zookeeper出现CancelledKeyException异常信息

zookeeper集群出现异常信息如下：

ERROR [CommitProcessor:0:NIOServerCnxn@445] - Unexpected Exception:
java.nio.channels.CancelledKeyException
at sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:73)
at sun.nio.ch.SelectionKeyImpl.interestOps(SelectionKeyImpl.java:77)
at
org.apache.zookeeper.server.NIOServerCnxn.sendBuffer(NIOServerCnxn.java:418)
at
org.apache.zookeeper.server.NIOServerCnxn.sendResponse(NIOServerCnxn.java:1509)
at
org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:171)
at
org.apache.zookeeper.server.quorum.CommitProcessor.run(CommitProcessor.java:73)

这个异常的根本原因是什么造成的？？？