //the selector that we use for the server
+    private Reader[] readers = null;
+    private int currentReader = 0;
+    private final int readerPendingConnectionQueueLength;
+
+    private ExecutorService readPool;
+
+    public Listener(final String name) throws IOException {
+      super(name);
+      // The backlog of requests that we will have the serversocket carry.
+      int backlogLength = conf.getInt("hbase.ipc.server.listen.queue.size", 128);
+      readerPendingConnectionQueueLength =
+          conf.getInt("hbase.ipc.server.read.connection-queue.size", 100);
+      // Create a new server socket and set to non blocking mode
+      acceptChannel = ServerSocketChannel.open();
+      acceptChannel.configureBlocking(false);
+
+      // Bind the server socket to the binding addrees (can be different from the default interface)
+      bind(acceptChannel.socket(), bindAddress, backlogLength);
+      port = acceptChannel.socket().getLocalPort(); //Could be an ephemeral port
+      address = (InetSocketAddress)acceptChannel.socket().getLocalSocketAddress();
+      // create a selector;
+      selector = Selector.open();
+
+      readers = new Reader[readThreads];
+      // Why this executor thing? Why not like hadoop just start up all the threads? I suppose it
+      // has an advantage in that it is easy to shutdown the pool.
+      readPool = Executors.newFixedThreadPool(readThreads,
+        new ThreadFactoryBuilder().setNameFormat(
+          "RpcServer.reader=%d,bindAddress=" + bindAddress.getHostName() +
+          ",port=" + port).setDaemon(true)
+        .setUncaughtExceptionHandler(Threads.LOGGING_EXCEPTION_HANDLER).build());
+      for (int i = 0; i < readThreads; ++i) {
+        Reader reader = new Reader();
+        readers[i] = reader;
+        readPool.execute(reader);
+      }
+      LOG.info(getName() + ": started " + readThreads + " reader(s) listening on port=" + port);
+
+      // Register accepts on the server socket with the selector.
+      acceptChannel.register(selector, SelectionKey.OP_ACCEPT);
+      this.setName("RpcServer.listener,port=" + port);
+      this.setDaemon(true);
+    }
+
+
+    private class Reader implements Runnable {
+      final private LinkedBlockingQueue<Connection> pendingConnections;
+      private final Selector readSelector;
+
+      Reader() throws IOException {
+        this.pendingConnections =
+          new LinkedBlockingQueue<Connection>(readerPendingConnectionQueueLength);
+        this.readSelector = Selector.open();
+      }
+
+      @Override
+      public void run() {
+        try {
+          doRunLoop();
+        } finally {
+          try {
+            readSelector.close();
+          } catch (IOException ioe) {
+            LOG.error(getName() + ": error closing read selector in " + getName(), ioe);
+          }
+        }
+      }
+
+      private synchronized void doRunLoop() {
+        while (running) {
+          try {
+            // Consume as many connections as currently queued to avoid
+            // unbridled acceptance of connections that starves the select
+            int size = pendingConnections.size();
+            for (int i=size; i>0; i--) {
+              Connection conn = pendingConnections.take();
+              conn.channel.register(readSelector, SelectionKey.OP_READ, conn);
+            }
+            readSelector.select();
+            Iterator<SelectionKey> iter = readSelector.selectedKeys().iterator();
+            while (iter.hasNext()) {
+              SelectionKey key = iter.next();
+              iter.remove();
+              if (key.isValid()) {
+                if (key.isReadable()) {
+                  doRead(key);
+                }
+              }
+              key = null;
+            }
+          } catch (InterruptedException e) {
+            if (running) {                      // unexpected -- log it
+              LOG.info(Thread.currentThread().getName() + " unexpectedly interrupted", e);
+            }
+            return;
+          } catch (IOException ex) {
+            LOG.info(getName() + ": IOException in Reader", ex);
+          }
+        }
+      }
+
+      /**
+       * Updating the readSelector while it's being used is not thread-safe,
+       * so the connection must be queued.  The reader will drain the queue
+       * and update its readSelector before performing the next select
+       */
+      public void addConnection(Connection conn) throws IOException {
+        pendingConnections.add(conn);
+        readSelector.wakeup();
+      }
+    }
+
+    @Override
+    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="IS2_INCONSISTENT_SYNC",
+      justification="selector access is not synchronized; seems fine but concerned changing " +
+        "it will have per impact")
+    public void run() {
+      LOG.info(getName() + ": starting");
+      connectionManager.startIdleScan();
+      while (running) {
+        SelectionKey key = null;
+        try {
+          selector.select(); // FindBugs IS2_INCONSISTENT_SYNC
+          Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
+          while (iter.hasNext()) {
+            key = iter.next();
+            iter.remove();
+            try {
+              if (key.isValid()) {
+                if (key.isAcceptable())
+                  doAccept(key);
+              }
+            } catch (IOException ignored) {
+              if (LOG.isTraceEnabled()) LOG.trace("ignored", ignored);
+            }
+            key = null;
+          }
+        } catch (OutOfMemoryError e) {
+          if (errorHandler != null) {
+            if (errorHandler.checkOOME(e)) {
+              LOG.info(getName() + ": exiting on OutOfMemoryError");
+              closeCurrentConnection(key, e);
+              connectionManager.closeIdle(true);
+              return;
+            }
+          } else {
+            // we can run out of memory if we have too many threads
+            // log the event and sleep for a minute and give
+            // some thread(s) a chance to finish
+            LOG.warn(getName() + ": OutOfMemoryError in server select", e);
+            closeCurrentConnection(key, e);
+            connectionManager.closeIdle(true);
+            try {
+              Thread.sleep(60000);
+            } catch (InterruptedException ex) {
+              LOG.debug("Interrupted while sleeping");
+            }
+          }
+        } catch (Exception e) {
+          closeCurrentConnection(key, e);
+        }
+      }
+      LOG.info(getName() + ": stopping");
+      synchronized (this) {
+        try {
+          acceptChannel.close();
+          selector.close();
+        } catch (IOException ignored) {
+          if (LOG.isTraceEnabled()) LOG.trace("ignored", ignored);
+        }
+
+        selector= null;
+        acceptChannel= null;
+
+        // close all connections
+        connectionManager.stopIdleScan();
+        connectionManager.closeAll();
+      }
+    }
+
+    private void closeCurrentConnection(SelectionKey key, Throwable e) {
+      if (key != null) {
+        Connection c = (Connection)key.attachment();
+        if (c != null) {
+          closeConnection(c);
+          key.attach(null);
+        }
+      }
+    }
+
+    InetSocketAddress getAddress() {
+      return address;
+    }
+
+    void doAccept(SelectionKey key) throws InterruptedException, IOException, OutOfMemoryError {
+      ServerSocketChannel server = (ServerSocketChannel) key.channel();
+      SocketChannel channel;
+      while ((channel = server.accept()) != null) {
+        channel.configureBlocking(false);
+        channel.socket().setTcpNoDelay(tcpNoDelay);
+        channel.socket().setKeepAlive(tcpKeepAlive);
+        Reader reader = getReader();
+        Connection c = connectionManager.register(channel);
+        // If the connectionManager can't take it, close the connection.
+        if (c == null) {
+          if (channel.isOpen()) {
+            IOUtils.cleanup(null, channel);
+          }
+          continue;
+        }
+        key.attach(c);  // so closeCurrentConnection can get the object
+        reader.addConnection(c);
+      }
+    }
+
+    void doRead(SelectionKey key) throws InterruptedException {
+      int count;
+      Connection c = (Connection) key.attachment();
+      if (c == null) {
+        return;
+      }
+      c.setLastContact(System.currentTimeMillis());
+      try {
+        count = c.readAndProcess();
+      } catch (InterruptedException ieo) {
+        LOG.info(Thread.currentThread().getName() + ": readAndProcess caught InterruptedException", ieo);
+        throw ieo;
+      } catch (Exception e) {
+        if (LOG.isDebugEnabled()) {
+          LOG.debug(getName() + ": Caught exception while reading:", e);
+        }
+        count = -1; //so that the (count < 0) block is executed
+      }
+      if (count < 0) {
+        closeConnection(c);
+        c = null;
+      } else {
+        c.setLastContact(System.currentTimeMillis());
+      }
+    }
+
+    synchronized void doStop() {
+      if (selector != null) {
+        selector.wakeup();
+        Thread.yield();
+      }
+      if (acceptChannel != null) {
+        try {
+          acceptChannel.socket().close();
+        } catch (IOException e) {
+          LOG.info(getName() + ": exception in closing listener socket. " + e);
+        }
+      }
+      readPool.shutdownNow();
+    }
+
+    // The method that will return the next reader to work with
+    // Simplistic implementation of round robin for now
+    Reader getReader() {
+      currentReader = (currentReader + 1) % readers.length;
+      return readers[currentReader];
+    }
+  }
+
+  // Sends responses of RPC back to clients.
+  protected class Responder extends Thread {
+    private final Selector writeSelector;
+    private final Set<Connection> writingCons =
+        Collections.newSetFromMap(new ConcurrentHashMap<Connection, Boolean>());
+
+    Responder() throws IOException {
+      this.setName("RpcServer.responder");
+      this.setDaemon(true);
+      this.setUncaughtExceptionHandler(Threads.LOGGING_EXCEPTION_HANDLER);
+      writeSelector = Selector.open(); // create a selector
+    }
+
+    @Override
+    public void run() {
+      LOG.debug(getName() + ": starting");
+      try {
+        doRunLoop();
+      } finally {
+        LOG.info(getName() + ": stopping");
+        try {
+          writeSelector.close();
+        } catch (IOException ioe) {
+          LOG.error(getName() + ": couldn't close write selector", ioe);
+        }
+      }
+    }
+
+    /**
+     * Take the list of the connections that want to write, and register them
+     * in the selector.
+     */
+    private void registerWrites() {
+      Iterator<Connection> it = writingCons.iterator();
+      while (it.hasNext()) {
+        Connection c = it.next();
+        it.remove();
+        SelectionKey sk = c.channel.keyFor(writeSelector);
+        try {
+          if (sk == null) {
+            try {
+              c.channel.register(writeSelector, SelectionKey.OP_WRITE, c);
+            } catch (ClosedChannelException e) {
+              // ignore: the client went away.
+              if (LOG.isTraceEnabled()) LOG.trace("ignored", e);
+            }
+          } else {
+            sk.interestOps(SelectionKey.OP_WRITE);
+          }
+        } catch (CancelledKeyException e) {
+          // ignore: the client went away.
+          if (LOG.isTraceEnabled()) LOG.trace("ignored", e);
+        }
+      }
+    }
+
+    /**
+     * Add a connection to the list that want to write,
+     */
+    public void registerForWrite(Connection c) {
+      if (writingCons.add(c)) {
+        writeSelector.wakeup();
+      }
+    }
+
+    private void doRunLoop() {
+      long lastPurgeTime = 0;   // last check for old calls.
+      while (running) {
+        try {
+          registerWrites();
+          int keyCt = writeSelector.select(purgeTimeout);
+          if (keyCt == 0) {
+            continue;
+          }
+
+          Set<SelectionKey> keys = writeSelector.selectedKeys();
+          Iterator<SelectionKey> iter = keys.iterator();
+          while (iter.hasNext()) {
+            SelectionKey key = iter.next();
+            iter.remove();
+            try {
+              if (key.isValid() && key.isWritable()) {
+                doAsyncWrite(key);
+              }
+            } catch (IOException e) {
+              LOG.debug(getName() + ": asyncWrite", e);
+            }
+          }
+
+          lastPurgeTime = purge(lastPurgeTime);
+
+        } catch (OutOfMemoryError e) {
+          if (errorHandler != null) {
+            if (errorHandler.checkOOME(e)) {
+              LOG.info(getName() + ": exiting on OutOfMemoryError");
+              return;
+            }
+          } else {
+            //
+            // we can run out of memory if we have too many threads
+            // log the event and sleep for a minute and give
+            // some thread(s) a chance to finish
+            //
+            LOG.warn(getName() + ": OutOfMemoryError in server select", e);
+            try {
+              Thread.sleep(60000);
+            } catch (InterruptedException ex) {
+              LOG.debug("Interrupted while sleeping");
+              return;
+            }
+          }
+        } catch (Exception e) {
+          LOG.warn(getName() + ": exception in Responder " +
+              StringUtils.stringifyException(e), e);
+        }
+      }
+      LOG.info(getName() + ": stopped");
+    }
+
+    /**
+     * If there were some calls that have not been sent out for a
+     * long time, we close the connection.
+     * @return the time of the purge.
+     */
+    private long purge(long lastPurgeTime) {
+      long now = System.currentTimeMillis();
+      if (now < lastPurgeTime + purgeTimeout) {
+        return lastPurgeTime;
+      }
+
+      ArrayList<Connection> conWithOldCalls = new ArrayList<Connection>();
+      // get the list of channels from list of keys.
+      synchronized (writeSelector.keys()) {
+        for (SelectionKey key : writeSelector.keys()) {
+          Connection connection = (Connection) key.attachment();
+          if (connection == null) {
+            throw new IllegalStateException("Coding error: SelectionKey key without attachment.");
+          }
+          Call call = connection.responseQueue.peekFirst();
+          if (call != null && now > call.timestamp + purgeTimeout) {
+            conWithOldCalls.add(call.getConnection());
+          }
+        }
+      }
+
+      // Seems safer to close the connection outside of the synchronized loop...
+      for (Connection connection : conWithOldCalls) {
+        closeConnection(connection);
+      }
+
+      return now;
+    }
+
+    private void doAsyncWrite(SelectionKey key) throws IOException {
+      Connection connection = (Connection) key.attachment();
+      if (connection == null) {
+        throw new IOException("doAsyncWrite: no connection");
+      }
+      if (key.channel() != connection.channel) {
+        throw new IOException("doAsyncWrite: bad channel");
+      }
+
+      if (processAllResponses(connection)) {
+        try {
+          // We wrote everything, so we don't need to be told when the socket is ready for
+          //  write anymore.
+         key.interestOps(0);
+        } catch (CancelledKeyException e) {
+          /* The Listener/reader might have closed the socket.
+           * We don't explicitly cancel the key, so not sure if this will
+           * ever fire.
+           * This warning could be removed.
+           */
+          LOG.warn("Exception while changing ops : " + e);
+        }
+      }
+    }
+
+    /**
+     * Process the response for this call. You need to have the lock on
+     * {@link org.apache.hadoop.hbase.ipc.SimpleRpcServer.Connection#responseWriteLock}
+     *
+     * @param call the call
+     * @return true if we proceed the call fully, false otherwise.
+     * @throws IOException
+     */
+    private boolean processResponse(final Call call) throws IOException {
+      boolean error = true;
+      try {
+        // Send as much data as we can in the non-blocking fashion
+        long numBytes = channelWrite(call.getConnection().channel,
+            call.response);
+        if (numBytes < 0) {
+          throw new HBaseIOException("Error writing on the socket " +
+            "for the call:" + call.toShortString());
+        }
+        error = false;
+      } finally {
+        if (error) {
+          LOG.debug(getName() + call.toShortString() + ": output error -- closing");
+          // We will be closing this connection itself. Mark this call as done so that all the
+          // buffer(s) it got from pool can get released
+          call.done();
+          closeConnection(call.getConnection());
+        }
+      }
+
+      if (!call.response.hasRemaining()) {
+        call.done();
+        return true;
+      } else {
+        return false; // Socket can't take more, we will have to come back.
+      }
+    }
+
+    /**
+     * Process all the responses for this connection
+     *
+     * @return true if all the calls were processed or that someone else is doing it.
+     * false if there * is still some work to do. In this case, we expect the caller to
+     * delay us.
+     * @throws IOException
+     */
+    private boolean processAllResponses(final Connection connection) throws IOException {
+      // We want only one writer on the channel for a connection at a time.
+      connection.responseWriteLock.lock();
+      try {
+        for (int i = 0; i < 20; i++) {
+          // protection if some handlers manage to need all the responder
+          Call call = connection.responseQueue.pollFirst();
+          if (call == null) {
+            return true;
+          }
+          if (!processResponse(call)) {
+            connection.responseQueue.addFirst(call);
+            return false;
+          }
+        }
+      } finally {
+        connection.responseWriteLock.unlock();
+      }
+
+      return connection.responseQueue.isEmpty();
+    }
+
+    //
+    // Enqueue a response from the application.
+    //
+    void doRespond(Call call) throws IOException {
+      boolean added = false;
+
+      // If there is already a write in progress, we don't wait. This allows to free the handlers
+      //  immediately for other tasks.
+      if (call.getConnection().responseQueue.isEmpty()
+          && call.getConnection().responseWriteLock.tryLock()) {
+        try {
+          if (call.getConnection().responseQueue.isEmpty()) {
+            // If we're alone, we can try to do a direct call to the socket. It's
+            //  an optimisation to save on context switches and data transfer between cores..
+            if (processResponse(call)) {
+              return; // we're done.
+            }
+            // Too big to fit, putting ahead.
+            call.getConnection().responseQueue.addFirst(call);
+            added = true; // We will register to the selector later, outside of the lock.
+          }
+        } finally {
+          call.getConnection().responseWriteLock.unlock();
+        }
+      }
+
+      if (!added) {
+        call.getConnection().responseQueue.addLast(call);
+      }
+      call.responder.registerForWrite(call.getConnection());
+
+      // set the serve time when the response has to be sent later
+      call.timestamp = System.currentTimeMillis();
+    }
+  }
+
+  /** Reads calls from a connection and queues them for handling. */
+  @edu.umd.cs.findbugs.annotations.SuppressWarnings(
+      value="VO_VOLATILE_INCREMENT",
+      justification="False positive according to http://sourceforge.net/p/findbugs/bugs/1032/")
+  public class Connection extends RpcServer.Connection {
+
+    protected SocketChannel channel;
+    private ByteBuff data;
+    private ByteBuffer dataLengthBuffer;
+    protected final ConcurrentLinkedDeque<Call> responseQueue = new ConcurrentLinkedDeque<Call>();
+    private final Lock responseWriteLock = new ReentrantLock();
+    private LongAdder rpcCount = new LongAdder(); // number of outstanding rpcs
+    private long lastContact;
+    protected Socket socket;
+
+    private ByteBuffer unwrappedData;
+    // When is this set?  FindBugs wants to know!  Says NP
+    private ByteBuffer unwrappedDataLengthBuffer = ByteBuffer.allocate(4);
+
+    private final Call authFailedCall = new Call(AUTHORIZATION_FAILED_CALLID, null, null, null,
+        null, null, this, null, 0, null, null, 0, null);
+
+    private final Call saslCall = new Call(SASL_CALLID, null, null, null, null, null, this, null,
+        0, null, null, 0, null);
+
+    private final Call setConnectionHeaderResponseCall = new Call(CONNECTION_HEADER_RESPONSE_CALLID,
+        null, null, null, null, null, this, null, 0, null, null, 0, null);
+
+    public Connection(SocketChannel channel, long lastContact) {
+      super();
+      this.channel = channel;
+      this.lastContact = lastContact;
+      this.data = null;
+      this.dataLengthBuffer = ByteBuffer.allocate(4);
+      this.socket = channel.socket();
+      this.addr = socket.getInetAddress();
+      if (addr == null) {
+        this.hostAddress = "*Unknown*";
+      } else {
+        this.hostAddress = addr.getHostAddress();
+      }
+      this.remotePort = socket.getPort();
+      if (socketSendBufferSize != 0) {
+        try {
+          socket.setSendBufferSize(socketSendBufferSize);
+        } catch (IOException e) {
+          LOG.warn("Connection: unable to set socket send buffer size to " +
+                   socketSendBufferSize);
+        }
+      }
+    }
+
+    public void setLastContact(long lastContact) {
+      this.lastContact = lastContact;
+    }
+
+    public long getLastContact() {
+      return lastContact;
+    }
+
+    /* Return true if the connection has no outstanding rpc */
+    private boolean isIdle() {
+      return rpcCount.sum() == 0;
+    }
+
+    /* Decrement the outstanding RPC count */
+    protected void decRpcCount() {
+      rpcCount.decrement();
+    }
+
+    /* Increment the outstanding RPC count */
+    protected void incRpcCount() {
+      rpcCount.increment();
+    }
+
+    private void saslReadAndProcess(ByteBuff saslToken) throws IOException,
+        InterruptedException {
+      if (saslContextEstablished) {
+        if (LOG.isTraceEnabled())
+          LOG.trace("Have read input token of size " + saslToken.limit()
+              + " for processing by saslServer.unwrap()");
+
+        if (!useWrap) {
+          processOneRpc(saslToken);
+        } else {
+          byte[] b = saslToken.hasArray() ? saslToken.array() : saslToken.toBytes();
+          byte [] plaintextData;
+          if (useCryptoAesWrap) {
+            // unwrap with CryptoAES
+            plaintextData = cryptoAES.unwrap(b, 0, b.length);
+          } else {
+            plaintextData = saslServer.unwrap(b, 0, b.length);
+          }
+          processUnwrappedData(plaintextData);
+        }
+      } else {
+        byte[] replyToken;
+        try {
+          if (saslServer == null) {
+            switch (authMethod) {
+            case DIGEST:
+              if (secretManager == null) {
+                throw new AccessDeniedException(
+                    "Server is not configured to do DIGEST authentication.");
+              }
+              saslServer = Sasl.createSaslServer(AuthMethod.DIGEST
+                  .getMechanismName(), null, SaslUtil.SASL_DEFAULT_REALM,
+                  HBaseSaslRpcServer.getSaslProps(), new SaslDigestCallbackHandler(
+                      secretManager, this));
+              break;
+            default:
+              UserGroupInformation current = UserGroupInformation.getCurrentUser();
+              String fullName = current.getUserName();
+              if (LOG.isDebugEnabled()) {
+                LOG.debug("Kerberos principal name is " + fullName);
+              }
+              final String names[] = SaslUtil.splitKerberosName(fullName);
+              if (names.length != 3) {
+                throw new AccessDeniedException(
+                    "Kerberos principal name does NOT have the expected "
+                        + "hostname part: " + fullName);
+              }
+              current.doAs(new PrivilegedExceptionAction<Object>() {
+                @Override
+                public Object run() throws SaslException {
+                  saslServer = Sasl.createSaslServer(AuthMethod.KERBEROS
+                      .getMechanismName(), names[0], names[1],
+                      HBaseSaslRpcServer.getSaslProps(), new SaslGssCallbackHandler());
+                  return null;
+                }
+              });
+            }
+            if (saslServer == null)
+              throw new AccessDeniedException(
+                  "Unable to find SASL server implementation for "
+                      + authMethod.getMechanismName());
+            if (LOG.isDebugEnabled()) {
+              LOG.debug("Created SASL server with mechanism = " + authMethod.getMechanismName());
+            }
+          }
+          if (LOG.isDebugEnabled()) {
+            LOG.debug("Have read input token of size " + saslToken.limit()
+                + " for processing by saslServer.evaluateResponse()");
+          }
+          replyToken = saslServer
+              .evaluateResponse(saslToken.hasArray() ? saslToken.array() : saslToken.toBytes());
+        } catch (IOException e) {
+          IOException sendToClient = e;
+          Throwable cause = e;
+          while (cause != null) {
+            if (cause instanceof InvalidToken) {
+              sendToClient = (InvalidToken) cause;
+              break;
+            }
+            cause = cause.getCause();
+          }
+          doRawSaslReply(SaslStatus.ERROR, null, sendToClient.getClass().getName(),
+            sendToClient.getLocalizedMessage());
+          metrics.authenticationFailure();
+          String clientIP = this.toString();
+          // attempting user could be null
+          AUDITLOG.warn(AUTH_FAILED_FOR + clientIP + ":" + attemptingUser);
+          throw e;
+        }
+        if (replyToken != null) {
+          if (LOG.isDebugEnabled()) {
+            LOG.debug("Will send token of size " + replyToken.length
+                + " from saslServer.");
+          }
+          doRawSaslReply(SaslStatus.SUCCESS, new BytesWritable(replyToken), null,
+              null);
+        }
+        if (saslServer.isComplete()) {
+          String qop = (String) saslServer.getNegotiatedProperty(Sasl.QOP);
+          useWrap = qop != null && !"auth".equalsIgnoreCase(qop);
+          ugi = getAuthorizedUgi(saslServer.getAuthorizationID());
+          if (LOG.isDebugEnabled()) {
+            LOG.debug("SASL server context established. Authenticated client: "
+              + ugi + ". Negotiated QoP is "
+              + saslServer.getNegotiatedProperty(Sasl.QOP));
+          }
+          metrics.authenticationSuccess();
+          AUDITLOG.info(AUTH_SUCCESSFUL_FOR + ugi);
+          saslContextEstablished = true;
+        }
+      }
+    }
+
+    /**
+     * No protobuf encoding of raw sasl messages
+     */
+    private void doRawSaslReply(SaslStatus status, Writable rv,
+        String errorClass, String error) throws IOException {
+      ByteBufferOutputStream saslResponse = null;
+      DataOutputStream out = null;
+      try {
+        // In my testing, have noticed that sasl messages are usually
+        // in the ballpark of 100-200. That's why the initial capacity is 256.
+        saslResponse = new ByteBufferOutputStream(256);
+        out = new DataOutputStream(saslResponse);
+        out.writeInt(status.state); // write status
+        if (status == SaslStatus.SUCCESS) {
+          rv.write(out);
+        } else {
+          WritableUtils.writeString(out, errorClass);
+          WritableUtils.writeString(out, error);
+        }
+        saslCall.setSaslTokenResponse(saslResponse.getByteBuffer());
+        saslCall.responder = responder;
+        saslCall.sendResponseIfReady();
+      } finally {
+        if (saslResponse != null) {
+          saslResponse.close();
+        }
+        if (out != null) {
+          out.close();
+        }
+      }
+    }
+
+    /**
+     * Send the response for connection header
+     */
+    private void doConnectionHeaderResponse(byte[] wrappedCipherMetaData) throws IOException {
+      ByteBufferOutputStream response = null;
+      DataOutputStream out = null;
+      try {
+        response = new ByteBufferOutputStream(wrappedCipherMetaData.length + 4);
+        out = new DataOutputStream(response);
+        out.writeInt(wrappedCipherMetaData.length);
+        out.write(wrappedCipherMetaData);
+
+        setConnectionHeaderResponseCall.setConnectionHeaderResponse(response.getByteBuffer());
+        setConnectionHeaderResponseCall.responder = responder;
+        setConnectionHeaderResponseCall.sendResponseIfReady();
+      } finally {
+        if (out != null) {
+          out.close();
+        }
+        if (response != null) {
+          response.close();
+        }
+      }
+    }
+
+    private void disposeSasl() {
+      if (saslServer != null) {
+        try {
+          saslServer.dispose();
+          saslServer = null;
+        } catch (SaslException ignored) {
+          // Ignored. This is being disposed of anyway.
+        }
+      }
+    }
+
+    private int readPreamble() throws IOException {
+      int count;
+      // Check for 'HBas' magic.
+      this.dataLengthBuffer.flip();
+      if (!Arrays.equals(HConstants.RPC_HEADER, dataLengthBuffer.array())) {
+        return doBadPreambleHandling("Expected HEADER=" +
+            Bytes.toStringBinary(HConstants.RPC_HEADER) +
+            " but received HEADER=" + Bytes.toStringBinary(dataLengthBuffer.array()) +
+            " from " + toString());
+      }
+      // Now read the next two bytes, the version and the auth to use.
+      ByteBuffer versionAndAuthBytes = ByteBuffer.allocate(2);
+      count = channelRead(channel, versionAndAuthBytes);
+      if (count < 0 || versionAndAuthBytes.remaining() > 0) {
+        return count;
+      }
+      int version = versionAndAuthBytes.get(0);
+      byte authbyte = versionAndAuthBytes.get(1);
+      this.authMethod = AuthMethod.valueOf(authbyte);
+      if (version != CURRENT_VERSION) {
+        String msg = getFatalConnectionString(version, authbyte);
+        return doBadPreambleHandling(msg, new WrongVersionException(msg));
+      }
+      if (authMethod == null) {
+        String msg = getFatalConnectionString(version, authbyte);
+        return doBadPreambleHandling(msg, new BadAuthException(msg));
+      }
+      if (isSecurityEnabled && authMethod == AuthMethod.SIMPLE) {
+        if (allowFallbackToSimpleAuth) {
+          metrics.authenticationFallback();
+          authenticatedWithFallback = true;
+        } else {
+          AccessDeniedException ae = new AccessDeniedException("Authentication is required");
+          setupResponse(authFailedResponse, authFailedCall, ae, ae.getMessage());
+          responder.doRespond(authFailedCall);
+          throw ae;
+        }
+      }
+      if (!isSecurityEnabled && authMethod != AuthMethod.SIMPLE) {
+        doRawSaslReply(SaslStatus.SUCCESS, new IntWritable(
+            SaslUtil.SWITCH_TO_SIMPLE_AUTH), null, null);
+        authMethod = AuthMethod.SIMPLE;
+        // client has already sent the initial Sasl message and we
+        // should ignore it. Both client and server should fall back
+        // to simple auth from now on.
+        skipInitialSaslHandshake = true;
+      }
+      if (authMethod != AuthMethod.SIMPLE) {
+        useSasl = true;
+      }
+
+      dataLengthBuffer.clear();
+      connectionPreambleRead = true;
+      return count;
+    }
+
+    private int read4Bytes() throws IOException {
+      if (this.dataLengthBuffer.remaining() > 0) {
+        return channelRead(channel, this.dataLengthBuffer);
+      } else {
+        return 0;
+      }
+    }
+
+    /**
+     * Read off the wire. If there is not enough data to read, update the connection state with
+     *  what we have and returns.
+     * @return Returns -1 if failure (and caller will close connection), else zero or more.
+     * @throws IOException
+     * @throws InterruptedException
+     */
+    public int readAndProcess() throws IOException, InterruptedException {
+      // Try and read in an int.  If new connection, the int will hold the 'HBas' HEADER.  If it
+      // does, read in the rest of the connection preamble, the version and the auth method.
+      // Else it will be length of the data to read (or -1 if a ping).  We catch the integer
+      // length into the 4-byte this.dataLengthBuffer.
+      int count = read4Bytes();
+      if (count < 0 || dataLengthBuffer.remaining() > 0) {
+        return count;
+      }
+
+      // If we have not read the connection setup preamble, look to see if that is on the wire.
+      if (!connectionPreambleRead) {
+        count = readPreamble();
+        if (!connectionPreambleRead) {
+          return count;
+        }
+
+        count = read4Bytes();
+        if (count < 0 || dataLengthBuffer.remaining() > 0) {
+          return count;
+        }
+      }
+
+      // We have read a length and we have read the preamble.  It is either the connection header
+      // or it is a request.
+      if (data == null) {
+        dataLengthBuffer.flip();
+        int dataLength = dataLengthBuffer.getInt();
+        if (dataLength == RpcClient.PING_CALL_ID) {
+          if (!useWrap) { //covers the !useSasl too
+            dataLengthBuffer.clear();
+            return 0;  //ping message
+          }
+        }
+        if (dataLength < 0) { // A data length of zero is legal.
+          throw new DoNotRetryIOException("Unexpected data length "
+              + dataLength + "!! from " + getHostAddress());
+        }
+
+        if (dataLength > maxRequestSize) {
+          String msg = "RPC data length of " + dataLength + " received from "
+              + getHostAddress() + " is greater than max allowed "
+              + maxRequestSize + ". Set \"" + MAX_REQUEST_SIZE
+              + "\" on server to override this limit (not recommended)";
+          LOG.warn(msg);
+
+          if (connectionHeaderRead && connectionPreambleRead) {
+            incRpcCount();
+            // Construct InputStream for the non-blocking SocketChannel
+            // We need the InputStream because we want to read only the request header
+            // instead of the whole rpc.
+            ByteBuffer buf = ByteBuffer.allocate(1);
+            InputStream is = new InputStream() {
+              @Override
+              public int read() throws IOException {
+                channelRead(channel, buf);
+                buf.flip();
+                int x = buf.get();
+                buf.flip();
+                return x;
+              }
+            };
+            CodedInputStream cis = CodedInputStream.newInstance(is);
+            int headerSize = cis.readRawVarint32();
+            Message.Builder builder = RequestHeader.newBuilder();
+            ProtobufUtil.mergeFrom(builder, cis, headerSize);
+            RequestHeader header = (RequestHeader) builder.build();
+
+            // Notify the client about the offending request
+            Call reqTooBig = new Call(header.getCallId(), this.service, null, null, null,
+                null, this, responder, 0, null, this.addr, 0, null);
+            metrics.exception(REQUEST_TOO_BIG_EXCEPTION);
+            // Make sure the client recognizes the underlying exception
+            // Otherwise, throw a DoNotRetryIOException.
+            if (VersionInfoUtil.hasMinimumVersion(connectionHeader.getVersionInfo(),
+                RequestTooBigException.MAJOR_VERSION, RequestTooBigException.MINOR_VERSION)) {
+              setupResponse(null, reqTooBig, REQUEST_TOO_BIG_EXCEPTION, msg);
+            } else {
+              setupResponse(null, reqTooBig, new DoNotRetryIOException(), msg);
+            }
+            // We are going to close the connection, make sure we process the response
+            // before that. In rare case when this fails, we still close the connection.
+            responseWriteLock.lock();
+            responder.processResponse(reqTooBig);
+            responseWriteLock.unlock();
+          }
+          // Close the connection
+          return -1;
+        }
+
+        // Initialize this.data with a ByteBuff.
+        // This call will allocate a ByteBuff to read request into and assign to this.data
+        // Also when we use some buffer(s) from pool, it will create a CallCleanup instance also and
+        // assign to this.callCleanup
+        initByteBuffToReadInto(dataLength);
+
+        // Increment the rpc count. This counter will be decreased when we write
+        //  the response.  If we want the connection to be detected as idle properly, we
+        //  need to keep the inc / dec correct.
+        incRpcCount();
+      }
+
+      count = channelDataRead(channel, data);
+
+      if (count >= 0 && data.remaining() == 0) { // count==0 if dataLength == 0
+        process();
+      }
+
+      return count;
+    }
+
+    // It creates the ByteBuff and CallCleanup and assign to Connection instance.
+    private void initByteBuffToReadInto(int length) {
+      // We create random on heap buffers are read into those when
+      // 1. ByteBufferPool is not there.
+      // 2. When the size of the req is very small. Using a large sized (64 KB) buffer from pool is
+      // waste then. Also if all the reqs are of this size, we will be creating larger sized
+      // buffers and pool them permanently. This include Scan/Get request and DDL kind of reqs like
+      // RegionOpen.
+      // 3. If it is an initial handshake signal or initial connection request. Any way then
+      // condition 2 itself will match
+      // 4. When SASL use is ON.
+      if (reservoir == null || skipInitialSaslHandshake || !connectionHeaderRead || useSasl
+          || length < minSizeForReservoirUse) {
+        this.data = new SingleByteBuff(ByteBuffer.allocate(length));
+      } else {
+        Pair<ByteBuff, CallCleanup> pair = RpcServer.allocateByteBuffToReadInto(reservoir,
+            minSizeForReservoirUse, length);
+        this.data = pair.getFirst();
+        this.callCleanup = pair.getSecond();
+      }
+    }
+
+    protected int channelDataRead(ReadableByteChannel channel, ByteBuff buf) throws IOException {
+      int count = buf.read(channel);
+      if (count > 0) {
+        metrics.receivedBytes(count);
+      }
+      return count;
+    }
+
+    /**
+     * Process the data buffer and clean the connection state for the next call.
+     */
+    private void process() throws IOException, InterruptedException {
+      data.rewind();
+      try {
+        if (skipInitialSaslHandshake) {
+          skipInitialSaslHandshake = false;
+          return;
+        }
+
+        if (useSasl) {
+          saslReadAndProcess(data);
+        } else {
+          processOneRpc(data);
+        }
+
+      } finally {
+        dataLengthBuffer.clear(); // Clean for the next call
+        data = null; // For the GC
+        this.callCleanup = null;
+      }
+    }
+
+    private int doBadPreambleHandling(final String msg) throws IOException {
+      return doBadPreambleHandling(msg, new FatalConnectionException(msg));
+    }
+
+    private int doBadPreambleHandling(final String msg, final Exception e) throws IOException {
+      LOG.warn(msg);
+      Call fakeCall = new Call(-1, null, null, null, null, null, this, responder, -1, null, null, 0,
+          null);
+      setupResponse(null, fakeCall, e, msg);
+      responder.doRespond(fakeCall);
+      // Returning -1 closes out the connection.
+      return -1;
+    }
+
+    // Reads the connection header following version
+    private void processConnectionHeader(ByteBuff buf) throws IOException {
+      if (buf.hasArray()) {
+        this.connectionHeader = ConnectionHeader.parseFrom(buf.array());
+      } else {
+        CodedInputStream cis = UnsafeByteOperations
+            .unsafeWrap(new ByteBuffByteInput(buf, 0, buf.limit()), 0, buf.limit()).newCodedInput();
+        cis.enableAliasing(true);
+        this.connectionHeader = ConnectionHeader.parseFrom(cis);
+      }
+      String serviceName = connectionHeader.getServiceName();
+      if (serviceName == null) throw new EmptyServiceNameException();
+      this.service = getService(services, serviceName);
+      if (this.service == null) throw new UnknownServiceException(serviceName);
+      setupCellBlockCodecs(this.connectionHeader);
+      RPCProtos.ConnectionHeaderResponse.Builder chrBuilder =
+          RPCProtos.ConnectionHeaderResponse.newBuilder();
+      setupCryptoCipher(this.connectionHeader, chrBuilder);
+      responseConnectionHeader(chrBuilder);
+      UserGroupInformation protocolUser = createUser(connectionHeader);
+      if (!useSasl) {
+        ugi = protocolUser;
+        if (ugi != null) {
+          ugi.setAuthenticationMethod(AuthMethod.SIMPLE.authenticationMethod);
+        }
+        // audit logging for SASL authenticated users happens in saslReadAndProcess()
+        if (authenticatedWithFallback) {
+          LOG.warn("Allowed fallback to SIMPLE auth for " + ugi
+              + " connecting from " + getHostAddress());
+        }
+        AUDITLOG.info(AUTH_SUCCESSFUL_FOR + ugi);
+      } else {
+        // user is authenticated
+        ugi.setAuthenticationMethod(authMethod.authenticationMethod);
+        //Now we check if this is a proxy user case. If the protocol user is
+        //different from the 'user', it is a proxy user scenario. However,
+        //this is not allowed if user authenticated with DIGEST.
+        if ((protocolUser != null)
+            && (!protocolUser.getUserName().equals(ugi.getUserName()))) {
+          if (authMethod == AuthMethod.DIGEST) {
+            // Not allowed to doAs if token authentication is used
+            throw new AccessDeniedException("Authenticated user (" + ugi
+                + ") doesn't match what the client claims to be ("
+                + protocolUser + ")");
+          } else {
+            // Effective user can be different from authenticated user
+            // for simple auth or kerberos auth
+            // The user is the real user. Now we create a proxy user
+            UserGroupInformation realUser = ugi;
+            ugi = UserGroupInformation.createProxyUser(protocolUser
+                .getUserName(), realUser);
+            // Now the user is a proxy user, set Authentication method Proxy.
+            ugi.setAuthenticationMethod(AuthenticationMethod.PROXY);
+          }
+        }
+      }
+      if (connectionHeader.hasVersionInfo()) {
+        // see if this connection will support RetryImmediatelyException
+        retryImmediatelySupported = VersionInfoUtil.hasMinimumVersion(getVersionInfo(), 1, 2);
+
+        AUDITLOG.info("Connection from " + this.hostAddress + " port: " + this.remotePort
+            + " with version info: "
+            + TextFormat.shortDebugString(connectionHeader.getVersionInfo()));
+      } else {
+        AUDITLOG.info("Connection from " + this.hostAddress + " port: " + this.remotePort
+            + " with unknown version info");
+      }
+    }
+
+    private void responseConnectionHeader(RPCProtos.ConnectionHeaderResponse.Builder chrBuilder)
+        throws FatalConnectionException {
+      // Response the connection header if Crypto AES is enabled
+      if (!chrBuilder.hasCryptoCipherMeta()) return;
+      try {
+        byte[] connectionHeaderResBytes = chrBuilder.build().toByteArray();
+        // encrypt the Crypto AES cipher meta data with sasl server, and send to client
+        byte[] unwrapped = new byte[connectionHeaderResBytes.length + 4];
+        Bytes.putBytes(unwrapped, 0, Bytes.toBytes(connectionHeaderResBytes.length), 0, 4);
+        Bytes.putBytes(unwrapped, 4, connectionHeaderResBytes, 0, connectionHeaderResBytes.length);
+
+        doConnectionHeaderResponse(saslServer.wrap(unwrapped, 0, unwrapped.length));
+      } catch (IOException ex) {
+        throw new UnsupportedCryptoException(ex.getMessage(), ex);
+      }
+    }
+
+    private void processUnwrappedData(byte[] inBuf) throws IOException,
+    InterruptedException {
+      ReadableByteChannel ch = Channels.newChannel(new ByteArrayInputStream(inBuf));
+      // Read all RPCs contained in the inBuf, even partial ones
+      while (true) {
+        int count;
+        if (unwrappedDataLengthBuffer.remaining() > 0) {
+          count = channelRead(ch, unwrappedDataLengthBuffer);
+          if (count <= 0 || unwrappedDataLengthBuffer.remaining() > 0)
+            return;
+        }
+
+        if (unwrappedData == null) {
+          unwrappedDataLengthBuffer.flip();
+          int unwrappedDataLength = unwrappedDataLengthBuffer.getInt();
+
+          if (unwrappedDataLength == RpcClient.PING_CALL_ID) {
+            if (LOG.isDebugEnabled())
+              LOG.debug("Received ping message");
+            unwrappedDataLengthBuffer.clear();
+            continue; // ping message
+          }
+          unwrappedData = ByteBuffer.allocate(unwrappedDataLength);
+        }
+
+        count = channelRead(ch, unwrappedData);
+        if (count <= 0 || unwrappedData.remaining() > 0)
+          return;
+
+        if (unwrappedData.remaining() == 0) {
+          unwrappedDataLengthBuffer.clear();
+          unwrappedData.flip();
+          processOneRpc(new SingleByteBuff(unwrappedData));
+          unwrappedData = null;
+        }
+      }
+    }
+
+    private void processOneRpc(ByteBuff buf) throws IOException, InterruptedException {
+      if (connectionHeaderRead) {
+        processRequest(buf);
+      } else {
+        processConnectionHeader(buf);
+        this.connectionHeaderRead = true;
+        if (!authorizeConnection()) {
+          // Throw FatalConnectionException wrapping ACE so client does right thing and closes
+          // down the connection instead of trying to read non-existent retun.
+          throw new AccessDeniedException("Connection from " + this + " for service " +
+            connectionHeader.getServiceName() + " is unauthorized for user: " + ugi);
+        }
+        this.user = userProvider.create(this.ugi);
+      }
+    }
+
+    /**
+     * @param buf Has the request header and the request param and optionally encoded data buffer
+     * all in this one array.
+     * @throws IOException
+     * @throws InterruptedException
+     */
+    protected void processRequest(ByteBuff buf) throws IOException, InterruptedException {
+      long totalRequestSize = buf.limit();
+      int offset = 0;
+      // Here we read in the header.  We avoid having pb
+      // do its default 4k allocation for CodedInputStream.  We force it to use backing array.
+      CodedInputStream cis;
+      if (buf.hasArray()) {
+        cis = UnsafeByteOperations.unsafeWrap(buf.array(), 0, buf.limit()).newCodedInput();
+      } else {
+        cis = UnsafeByteOperations
+            .unsafeWrap(new ByteBuffByteInput(buf, 0, buf.limit()), 0, buf.limit()).newCodedInput();
+      }
+      cis.enableAliasing(true);
+      int headerSize = cis.readRawVarint32();
+      offset = cis.getTotalBytesRead();
+      Message.Builder builder = RequestHeader.newBuilder();
+      ProtobufUtil.mergeFrom(builder, cis, headerSize);
+      RequestHeader header = (RequestHeader) builder.build();
+      offset += headerSize;
+      int id = header.getCallId();
+      if (LOG.isTraceEnabled()) {
+        LOG.trace("RequestHeader " + TextFormat.shortDebugString(header) +
+          " totalRequestSize: " + totalRequestSize + " bytes");
+      }
+      // Enforcing the call queue size, this triggers a retry in the client
+      // This is a bit late to be doing this check - we have already read in the total request.
+      if ((totalRequestSize + callQueueSizeInBytes.sum()) > maxQueueSizeInBytes) {
+        final Call callTooBig =
+          new Call(id, this.service, null, null, null, null, this,
+            responder, totalRequestSize, null, null, 0, this.callCleanup);
+        ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
+        metrics.exception(CALL_QUEUE_TOO_BIG_EXCEPTION);
+        setupResponse(responseBuffer, callTooBig, CALL_QUEUE_TOO_BIG_EXCEPTION,
+            "Call queue is full on " + server.getServerName() +
+                ", is hbase.ipc.server.max.callqueue.size too small?");
+        responder.doRespond(callTooBig);
+        return;
+      }
+      MethodDescriptor md = null;
+      Message param = null;
+      CellScanner cellScanner = null;
+      try {
+        if (header.hasRequestParam() && header.getRequestParam()) {
+          md = this.service.getDescriptorForType().findMethodByName(header.getMethodName());
+          if (md == null) throw new UnsupportedOperationException(header.getMethodName());
+          builder = this.service.getRequestPrototype(md).newBuilderForType();
+          cis.resetSizeCounter();
+          int paramSize = cis.readRawVarint32();
+          offset += cis.getTotalBytesRead();
+          if (builder != null) {
+            ProtobufUtil.mergeFrom(builder, cis, paramSize);
+            param = builder.build();
+          }
+          offset += paramSize;
+        } else {
+          // currently header must have request param, so we directly throw exception here
+          String msg = "Invalid request header: " + TextFormat.shortDebugString(header)
+              + ", should have param set in it";
+          LOG.warn(msg);
+          throw new DoNotRetryIOException(msg);
+        }
+        if (header.hasCellBlockMeta()) {
+          buf.position(offset);
+          ByteBuff dup = buf.duplicate();
+          dup.limit(offset + header.getCellBlockMeta().getLength());
+          cellScanner = cellBlockBuilder.createCellScannerReusingBuffers(this.codec,
+              this.compressionCodec, dup);
+        }
+      } catch (Throwable t) {
+        InetSocketAddress address = getListenerAddress();
+        String msg = (address != null ? address : "(channel closed)") +
+            " is unable to read call parameter from client " + getHostAddress();
+        LOG.warn(msg, t);
+
+        metrics.exception(t);
+
+        // probably the hbase hadoop version does not match the running hadoop version
+        if (t instanceof LinkageError) {
+          t = new DoNotRetryIOException(t);
+        }
+        // If the method is not present on the server, do not retry.
+        if (t instanceof UnsupportedOperationException) {
+          t = new DoNotRetryIOException(t);
+        }
+
+        final Call readParamsFailedCall =
+          new Call(id, this.service, null, null, null, null, this,
+            responder, totalRequestSize, null, null, 0, this.callCleanup);
+        ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
+        setupResponse(responseBuffer, readParamsFailedCall, t,
+          msg + "; " + t.getMessage());
+        responder.doRespond(readParamsFailedCall);
+        return;
+      }
+
+      TraceInfo traceInfo = header.hasTraceInfo()
+          ? new TraceInfo(header.getTraceInfo().getTraceId(), header.getTraceInfo().getParentId())
+          : null;
+      int timeout = 0;
+      if (header.hasTimeout() && header.getTimeout() > 0){
+        timeout = Math.max(minClientRequestTimeout, header.getTimeout());
+      }
+      Call call = new Call(id, this.service, md, header, param, cellScanner, this, responder,
+          totalRequestSize, traceInfo, this.addr, timeout, this.callCleanup);
+
+      if (!scheduler.dispatch(new CallRunner(SimpleRpcServer.this, call))) {
+        callQueueSizeInBytes.add(-1 * call.getSize());
+
+        ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
+        metrics.exception(CALL_QUEUE_TOO_BIG_EXCEPTION);
+        setupResponse(responseBuffer, call, CALL_QUEUE_TOO_BIG_EXCEPTION,
+            "Call queue is full on " + server.getServerName() +
+                ", too many items queued ?");
+        responder.doRespond(call);
+      }
+    }
+
+    private boolean authorizeConnection() throws IOException {
+      try {
+        // If auth method is DIGEST, the token was obtained by the
+        // real user for the effective user, therefore not required to
+        // authorize real user. doAs is allowed only for simple or kerberos
+        // authentication
+        if (ugi != null && ugi.getRealUser() != null
+            && (authMethod != AuthMethod.DIGEST)) {
+          ProxyUsers.authorize(ugi, this.getHostAddress(), conf);
+        }
+        authorize(ugi, connectionHeader, getHostInetAddress());
+        metrics.authorizationSuccess();
+      } catch (AuthorizationException ae) {
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Connection authorization failed: " + ae.getMessage(), ae);
+        }
+        metrics.authorizationFailure();
+        setupResponse(authFailedResponse, authFailedCall,
+          new AccessDeniedException(ae), ae.getMessage());
+        responder.doRespond(authFailedCall);
+        return false;
+      }
+      return true;
+    }
+
+    protected synchronized void close() {
+      disposeSasl();
+      data = null;
+      callCleanup = null;
+      if (!channel.isOpen())
+        return;
+      try {socket.shutdownOutput();} catch(Exception ignored) {
+        if (LOG.isTraceEnabled()) {
+          LOG.trace("Ignored exception", ignored);
+        }
+      }
+      if (channel.isOpen()) {
+        try {channel.close();} catch(Exception ignored) {}
+      }
+      try {
+        socket.close();
+      } catch(Exception ignored) {
+        if (LOG.isTraceEnabled()) {
+          LOG.trace("Ignored exception", ignored);
+        }
+      }
+    }
+
+    @Override
+    public boolean isConnectionOpen() {
+      return channel.isOpen();
+    }
+  }
+
+
+  /**
+   * Constructs a server listening on the named port and address.
+   * @param server hosting instance of {@link Server}. We will do authentications if an
+   * instance else pass null for no authentication check.
+   * @param name Used keying this rpc servers' metrics and for naming the Listener thread.
+   * @param services A list of services.
+   * @param bindAddress Where to listen
+   * @param conf
+   * @param scheduler
+   */
+  public SimpleRpcServer(final Server server, final String name,
+      final List<BlockingServiceAndInterface> services,
+      final InetSocketAddress bindAddress, Configuration conf,
+      RpcScheduler scheduler)
+      throws IOException {
+    super(server, name, services, bindAddress, conf, scheduler);
+    this.socketSendBufferSize = 0;
+    this.readThreads = conf.getInt("hbase.ipc.server.read.threadpool.size", 10);
+    this.purgeTimeout = conf.getLong("hbase.ipc.client.call.purge.timeout",
+      2 * HConstants.DEFAULT_HBASE_RPC_TIMEOUT);
+
+    // Start the listener here and let it bind to the port
+    listener = new Listener(name);
+    this.port = listener.getAddress().getPort();
+
+    // Create the responder here
+    responder = new Responder();
+    connectionManager = new ConnectionManager();
+    initReconfigurable(conf);
+
+    this.scheduler.init(new RpcSchedulerContext(this));
+  }
+
+  /**
+   * Subclasses of HBaseServer can override this to provide their own
+   * Connection implementations.
+   */
+  protected Connection getConnection(SocketChannel channel, long time) {
+    return new Connection(channel, time);
+  }
+
+  /**
+   * Setup response for the RPC Call.
+   *
+   * @param response buffer to serialize the response into
+   * @param call {@link Call} to which we are setting up the response
+   * @param error error message, if the call failed
+   * @throws IOException
+   */
+  private void setupResponse(ByteArrayOutputStream response, Call call, Throwable t, String error)
+  throws IOException {
+    if (response != null) response.reset();
+    call.setResponse(null, null, t, error);
+  }
+
+  protected void closeConnection(Connection connection) {
+    connectionManager.close(connection);
+  }
+
+  /** Sets the socket buffer size used for responding to RPCs.
+   * @param size send size
+   */
+  @Override
+  public void setSocketSendBufSize(int size) { this.socketSendBufferSize = size; }
+
+  /** Starts the service.  Must be called before any calls will be handled. */
+  @Override
+  public synchronized void start() {
+    if (started) return;
+    authTokenSecretMgr = createSecretManager();
+    if (authTokenSecretMgr != null) {
+      setSecretManager(authTokenSecretMgr);
+      authTokenSecretMgr.start();
+    }
+    this.authManager = new ServiceAuthorizationManager();
+    HBasePolicyProvider.init(conf, authManager);
+    responder.start();
+    listener.start();
+    scheduler.start();
+    started = true;
+  }
+
+  /** Stops the service.  No new calls will be handled after this is called. */
+  @Override
+  public synchronized void stop() {
+    LOG.info("Stopping server on " + port);
+    running = false;
+    if (authTokenSecretMgr != null) {
+      authTokenSecretMgr.stop();
+      authTokenSecretMgr = null;
+    }
+    listener.interrupt();
+    listener.doStop();
+    responder.interrupt();
+    scheduler.stop();
+    notifyAll();
+  }
+
+  /** Wait for the server to be stopped.
+   * Does not wait for all subthreads to finish.
+   *  See {@link #stop()}.
+   * @throws InterruptedException e
+   */
+  @Override
+  public synchronized void join() throws InterruptedException {
+    while (running) {
+      wait();
+    }
+  }
+
+  /**
+   * Return the socket (ip+port) on which the RPC server is listening to. May return null if
+   * the listener channel is closed.
+   * @return the socket (ip+port) on which the RPC server is listening to, or null if this
+   * information cannot be determined
+   */
+  @Override
+  public synchronized InetSocketAddress getListenerAddress() {
+    if (listener == null) {
+      return null;
+    }
+    return listener.getAddress();
+  }
+
+  public Pair<Message, CellScanner> call(BlockingService service, MethodDescriptor md,
+      Message param, CellScanner cellScanner, long receiveTime, MonitoredRPCHandler status)
+      throws IOException {
+    return call(service, md, param, cellScanner, receiveTime, status, System.currentTimeMillis(),0);
+  }
+
+  public Pair<Message, CellScanner> call(BlockingService service, MethodDescriptor md, Message param,
+      CellScanner cellScanner, long receiveTime, MonitoredRPCHandler status, long startTime,
+      int timeout)
+      throws IOException {
+    Call fakeCall = new Call(-1, service, md, null, param, cellScanner, null, null, -1, null, null, timeout,
+      null);
+    fakeCall.setReceiveTime(receiveTime);
+    return call(fakeCall, status);
+  }
+
+  /**
+   * When the read or write buffer size is larger than this limit, i/o will be
+   * done in chunks of this size. Most RPC requests and responses would be
+   * be smaller.
+   */
+  private static int NIO_BUFFER_LIMIT = 64 * 1024; //should not be more than 64KB.
+
+  /**
+   * This is a wrapper around {@link java.nio.channels.WritableByteChannel#write(java.nio.ByteBuffer)}.
+   * If the amount of data is large, it writes to channel in smaller chunks.
+   * This is to avoid jdk from creating many direct buffers as the size of
+   * buffer increases. This also minimizes extra copies in NIO layer
+   * as a result of multiple write operations required to write a large
+   * buffer.
+   *
+   * @param channel writable byte channel to write to
+   * @param bufferChain Chain of buffers to write
+   * @return number of bytes written
+   * @throws java.io.IOException e
+   * @see java.nio.channels.WritableByteChannel#write(java.nio.ByteBuffer)
+   */
+  protected long channelWrite(GatheringByteChannel channel, BufferChain bufferChain)
+  throws IOException {
+    long count =  bufferChain.write(channel, NIO_BUFFER_LIMIT);
+    if (count > 0) this.metrics.sentBytes(count);
+    return count;
+  }
+
+  /**
+   * This is a wrapper around {@link java.nio.channels.ReadableByteChannel#read(java.nio.ByteBuffer)}.
+   * If the amount of data is large, it writes to channel in smaller chunks.
+   * This is to avoid jdk from creating many direct buffers as the size of
+   * ByteBuffer increases. There should not be any performance degredation.
+   *
+   * @param channel writable byte channel to write on
+   * @param buffer buffer to write
+   * @return number of bytes written
+   * @throws java.io.IOException e
+   * @see java.nio.channels.ReadableByteChannel#read(java.nio.ByteBuffer)
+   */
+  protected int channelRead(ReadableByteChannel channel,
+                                   ByteBuffer buffer) throws IOException {
+
+    int count = (buffer.remaining() <= NIO_BUFFER_LIMIT) ?
+           channel.read(buffer) : channelIO(channel, null, buffer);
+    if (count > 0) {
+      metrics.receivedBytes(count);
+    }
+    return count;
+  }
+
+  /**
+   * Helper for {@link #channelRead(java.nio.channels.ReadableByteChannel, java.nio.ByteBuffer)}
+   * and {@link #channelWrite(GatheringByteChannel, BufferChain)}. Only
+   * one of readCh or writeCh should be non-null.
+   *
+   * @param readCh read channel
+   * @param writeCh write channel
+   * @param buf buffer to read or write into/out of
+   * @return bytes written
+   * @throws java.io.IOException e
+   * @see #channelRead(java.nio.channels.ReadableByteChannel, java.nio.ByteBuffer)
+   * @see #channelWrite(GatheringByteChannel, BufferChain)
+   */
+  protected static int channelIO(ReadableByteChannel readCh,
+                               WritableByteChannel writeCh,
+                               ByteBuffer buf) throws IOException {
+
+    int originalLimit = buf.limit();
+    int initialRemaining = buf.remaining();
+    int ret = 0;
+
+    while (buf.remaining() > 0) {
+      try {
+        int ioSize = Math.min(buf.remaining(), NIO_BUFFER_LIMIT);
+        buf.limit(buf.position() + ioSize);
+
+        ret = (readCh == null) ? writeCh.write(buf) : readCh.read(buf);
+
+        if (ret < ioSize) {
+          break;
+        }
+
+      } finally {
+        buf.limit(originalLimit);
+      }
+    }
+
+    int nBytes = initialRemaining - buf.remaining();
+    return (nBytes > 0) ? nBytes : ret;
+  }
+
+  /**
+   * A convenience method to bind to a given address and report
+   * better exceptions if the address is not a valid host.
+   * @param socket the socket to bind
+   * @param address the address to bind to
+   * @param backlog the number of connections allowed in the queue
+   * @throws BindException if the address can't be bound
+   * @throws UnknownHostException if the address isn't a valid host name
+   * @throws IOException other random errors from bind
+   */
+  public static void bind(ServerSocket socket, InetSocketAddress address,
+                          int backlog) throws IOException {
+    try {
+      socket.bind(address, backlog);
+    } catch (BindException e) {
+      BindException bindException =
+        new BindException("Problem binding to " + address + " : " +
+            e.getMessage());
+      bindException.initCause(e);
+      throw bindException;
+    } catch (SocketException e) {
+      // If they try to bind to a different host's address, give a better
+      // error message.
+      if ("Unresolved address".equals(e.getMessage())) {
+        throw new UnknownHostException("Invalid hostname for server: " +
+                                       address.getHostName());
+      }
+      throw e;
+    }
+  }
+
+  /**
+   * The number of open RPC conections
+   * @return the number of open rpc connections
+   */
+  public int getNumOpenConnections() {
+    return connectionManager.size();
+  }
+
+  private class ConnectionManager {
+    final private AtomicInteger count = new AtomicInteger();
+    final private Set<Connection> connections;
+
+    final private Timer idleScanTimer;
+    final private int idleScanThreshold;
+    final private int idleScanInterval;
+    final private int maxIdleTime;
+    final private int maxIdleToClose;
+
+    ConnectionManager() {
+      this.idleScanTimer = new Timer("RpcServer idle connection scanner for port " + port, true);
+      this.idleScanThreshold = conf.getInt("hbase.ipc.client.idlethreshold", 4000);
+      this.idleScanInterval =
+          conf.getInt("hbase.ipc.client.connection.idle-scan-interval.ms", 10000);
+      this.maxIdleTime = 2 * conf.getInt("hbase.ipc.client.connection.maxidletime", 10000);
+      this.maxIdleToClose = conf.getInt("hbase.ipc.client.kill.max", 10);
+      int handlerCount = conf.getInt(HConstants.REGION_SERVER_HANDLER_COUNT,
+          HConstants.DEFAULT_REGION_SERVER_HANDLER_COUNT);
+      int maxConnectionQueueSize =
+          handlerCount * conf.getInt("hbase.ipc.server.handler.queue.size", 100);
+      // create a set with concurrency -and- a thread-safe iterator, add 2
+      // for listener and idle closer threads
+      this.connections = Collections.newSetFromMap(
+          new ConcurrentHashMap<Connection,Boolean>(
+              maxConnectionQueueSize, 0.75f, readThreads+2));
+    }
+
+    private boolean add(Connection connection) {
+      boolean added = connections.add(connection);
+      if (added) {
+        count.getAndIncrement();
+      }
+      return added;
+    }
+
+    private boolean remove(Connection connection) {
+      boolean removed = connections.remove(connection);
+      if (removed) {
+        count.getAndDecrement();
+      }
+      return removed;
+    }
+
+    int size() {
+      return count.get();
+    }
+
+    Connection[] toArray() {
+      return connections.toArray(new Connection[0]);
+    }
+
+    Connection register(SocketChannel channel) {
+      Connection connection = getConnection(channel, System.currentTimeMillis());
+      add(connection);
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Server connection from " + connection +
+            "; connections=" + size() +
+            ", queued calls size (bytes)=" + callQueueSizeInBytes.sum() +
+            ", general queued calls=" + scheduler.getGeneralQueueLength() +
+            ", priority queued calls=" + scheduler.getPriorityQueueLength());
+      }
+      return connection;
+    }
+
+    boolean close(Connection connection) {
+      boolean exists = remove(connection);
+      if (exists) {
+        if (LOG.isDebugEnabled()) {
+          LOG.debug(Thread.currentThread().getName() +
+              ": disconnecting client " + connection +
+              ". Number of active connections: "+ size());
+        }
+        // only close if actually removed to avoid double-closing due
+        // to possible races
+        connection.close();
+      }
+      return exists;
+    }
+
+    // synch'ed to avoid explicit invocation upon OOM from colliding with
+    // timer task firing
+    synchronized void closeIdle(boolean scanAll) {
+      long minLastContact = System.currentTimeMillis() - maxIdleTime;
+      // concurrent iterator might miss new connections added
+      // during the iteration, but that's ok because they won't
+      // be idle yet anyway and will be caught on next scan
+      int closed = 0;
+      for (Connection connection : connections) {
+        // stop if connections dropped below threshold unless scanning all
+        if (!scanAll && size() < idleScanThreshold) {
+          break;
+        }
+        // stop if not scanning all and max connections are closed
+        if (connection.isIdle() &&
+            connection.getLastContact() < minLastContact &&
+            close(connection) &&
+            !scanAll && (++closed == maxIdleToClose)) {
+          break;
+        }
+      }
+    }
+
+    void closeAll() {
+      // use a copy of the connections to be absolutely sure the concurrent
+      // iterator doesn't miss a connection
+      for (Connection connection : toArray()) {
+        close(connection);
+      }
+    }
+
+    void startIdleScan() {
+      scheduleIdleScanTask();
+    }
+
+    void stopIdleScan() {
+      idleScanTimer.cancel();
+    }
+
+    private void scheduleIdleScanTask() {
+      if (!running) {
+        return;
+      }
+      TimerTask idleScanTask = new TimerTask(){
+        @Override
+        public void run() {
+          if (!running) {
+            return;
+          }
+          if (LOG.isDebugEnabled()) {
+            LOG.debug(Thread.currentThread().getName()+": task running");
+          }
+          try {
+            closeIdle(false);
+          } finally {
+            // explicitly reschedule so next execution occurs relative
+            // to the end of this scan, not the beginning
+            scheduleIdleScanTask();
+          }
+        }
+      };
+      idleScanTimer.schedule(idleScanTask, idleScanInterval);
+    }
+  }
+
+}
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/hbase/blob/fc93de51/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
----------------------------------------------------------------------
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
index 4c5c935..27fef8d 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
@@ -91,6 +91,7 @@ import org.apache.hadoop.hbase.ipc.RpcCallContext;
 import org.apache.hadoop.hbase.ipc.RpcCallback;
 import org.apache.hadoop.hbase.ipc.RpcServer;
 import org.apache.hadoop.hbase.ipc.RpcServer.BlockingServiceAndInterface;
+import org.apache.hadoop.hbase.ipc.RpcServerFactory;
 import org.apache.hadoop.hbase.ipc.RpcServerInterface;
 import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
 import org.apache.hadoop.hbase.ipc.ServerRpcController;
@@ -1060,7 +1061,7 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
     // Set how many times to retry talking to another server over Connection.
     ConnectionUtils.setServerSideHConnectionRetriesConfig(rs.conf, name, LOG);
     try {
-      rpcServer = new RpcServer(rs, name, getServices(),
+      rpcServer = RpcServerFactory.createRpcServer(rs, name, getServices(),
           bindAddress, // use final bindAddress for this server.
           rs.conf,
           rpcSchedulerFactory.create(rs.conf, this, rs));