Totally agree. I also have written a lot of multithreaded code in the past years. At the beginning I really used locks and acted on various resources from multi

Totally agree. I also have written a lot of multithreaded code in the past years. At the beginning I really used locks and acted on various resources from multiple threads. It turned out to get into an unmaintainable mess where you have to think about dozens of invariants before each change. In the meantime I mostly implement things in a way that each data is owned by exactly on thread (or mostly event loops running on a thread or also in a thread pool) and provide thread-safe APIs on top of that by using queues and message (or function object) passing to exchange data and results between the calling thread and the resource-owning thread.