Is there any recommended lightweight pubsub service/library?

I'm building a small system that contains many parts and I want to use a message pub/sub service to communicate between parts.

I read about some message queue services like RabbitMQ and ZeroMQ but I feel they are too complicated and feel like it was born for distributed system. All parts of my system will be written in C++/Linux and place on a small Raspberry Pi CPU, so I dont need feature like scalable, cross-platform, other language clients ...

Can you guys give me some advice about services or libraries that fit my need?