Netty 4, use of ExecutorService

Question

I would like to reuse an ExecutorService across my application.

Reusing a NioWorkerPool across multiple server and client bootstraps

I tried to reproduce the code posted above with netty 4 but i didn't find a way to do it, i also googled quit a lot but it seems we can't provide ExecutorService to a bootstrap or NioEventLoopGroup object.

For example with netty 3 here is how you can share executorservice :

ExecutorService executor = Executors.newCachedThreadPool();
NioClientBossPool clientBossPool = new NioClientBossPool(executor, clientBossCount);
NioServerBossPool serverBossPool = new NioServerBossPool(executor, serverBossCount);
NioWorkerPool workerPool = new NioWorkerPool(executor, workerCount);

ChannelFactory cscf = new NioClientSocketChannelFactory(clientBossPool, workerPool);
ChannelFactory sscf = new NioServerSocketChannelFactory(serverBossPool, workerPool);
...

ClientBootstrap cb = new ClientBootstrap(cscf);
ServerBootstrap sb = new ServerBootstrap(sscf);

But with netty 4, as far as i know you can't use a executorservice ... You must provide a EventLoop implementation like NioEventLoopGroup, but i really would like to use a generic executorService that i will use across my application. Because i want in one thread-pool to have threads doing different kind of work : computation, networks with netty ...

EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
EventLoopGroup workerGroup = new NioEventLoopGroup()
ServerBootstrap b = new ServerBootstrap(); // (2)
        b.group(bossGroup, workerGroup)
         .channel(NioServerSocketChannel.class) // (3)
         .childHandler(new ChannelInitializer<SocketChannel>() { // (4)
             @Override
             public void initChannel(SocketChannel ch) throws Exception {
                 ch.pipeline().addLast(new DiscardServerHandler());
             }
         })
         .option(ChannelOption.SO_BACKLOG, 128)          // (5)
         .childOption(ChannelOption.SO_KEEPALIVE, true); // (6)

Answer 1

in netty 5, NioEventLoopGroup comes with a constructor which takes a executor as parameter:

EventLoopGroup bossGroup = new NioEventLoopGroup(nThreads, yourExecutor);

but I am not sure if this is the case in netty 4