Which is faster for IPC sharing of objects -ZeroMQ or Boost::interprocess?

Question

I am contemplating inter-process sharing of custom objects. My current implementation uses ZeroMQ where the objects are packed into a message and sent from process A to process B.

I am wondering whether it would be faster instead to have a concurrent container implemented using boost::interprocess (where process A will insert into the container and process B will retrieve from it). Not sure if this will be faster than having to serialise the object in process A and then de-serialising it in process B.

Just wondering if anyone has done benchmarking? Is it conceptually right to compare the two?

Answer 1

In principle, ZeroMq should be slower, because the metaphor it's using is the passing of messages. These kinds of libraries are not intended for sharing regions of memory, in place, and for different processes to be able to modify them concurrently.

Specifically, you mentioned "packing". When sharing memory regions, you can - ideally - avoid any packing and just work on data as-is (of course, with the care necessary in concurrent use of the same data structures, using offsets instead of pointers etc.)

Also note that even when sharing is a one-directional back-and-forth (i.e. only one process at a time accesses any of the data), ZeroMq can only match the use of IPC shared memory if it supports zero-copying all the way down. This is not clear to me from the FAQ page on zero-copying (but may be the case anyway).