Add lock around Get in session cache, and add default "unknown" username.
Add lock around Get in session cache, and add default "unknown" username.

daviddumas/pgina,pgina/pgina,MutonUfoAI/pgina,pgina/pgina,stefanwerfling/pgina,MutonUfoAI/pgina,stefanwerfling/pgina,stefanwerfling/pgina,daviddumas/pgina,MutonUfoAI/pgina,pgina/pgina,daviddumas/pgina