  Despite the stringent requirements of a real-time system, the reliance of the
Robot Operating System (ROS) on the loopback network interface imposes a
considerable overhead on the transport of high bandwidth data, while the
nodelet package, which is an efficient mechanism for intra-process
communication, does not address the problem of efficient local inter-process
communication (IPC). To remedy this, we propose a novel integration into ROS of
smart pointers and synchronisation primitives stored in shared memory. These
obey the same semantics and, more importantly, exhibit the same performance as
their C++ standard library counterparts, making them preferable to other local
IPC mechanisms. We present a series of benchmarks for our mechanism - which we
call LOT (Low Overhead Transport) - and use them to assess its performance on
realistic data loads based on Five's Autonomous Vehicle (AV) system, and extend
our analysis to the case where multiple ROS nodes are running in Docker
containers. We find that our mechanism performs up to two orders of magnitude
better than the standard IPC via local loopback. Finally, we apply
industry-standard profiling techniques to explore the hotspots of code running
in both user and kernel space, comparing our implementation against
alternatives.
