OPC客户端代码中出现以下错误。我启动我的客户端-关闭它-再次启动它，看到以下错误。很明显，是上一次运行中的某些原因导致了它。但我无法弄清楚是什么。
当我第一次跑的jstack出现差异并结束时。我没有看到任何来自opc的正在运行的线程。
有人看过这个问题吗？或有没有其他方法可以调试这个问题？
2016-05-19 16:35:53,564 WARN [netty-event-loop-0] io.netty.channel.ChannelInitializer - Failed to initialize a channel. Closing: [id: 0xe25cac5b] java.lang.ExceptionInInitializerError
at com.digitalpetri.opcua.stack.client.UaTcpStackClient$1.initChannel(UaTcpStackClient.java:340)
at com.digitalpetri.opcua.stack.client.UaTcpStackClient$1.initChannel(UaTcpStackClient.java:337)
at io.netty.channel.ChannelInitializer.channelRegistered(ChannelInitializer.java:69)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRegistered(AbstractChannelHandlerContext.java:133)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRegistered(AbstractChannelHandlerContext.java:119)
at io.netty.channel.DefaultChannelPipeline.fireChannelRegistered(DefaultChannelPipeline.java:733)
at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:449)
at io.netty.channel.AbstractChannel$AbstractUnsafe.access$100(AbstractChannel.java:377)
at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:423)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:380)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:357)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116)
at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.IllegalArgumentException: 'awaiting-handshake' is already in use
at io.netty.util.UniqueName.<init>(UniqueName.java:53)
at io.netty.util.AttributeKey.<init>(AttributeKey.java:47)
at io.netty.util.AttributeKey.valueOf(AttributeKey.java:39)
at com.digitalpetri.opcua.stack.client.handlers.UaTcpClientAcknowledgeHandler.<clinit>(UaTcpClientAcknowledgeHandler.java:44)
... 13 more
看起来您可能有某种ClassLoader问题-UaTcpAcknowledgeHandler的静态最终字段不知怎么被定义了两次。
当你"关闭"你的客户时，会发生什么？