Try thin without threadsafe
Still get rid of Rack::Lock
Revert "Still get rid of Rack::Lock"

This reverts commit 5144ba575b3a9295e6deebcef58620219e3fd46c.
Revert "Try thin without threadsafe"

This reverts commit 9441bfa6d3eb17482228b89c478a3a93e8f7e21d.