The books went into detail and since reading them I've felt confident writing scripts I needed to scratch an itch. Over time, I grew comfortable believing I had a strong grasp of the practical details and anything I hadn't seen was likely either minor quibble, domain specific, or impractically theoretic.
This was until last year when I started working on a trading bot. I felt there should be two distinct parts to the bot, one script getting data then passing that data along to the other script for action. This seemed correct as later I might want multiple scripts serving both roles and passing data all around. Realizing the scripts would need to communicate over a network with minimal latency, I considered named pipes, Unix domain sockets, even writing files to /dev/shm but none of these solutions really fit.
Googling, I encountered something I hadn't heard of called a message queue. More specifically, the ZMQ messaging library. Seeing some examples I realized this was important. The step of then plowing through the docs was nothing short of revelatory. Every next chapter introduced another brilliant pattern. While grokking Pub/Sub, Req/Res, Push/Pull and the rest I couldn't help breaking away, staring in space, struck by how this new thing I had just read could have deftly solved some fiendish memorable problem I'd previously struggled against.
Later, I pondered the meaning of only now stumbling on something so powerful, so fundamental, so hidden in plain sight, as messaging middleware? What other great tools remain invisible to me for lack of even knowing what to look for?
My question: In the spirit of generally yet ridiculously useful things like messaging middleware, what non-obvious tools and classes of tools would you suggest a hobbyist investigate that they otherwise may never encounter?