“Stack confinement is a special case of thread confinement in which an object can only be reached through local variables. Just as encapsulation can make it easier to preserve invariants, local variables can make it easier to confine objects to a thread. Local variables are intrinsically confined to the executing thread; they exist on the executing thread's stack, which is not accessible to other threads. Stack confinement (also called within-thread or thread-local usage, but not to be confused with the ThreadLocal library class) is simpler to maintain and less fragile than ad-hoc thread confinement. For”