Figuring out how a bug happens can easily take 20 minutes of concentration. "This thread calls this method, that one sends this message, then a request arrives

Figuring out how a bug happens can easily take 20 minutes of concentration. "This thread calls this method, that one sends this message, then a request arrives here while this lock is held...". It's in tracking down tricky bugs that I find focus is most needed: if I'm in an easily-distracted state then I will basically spend hours getting nowhere.