Comment by ip26
14 hours ago
I mean to ask both: "checking whether X is true and crashing the program if not", like the assert macro, OR assert as in a weaker check that does not crash the program (such as generate a log event).
When crashing the program is acceptable and correctness preconditions can be efficiently checked, postconditions usually can be too.
What's interesting to me is the combination of two claims: formal verification is used when crashes are not acceptable, and crashing when formal assumptions are violated is therefore not acceptable. This makes sense on the surface - but the program is only proven crashproof when the formal assumptions hold. That is all formal verification proves.
It's more that adding intentional conditional crashes to the program in situations where crashing is the worst possible outcome can't possibly make the situation better. It might not make it worse, if the crashes never happen.
As for log messages, yeah, people do commonly put log messages in their software for when things like internal consistency checks fail.
I believe this is a false dichotomy. It's interesting but it also demands no third way exist.
For example I have run services which existed inside a forever() loop. They exit, and are forceably restarted. Is that viable for a flight control system? No. Does it allow me to meet a low bounds availability problem with OOM killers? Yes, until the size of a quiescent from-boot system causes OOM.
BGP speakers who compile in runtime caps on the prefix count can be entirely stable and run BGP "correctly" right up to the point somebody sends them more than the cap in prefixes. That can take hours to emerge. I lived in that world for a while too.