慢速网络性能

Question

我正在使用netty从服务器下载大型文件。在使用starts运行性能测试时，我发现我的服务器提供了非常高的吞吐量，直到150个并发用户，但是当并发用户数量增加时，它就开始下降，在500个并发用户上几乎减半。

NettyServer -

ServerBootstrap b = new ServerBootstrap();
    EpollEventLoopGroup bossGroup = new EpollEventLoopGroup();
    EpollEventLoopGroup workerGroup = new EpollEventLoopGroup();
  try {
        b.group(bossGroup, workerGroup).channel(EpollServerSocketChannel.class).handler(new LoggingHandler(LogLevel.DEBUG)).childHandler(new FileServerInitializer());
        Channel ch = b.bind(port).sync().channel();
        ch.closeFuture().sync();

    } finally {
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
        FileServerHandler.threadPool.shutdownNow();
    }

FileServerInitializer -

ChannelPipeline pipeline = ch.pipeline();
    pipeline.addLast("decoder", new HttpRequestDecoder());
    pipeline.addLast("aggregator", new HttpObjectAggregator(65536));
    pipeline.addLast("encoder", new HttpResponseEncoder());
    pipeline.addLast("chunkedWriter", new ChunkedWriteHandler());
    pipeline.addLast("handler", (ChannelHandler) new FileServerHandler());
}

FileServerHandler -

    RandomAccessFile raf;
    try {
        raf = new RandomAccessFile(file, "r");
    } catch (FileNotFoundException ignore) {
        sendError(ctx, HttpResponseStatus.NOT_FOUND);
        return;
    }
    response = new DefaultHttpResponse(HTTP_1_1, HttpResponseStatus.OK);
    response.headers().set(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + fileNameType);
    response.headers().set(HttpHeaders.CONTENT_LENGTH, String.valueOf(size));

    ctx.write(response);
    ChannelFuture sendFileFuture;
    ChannelFuture lastContentFuture;
    sendFileFuture = ctx.writeAndFlush(new HttpChunkedInput(new ChunkedFile(raf, 0, size, 8192)),ctx.newProgressivePromise());
    lastContentFuture = sendFileFuture; 
    sendFileFuture.addListener(new ChannelProgressiveFutureListener() {

        public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {
            if (total < 0) {            
                System.out.println(future.channel() + " Transfer progress: " + progress);
            }else {
                System.out.println(future.channel() + " Transfer progress: " + progress + " / " + total);
            }
        }

        public void operationComplete(ChannelProgressiveFuture future) {
            System.out.println(future.channel() + " Transfer complete.");
        }
    });

    lastContentFuture.addListener(ChannelFutureListener.CLOSE);

有人能告诉我为什么会这样吗？

Answer 1

你也可以试着：

1. 例如，在网络端更改子属性(获取自己的正确值) bootstrap.channel(NioServerSocketChannel.class)；bootstrap.group(groupBoss，groupWorker)；bootstrap.option(ChannelOption.TCP_NODELAY，true)；bootstrap.option(ChannelOption.SO_REUSEADDR，真)；bootstrap.option(ChannelOption.SO_LINGER，0)；bootstrap.childOption(ChannelOption.SO_REUSEADDR，true；bootstrap.childOption(ChannelOption.SO_REUSEADDR，true)；bootstrap.childOption(ChannelOption.SO_KEEPALIVE，true)；bootstrap.childOption(ChannelOption.SO_LINGER，0；bootstrap.childOption(ChannelOption.CONNECT_TIMEOUT_MILLIS，超时)；bootstrap.childOption(ChannelOption.SO_RCVBUF，1048576；bootstrap.childOption(ChannelOption.SO_SNDBUF，1048576)；bootstrap.childOption(ChannelOption.WRITE_BUFFER_HIGH_WATER_MARK，10*65536；bootstrap.childOption(ChannelOption.WRITE_BUFFER_LOW_WATER_MARK，2*65536；bootstrap.childOption(ChannelOption.ALLOCATOR，PooledByteBufAllocator.DEFAULT)；
2. 调整BOSS和WORKER端的线程数量(默认为2N+1，其中N是Boss的核心编号，如果我回忆正确的话) 我通常为Boss设置2N+1，为worker设置10N+1 (将Worker视为异步工作人员，这意味着这并不是对并发客户端的真正限制，而是对“真实的”并发客户端的限制，这意味着它们实际上做了一些事情)。在Linux上要小心，相应地增加文件描述符的限制。
3. 更精确地指定工作线程级别。

当然也会看到其他的建议