gistfile1.java

java.nio.channels.FileChannel myFile = ...;
java.nio.channels.SocketChannel mySocket = java.nio.channels.SocketChannel.open();

// Perform some blocking operation here.
...

// Netty takes over.
SocketChannel ch = new NioSocketChannel(mySocket);
EventLoopGroup group = ...;
group.register(ch);
...

// Deregister from Netty.
ch.deregister().sync();

// Perform some blocking operation here.
mySocket.configureBlocking(false);
myFile.transferFrom(mySocket, ...);

// Register back again to another event loop group.
EventLoopGroup anotherGroup = ...;
anotherGroup.register(ch);