SocketChannel-java.net.ConnectException：連接超時：connect

Question

我們的應用程序有時“超時”，我們有一個Java客戶端連接到unix守護程序，由於某種原因，它不時拋出以下錯誤：

SocketException: Cannot establish connection to daemon
java.net.ConnectException: Connection timed out: connect
    at sun.nio.ch.Net.connect(Native Method)
    at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
    at java.nio.channels.SocketChannel.open(Unknown Source)
    at ....
    at java.lang.Thread.run(Unknown Source)

此堆棧跟蹤來自以下代碼：

  try
  {
    InetSocketAddress inetAddress = new InetSocketAddress(InetAddress.getByName(serverName), serverPort);
    socketChannel = SocketChannel.open(inetAddress); // <--- I think the problem is here
    pipeSck = socketChannel.socket();

  }
  catch (NoRouteToHostException e)//when the remote host cannot be reached or connection was refused
  {
    System.err.println("NoRouteToHostException: Cannot establish connection to daemon");
    e.printStackTrace();
    return 1; /* reply only with error */
  }
  catch (SocketException e)//when the remote host cannot be reached or connection was refused
  {
    System.err.println("SocketException: Cannot establish connection to daemon");
    e.printStackTrace();
    return 1; /* reply only with error */
  }

這在99％的時間內都有效...為什么我們會超時？

謝謝！

Answer 1

“連接超時”意味着要么網絡暫時關閉（最有可能），或者如果網絡不在Windows上運行，則服務器的套接字積壓隊列已滿，這可能在極端負載或拒絕運行時發生服務攻擊。

Answer 2

我同意Crollster的觀點，盡管您也可以檢查主機上是否存在防火牆，這可能會引起問題。 UNIX軟管是否有防火牆？ 有中間防火牆嗎？ UNIX主機在本地LAN上嗎？ 如果沒有，您的互聯網訪問不暢嗎？ 聯網很有趣。 :)