Currently, the two-phase locking logic only affects mode X and IX locks, and only for database, collection, and metadata Resources.

Mode S and IS locks for any Resource, and Mode X and IX locks for global, mmapv1_flush, and mutex Resources do not participate in two-phase locking; such locks are released as soon as their holder destructs and are not held until the end of a containing WriteUnitOfWork.

This logic should be changed such that the Global resource participates in two-phase locking. Otherwise, it is possible to write code that has a Database resource locked but without an appropriate Global resource lock – a violation of locking rules.