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Fat pointers + threads permit torn reads/writes, leading to memory unsafety. It seems weird that Go allowed memory unsafety for this narrow use case - AFAIK only slices and interfaces are fat pointers.



There's some discussion about unsafety in the face of concurrency from Rob Pike here: https://talks.golang.org/2012/splash.article#TOC_13.

> There is one important caveat: Go is not purely memory safe in the presence of concurrency. Sharing is legal and passing a pointer over a channel is idiomatic (and efficient).

> Some concurrency and functional programming experts are disappointed that Go does not take a write-once approach to value semantics in the context of concurrent computation, that Go is not more like Erlang for example. Again, the reason is largely about familiarity and suitability for the problem domain. Go's concurrent features work well in a context familiar to most programmers. Go enables simple, safe concurrent programming but does not forbid bad programming. We compensate by convention, training programmers to think about message passing as a version of ownership control. The motto is, "Don't communicate by sharing memory, share memory by communicating."


If you need thread-safety you must at least use atomics anyway Either your platform has transactional memory, double-wide cas or you need to fall back to locks.


Using double wide cas for atomic pointer store and loads is a big pessimization though.


I was of the impression that even regular pointers could allow for memory unsafety but I can’t recall exactly what I had heard that gave me that impression...




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