Here are my thoughts on the free online textbook Is Parallel Programming Hard, And, If So, What Can You Do About It? by Paul E. McKenney, author of the Linux kernel’s RCU synchronization mechanism . I read a lot of this textbook, got my fill, and probably won’t read more of it in the near future so wanted to write this review while it is all still fresh. Set & Setting Here I’ll talk about the mindset/life phase and physical setting I was in when I started reading this textbook. This might be like the tedious personal flavor preamble they have on recipe websites so skip ahead if that does not interest you. My professional life had revolved around TLA⁺ & distributed systems for the past decade, and I was thinking it was time for a change. A transitional and emotionally tumultuous period! In 2022 I had tried (and failed) to move to Lean, hoping to acquire an unbelievably niche & nonexistent job as the guy who formalizes researchers’ quantum information processing results for them.…