Github user cakofony commented on the issue:
https://github.com/apache/logging-log4j2/pull/150
The ThreadLocals would be constant sized arrays only used for calls to
getParameters in order to avoid creating a new array.
Though now that I think through that idea it would have the potential for
memory leaks unless the arrays are nulled out.
I think I've convinced myself that this PR is the way to go :-)---
