> I know it's been a singleton for a while, but with federation, it seems to cause a lot more problems – this test didn't ever time out before. So, I think the singleton issue is a blocker, not just code cleanup, right?
The problem may be more pronounced with federation, but you see that this is a problem for MiniDFSCluster. Are you suggesting this bug needs to be fixed in this jira. I think it is unrelated to what this jira is addressing - that is layout versions changed in
HDFS-1822 causes upgrade issues. Will create a separate jira as I have said earlier.
I think the new jira should be a blocker for 0.23 and not 0.22 (where by lucky coincidence the test works).
> I think the null checks you had to add are also due to this singleton usage – they're masking an issue but don't inherently make sense.
Not sure what you are getting at here. This is an initialization issue that I was addressing. To make progress on this issue, I can revert that part.