Dubbo性能参数调优及原理

常用性能调优参数

参数名   作用范围   默认值   说明   备注  
threads   provider   200   业务处理线程池大小      
iothreads   provider   CPU+1   io线程池大小      
queues   provider   0  

线程池队列大小，当线程池满时，排队等待执行的队列大小，

建议不要设置，当线程程池时应立即失败，

重试其它服务提供机器，而不是排队，除非有特殊需求

     
connections   consumer   0  

对每个提供者的最大连接数，

rmi、http、hessian等短连接协议表示限制连接数，

Dubbo等长连接协表示建立的长连接个数

  Dubbo协议默认共享一个长连接  
actives   consumer   0   每服务消费者每服务每方法最大并发调用数   0表示不限制  
acceptes   provider   0   服务提供方最大可接受连接数   0表示不限制  
executes   provider   0   服务提供者每服务每方法最大可并行执行请求数   0表示不限制  

源码及原理分析

>>  threads

FixedThreadPool.Java

public Executor getExecutor(URL url) {
    String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
    int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
    int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
    return new ThreadPoolExecutor(threads, threads, 0, TimeUnit.MILLISECONDS,
            queues == 0 ? new SynchronousQueue<Runnable>() :
                    (queues < 0 ? new LinkedBlockingQueue<Runnable>() :
                            new LinkedBlockingQueue<Runnable>(queues)),
            new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
}

LimitedThreadPool.java

public Executor getExecutor(URL url) {
    String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
    int cores = url.getParameter(Constants.CORE_THREADS_KEY, Constants.DEFAULT_CORE_THREADS);
    int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
    int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
    return new ThreadPoolExecutor(cores, threads, Long.MAX_VALUE, TimeUnit.MILLISECONDS,
            queues == 0 ? new SynchronousQueue<Runnable>() :
                    (queues < 0 ? new LinkedBlockingQueue<Runnable>() :
                            new LinkedBlockingQueue<Runnable>(queues)),
            new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
}

其中，Constants.DEFAULT_QUEUES = 200。threads 参数配置的是业务处理线程池的最大（或核心）线程数。

>>  iothreads

NettyServer.java

@Override
protected void doOpen() throws Throwable {
    NettyHelper.setNettyLoggerFactory();
    ExecutorService boss = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerBoss", true));
    ExecutorService worker = Executors.newCachedThreadPool(new NamedThreadFactory("NettyServerWorker", true));
    ChannelFactory channelFactory = new NioServerSocketChannelFactory(boss, worker, getUrl().getPositiveParameter(Constants.IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS));
    bootstrap = new ServerBootstrap(channelFactory);
       
    final NettyHandler nettyHandler = new NettyHandler(getUrl(), this);
    channels = nettyHandler.getChannels();
    bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
        public ChannelPipeline getPipeline() {
            NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec() ,getUrl(), NettyServer.this);
            ChannelPipeline pipeline = Channels.pipeline();
            pipeline.addLast("decoder", adapter.getDecoder());
            pipeline.addLast("encoder", adapter.getEncoder());
            pipeline.addLast("handler", nettyHandler);
            return pipeline;
        }
    });
    // bind
    channel = bootstrap.bind(getBindAddress());
}

>>  queues