In the last section we found ServerSocketChannel generation, Selector registration, bound port startup and so on: How does Netty block ServerSocketChannel startup, and then validate the use of Selector generation in Netty and how does our JDK native worker start working in Netty: NioEventLoopGroup

Example source: github.com/jsbintask22…

NioEventLoopGroup

NioEventLoopGroup

SelectProvider

ThreadPerTaskExecutor

And start

Further down, it instantiates all children and that children is an array of NioEventLoop instances (dropping the executor above);

So now the key thing is, when did this NioEventLoop lose a task to ThreadPerTaskExecutor, so let’s keep tracking it NioEventLoop

We have as many selectors as we have threads in the children array

Let’s go back to the registerAndInit() method that was resolved in the previous section

public boolean inEventLoop(Thread thread) {
    return thread == this.thread;
}
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That is, go down first

eventLoop.execute(new Runnable() {
    @Override
    public void run(a) { register0(promise); }});Copy the code

Finally start a new thread using executor commit (remember ThreadPerTaskExecutor) :

NioEventLoop.run()

processSelectedKeys

processSelectedKey

NioMessageUnsafe.read () 

@Override
protected int doReadMessages(List<Object> buf) throws Exception {
    SocketChannel ch = SocketUtils.accept(javaChannel());

    try {
        if(ch ! =null) {
            buf.add(new NioSocketChannel(this, ch));
            return 1; }}catch (Throwable t) {
        logger.warn("Failed to create a new channel from an accepted socket.", t);

        try {
            ch.close();
        } catch (Throwable t2) {
            logger.warn("Failed to close a socket.", t2); }}return 0;
}
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ServerBootstrapAcceptor’s read method is triggered in the pipeline on SererSocketChannel. The newly accepted SocketChannel is registered with the selector again, and the work child thread starts an infinite loop and performs the above operations:

ch.eventLoop().execute