一台 Jenkins 1.651 master 和 slave 已经安装在 Windows Server 2012 上。 slave 专用于运行 Selenium 测试，但大部分时间它会离线：
Build step 'Execute Windows batch command' marked build as failure
ERROR: slave-tester is offline; cannot locate jdk7
和
Apr 20, 2016 2:20:05 PM INFO jenkins.slaves.DefaultJnlpSlaveReceiver handle
Disconnecting slave-tester as we are reconnected from the current peer
Apr 20, 2016 2:20:17 PM WARNING org.jenkinsci.remoting.nio.NioChannelHub run
Communication problem
java.io.IOException: An existing connection was forcibly closed by the remote host
at sun.nio.ch.SocketDispatcher.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(Unknown Source)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(Unknown …