On Wed, Jul 14, 2021 at 2:11 PM ben...@gmail.com <benh...@gmail.com> wrote: > > Out of interest, why was that changed? Was the optimization not worth it? Did > it just require too much special handling so the code was unclear?
When we switched to using a concurrent garbage collector, we had to consider the possibility that the program would change an interface value from a type that used a pointer to a type that used a scalar value exactly as the concurrent collector was examining the interface value. Any simple approach would lead to races where the garbage collector would misunderstand a scalar value as a pointer or vice-versa, leading to dangling pointers or incorrectly retained memory. The simplest way to resolve the issue was to change interfaces to always use pointers. Ian > On Wednesday, July 14, 2021 at 8:32:06 AM UTC+12 Ian Lance Taylor wrote: >> >> On Tue, Jul 13, 2021 at 1:29 PM Kristoffer Semelka <ksem...@gmail.com> wrote: >> > >> > I noticed that word sized datatypes can be stored directly in the data >> > field of an iface/eface, but I'm confused on how marking works with these >> > kinds of inline cases. I checked the mark routines in the >> > runtime/gcmark.go and couldn't find special casing for interfaces. How >> > does the runtime know when not to follow an interface's data pointer? Does >> > it just scan that word conservatively? How does the func's pointer map fit >> > into this? >> >> In the current implementations the data field of an interface value is >> always a pointer. It was once true that small scalar values were >> stored directly in interface values, but that is no longer true today. >> >> Ian > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/0e940dea-7e1a-41a4-ad8f-4784a943be98n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcXr5MgyXY-_C5JZBotKDLAyGNodbpo_YjwfR1T%3DMq5zBw%40mail.gmail.com.
