Daniel

Netty

NioEventLoop Thread

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
    ctx.channel().eventLoop().execute(new Runnable() {
        @Override
        public void run() {
            System.out.println("internal " + Thread.currentThread());
        }
    });

    new Thread(()->{
        System.out.println("external 1 " + Thread.currentThread());
        ctx.channel().eventLoop().execute(new Runnable() {
            @Override
            public void run() {
                System.out.println("external 2 " + Thread.currentThread());
            }
        });
    }).start();
    ctx.write(msg);
}

output: external 1 Thread[Thread-0,10,main] internal Thread[nioEventLoopGroup-3-1,10,main] external 2 Thread[nioEventLoopGroup-3-1,10,main]

propagation

ChannelPipeline.addLast(inbound_1); ChannelPipeline.addLast(inbound_2); ChannelPipeline.addLast(inbound_3); ChannelPipeline.addLast(outbound_1); ChannelPipeline.addLast(outbound_2); ChannelPipeline.addLast(outbound_3);

• ChannelHandlerContext.pipeline().fireChannelRead(Object msg); propagate inbound from head util the last inbound handle. inbound_1 -> inbound_2 -> inbound_3
• ChannelHandlerContext.fireChannelRead(Object msg); propagate inbound from current util the last inbound handle. inbound_2 -> inbound_3
• ChannelHandlerContext.channel().write(Object msg); propagate outbound from tail util the last outbound handle. outbound_3 -> outbound_2 -> outbound_1
• ChannelHandlerContext.write(Object msg); propagate outbound from current util the last outbound handle. outbound_2 -> outbound_1
• propagate exception from current inbound util the last inbound and then outbound. inbound_2 -> inbound_3 -> outbound_1 -> outbound_2 -> outbound_3

The best way to handle exception is add a inbound handle at last. ChannelPipeline.addLast(inbound_1); ChannelPipeline.addLast(inbound_2); ChannelPipeline.addLast(inbound_3); ChannelPipeline.addLast(outbound_1); ChannelPipeline.addLast(outbound_2); ChannelPipeline.addLast(outbound_3); ChannelPipeline.addLast(exception inbound);

ByteBuf

• ByteBuf: pool and unpool; safe and unsafe; heap and direct.
• ResourceLeakDetector: PooledByteBufAllocator.newHeapBuffer、PooledByteBufAllocator.newDirectBuffer、UnpooledByteBufAllocator、newDirectBuffer