Hi all, as I’m digging into IoTDB more and more, I noticed a quite excessive usage of the Singleton pattern … some times even for things where it doesn’t really make much sense. For example in SystemFileFactory, the methods don’t really have much state and simply fire RuntimeExceptions if fsType is initialized with HDFS.
Singletons make it a bit tricky to run tests in parallel and to do dynamic reloading of modules (like in OSGI). Most projects I’ve worked on try to limit the use of singletons to an absolute minimum due to these problems. I guess embedding IoTDB in an OSGI environment hasn’t been a use-case yet, but I could imagine that random test failures while running tests in parallel probably could have caused some issues. Was this a design decision that is based on some real-world necessity, or for simplifying things during development? I don’t want to put too much effort into proposing cleaning up things, if there was a conscious decision to do things otherwise. Chris
