Merge branch 'master' into SocketChannelStream

Author: jglick

src/main/java/org/jenkinsci/remoting/engine/JnlpProtocol4Handler.java

@@ -193,6 +193,7 @@ public Future<Channel> connect(@NonNull Socket socket, @NonNull Map<String, Stri
     private NetworkLayer createNetworkLayer(Socket socket) throws IOException {
         NetworkLayer networkLayer;
         SocketChannel socketChannel = isPreferNio() ? socket.getChannel() : null;
+        LOGGER.fine(() -> "prefer NIO? " + isPreferNio() + " actually using NIO? " + (socketChannel != null));
         if (socketChannel == null) {
             networkLayer = new BIONetworkLayer(ioHub, Channels.newChannel(SocketChannelStream.in(socket)),
                     Channels.newChannel(SocketChannelStream.out(socket)));

src/main/java/org/jenkinsci/remoting/protocol/impl/AckFilterLayer.java

@@ -173,6 +173,7 @@ private boolean receivedPartialAck() {
     public void start() throws IOException {
         synchronized (sendLock) {
             timeout = stack().executeLater(() -> {
+                LOGGER.info("Timeout waiting for ACK");
                 IOException cause = new IOException("Timeout waiting for ACK");
                 abort(cause);
                 try {