ContainerShellWebSocket gives inaccurate log message saying "... closed!" before trying to close the session

Hello,

While viewing the MAPREDUCE-4262, it seems that the logging statements might give inaccurate messages. 

I also found another same issue: the in the line 143 of the file ContainerShellWebSocket, the log messages says "...  closed!". However, there are other closing actions (source code) after the logging statement, which means that the close is still not completed.

Would it be better if we change the verb "closed" to "closing" to indicate the action is in progress? Or can we move the logging statement to the end of the method? 

Related issue: https://issues.apache.org/jira/projects/YARN/issues/YARN-11143