Ignis: scaling distribution-oblivious systems with light-touch distribution.

Distributed systems offer notable benefits over their centralized counterparts. Reaping these benefits, however, requires burdensome developer effort to identify and rewrite bottlenecked components. Light-touch distribution is a new approach that converts a legacy system into a distributed one using automated transformations. Transformations operate at the boundaries of bottlenecked modules and are parametrizable by light distribution recipes that guide the intended semantics of the resulting distribution. Transformations and recipes operate at runtime, adapting to load by scaling out only saturated components. Our Ignis prototype shows substantial speedups, attractive elasticity characteristics, and memory gains over full replication, achieved by small and backward-compatible code changes.