Reproducing the AWS Outage Race Condition with a Model Checker

As mentioned previously, I think the only tools that are really valuable should be able to produce code, naturally with multiple possible languages as backends, that are then used as library from the application code.

Something like Lean, F*, Dafny, even if that isn't exactly the same as TLA+.

QA people deal with problems and edge cases most devs will never deal with. They’re your subject-matter-experts of 'what can go wrong'.

Anyway, the point is. You can’t trust anything "will resolve in time period X" or "if it takes longer than X, timeout". There are so many cases where this is simply not true and should be added to a "myths programmers believe" article if it isn't already there.

Here we see the basic steps of modeling a complex system, and how that can be useful for understanding behavior even without knowing the details of every component.

Agree, but Time-of-Check to Time-of-Use is a pretty well established failure mode.

While one can and will add invariants, as they are discovered, they cannot all be found.

Entscheidungsproblem and Trakhtenbrot's theorem apply here, counterintuitively that the validity of finite models is in co-re but not in re.

Validity in this case is not dependent by the truth of the premise or the truth of the conclusion.

Basically we have to use tools like systems thinking to construct robust systems, we cannot universally use formal methods across frames.

It is one way race conditions are complex.

Hindsight bias makes it seem easy but that is because that is in the co-re side.

Well intended actions with hindsight can often result in brittle systems as their composition tends to set systems in stone, with the belief that axioms are the end solution.

The fact that Gödels completeness theorem may not apply for finite systems when it works so well for infinite ones is hard for me to remember.

Remembering that axiomatization is a powerful tool but not a silver bullet has actually helped me more than I can count.

[0] http://jmc.stanford.edu/articles/circumscription/circumscrip...

If you added model checking to it you could have prevented it though, because people that know how to program a model checking program, will see the error right away.