> can you explain the changes in FSNamesystem.java?
That change fixes error handling in FSNamesystem. Previously, we did not call FSNamesystem::shutdown() when initialization failed. This led to the MBeans staying registered. This is irrelevant when running the NameNode normally, since the MBeans are destroyed when the entire process goes away. However, when run from a test context, the next attempt to create a MiniDFSCluster instance will fail with "port in use" or some such error.
> Can you update the logging in the test cases to use StringUtils.stringifyException to match trunk?
> Did you run all the existing tests in branch-1?
I ran these tests: