Can this actually manifest? Even without the -race flag I think maps are a special case which will panic with a concurrent mutation error if access isn't synchronized.
> In the current Go implementations, though, there are two ways to break through these safety mechanisms. The first and more direct way is to use package unsafe, specifically unsafe.Pointer. The second, less direct way is to use a data race in a multithreaded program.
It's interesting that the 2010 article you linked suggests they might consider improving this but nope, Go 1.0 and the Go people use today just basically takes the same attitude as C and C++ albeit with a small nuance.
In C and C++ SC/DRF (Sequentially Consistent if Data Race Free) turns into "All data races are Undefined Behaviour, game over, you lose". In Go SC/DRF turns into "All data races on complex types are Undefined Behaviour, game over, you lose". If you race e.g. a simple integer counter, it's damaged and you ought not to use it because it might be anything now, but Go isn't reduced to Undefined Behaviour immediately for this seemingly trivial mishap (whereas C and C++ are)
Go doesn't go out of its way to make weird things happen on UB like C compilers these days tend to, but once you corrupt the map data structure, weird things can happen. Trying to contain that explosion isn't necessarily "better", as it would make maps slower / take up more memory / etc.
> Go doesn't go out of its way to make weird things happen on UB like C compilers these days tend to
The reasons C compilers “tend to go out of their way to make weird things happen” is they optimise extremely aggressively, and optimisations are predicated upon the code being valid (not having UBs).
Go barely optimises at all, and does not have that many UBs which could send the optimiser in a frenzy.
Kind of ironic the raison d'être of Go is a memory safe language for concurrent programming but you can easily footgun yourself into doing something memory unsafe using concurrency...
Implicitly shared memory is literally the default behaviour of the langage, and you have to be careful to keep that controlled or contained.
Pretty much as in every other shared memory concurrency langage.
The quip about sharing memory by communicating is cute but it’s just that, the langage does not encourage let alone enforce it.
In fact it went out of its way to remove some opportunities e.g. because `go` is a statement there is no handle which could communicate the termination and result of routines.
Another example: thread A toggles an interface variable between two types, thread B calls a method on it. You can get the method of type X called with a receiver of type Y.
There are ways a Go program can fatal: by running out of heap, or stack, by corrupting variables by racing writes, by deadlocking, by misuse of reflect or unsafe, and so on.
I’ve seen it happen before because the stdlib actually directly just makes POSIX syscalls for a lot of things by default instead of using the native Go implementations and so you’re implicitly reliant on C code
