Re: FileSystem object's close method is not called. hadoop 2.7.2
Historically, there has never been a firm requirement that clients must call FileSystem#close upon finishing usage of an instance. I think the history here is that the close method was not part of the initial API definition, and when it was added, there
were already a lot of existing applications coded that were not calling the close method. A tactical decision was made not to force all of those applications to make code changes, so calling close has been treated as optional. (This all pre-dates my time
on the project though, so I might not have the story completely right.)
I'd prefer a hard requirement that applications must call close, but this is our current situation. If you see a specific point in the codebase where you'd like to propose adding a close call, then I recommend filing an Apache JIRA to discuss the proposal.
If you'd like, also consider attaching a patch to the JIRA.