Potential GC problem through use of gensym to generate blank nodes

[RickMoynihan]

When we generate blank nodes for various annotation data, we make use of clojure's gensym to generate unique names (within the processes execution).

gensym interns strings which for large inputs will cause at least one bnode per row. Interning these will make these strings less eligible for garbage collection, likely resulting in larger GC pauses etc.

There may be arguments for interning more commonly used URIs such as predicates and classes, to help reduce memory foot print but blank nodes will if anything have the opposite effect.

See also posts such as this: https://shipilev.net/jvm/anatomy-quarks/10-string-intern/