Java SocketChannel 读取时写入被阻止

Question

我尝试在两个不同的线程(Android API 级别 25)中同时使用 SocketChannel.write 和 SocketChannel.read。

我将 SocketChannel 配置为阻塞模式。

为了阅读，我创建了一个无限循环来从服务器读取所有内容:

// Make socketChannel.read() return after 500ms at most
socketChannel.socket().setSoTimeout(500);
while(!SHUTDOWN) {
    int read = socketChannel.read(buffer);
    if(read > 0 ){
      // Do something nice
      break;
    }
}

对于写入，我每 10 秒写入一次数据。

问题是，我发现有时写入操作在读取时会被阻塞。

但是如果我让读取线程在每个循环中 hibernate 一小段时间，例如100ms，这个问题就不会再出现了。

看起来读取线程正在阻塞写入线程

据我所知，TCP 连接可以同时提供双向操作。谁能帮忙解释一下吗？

Answer 1

如 TCP Wikipedia - Flow Control 中所述:

TCP uses an end-to-end flow control protocol to avoid having the sender send data too fast for the TCP receiver to receive and process it reliably. Having a mechanism for flow control is essential in an environment where machines of diverse network speeds communicate. For example, if a PC sends data to a smartphone that is slowly processing received data, the smartphone must regulate the data flow so as not to be overwhelmed.