  Distributed Transactional Memory (DTM) is an emerging approach to distributed
synchronization based on the application of the transaction abstraction to
distributed computation. DTM comes in several system models, but the control
flow model (CF) is particularly powerful, since it allows transactions to
delegate computation to remote nodes as well as access shared data. However,
there are no existing CF DTM systems that perform on par with state-of-the-art
systems operating in other models. Hence, we introduce a CF DTM synchronization
algorithm, OptSVA-CF. It supports fine-grained pessimistic concurrency control,
so it avoids aborts, and thus avoids problems with irrevocable operations.
Furthermore, it uses early release and asynchrony to parallelize concurrent
transactions to a high degree, while retaining strong safety properties. We
implement it as Atomic RMI 2, in effect producing a CF DTM system that, as our
evaluation shows, can outperform a state-of-the-art non-CF DTM such as HyFlow2.
