Yeah, that's an issue with conservative garbage collectors. When memory actually in use is a large fraction of the address space, then random values can look li

Yeah, that's an issue with conservative garbage collectors. When memory actually in use is a large fraction of the address space, then random values can look like pointers too often. When valid_memory << address_space, on the other hand, most non-pointer values won't alias a valid pointer. The specific issue with Go was significantly mitigated in Go 1.1 by making much more of the GC precise rather than conservative. Here's a comment from about a month ago on the current state: http://code.google.com/p/go/issues/detail?id=909#c59 http://code.google.com/p/go/issues/detail?id=909#c59