netty-threadpool

jdk实现线程池是用ThreadPoolExecutor继承AbstractExecutorService，方式是任务放入一个队列，然后开启多个线程

netty没有使用jdk的threadPoolExecutor，而是自己实现，也是通过继承jdk的AbstractExecutorService

jdk抽象类

public abstract class AbstractEventExecutor extends AbstractExecutorService implements EventExecutor

netty继承jdk抽象类

public abstract class AbstractScheduledEventExecutor extends AbstractEventExecutor

单线程线程池

public abstract class SingleThreadEventExecutor extends AbstractScheduledEventExecutor implements OrderedEventExecutor
{
  队列使用 LinkedBlockingQueue
}

多线程线程池

public interface EventExecutorGroup extends ScheduledExecutorService, Iterable<EventExecutor> 

public interface EventLoopGroup extends EventExecutorGroup

public abstract class AbstractEventExecutorGroup implements EventExecutorGroup
{
  next().xxx
}

public abstract class MultithreadEventExecutorGroup extends AbstractEventExecutorGroup
{
  private final EventExecutor[] children;
  实现了next()，以一定策略EventExecutorChooserFactory.EventExecutorChooser，选择children里的EventExecutor
}

public abstract class MultithreadEventLoopGroup extends MultithreadEventExecutorGroup implements EventLoopGroup

NioEventLoopGroup线程池实现方式是，生成多个children，每个child是单线程线程池SingleThreadEventExecutor，所以是一个线程对应一个队列，有多组

public class NioEventLoopGroup extends MultithreadEventLoopGroup {
  
      protected EventLoop newChild(Executor executor, Object... args) throws Exception {
        EventLoopTaskQueueFactory queueFactory = args.length == 4 ? (EventLoopTaskQueueFactory) args[3] : null;
        // NioEventLoop是个单线程线程池SingleThreadEventExecutor
        return new NioEventLoop(this, executor, (SelectorProvider) args[0],
            ((SelectStrategyFactory) args[1]).newSelectStrategy(), (RejectedExecutionHandler) args[2], queueFactory);
    }
}

public final class NioEventLoop extends SingleThreadEventLoop {
  重写newTaskQueue，使用Mpsc.newMpscQueue（org.jctools.queues的多生产者单生成者队列）
}

public abstract class SingleThreadEventLoop extends SingleThreadEventExecutor implements EventLoop