HashStore Class Variables Causing Conflicts Upon Import

In FileHashStore, thread and multiprocessing variables (threading.Lock(), multiprocessing.Lock(), etc.) are declared outside of the __init__ process. This can create conflicts upon importing hashstore as a library, and not part of a main method in a python program (which can guard against top-level code being executed in new processes unintentionally).

This is especially true with the multiprocessing module due to the nature of how processes are spawned and initialized. Each new spawn process will re-import the module (recursive import).

Example RunTime Error (that was also experienced by Jeanette on MacOS)

These should not be declared as class variables, but determined upon instantiation instead so that it does not interfere with the initial set-up phase of the Python interpreter and its environment (ex. move them to the __init__ method).

DataONEorg / hashstore

HashStore Class Variables Causing Conflicts Upon Import #119