Interesting, thanks for the explanation! On Thu, Jul 15, 2021 at 12:23 PM Ian Lance Taylor <i...@golang.org> wrote:
> 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/CAL9jXCGWMxwqKSsG%2BHzY4s5-zrvywg%2BTZTqqy11Fjz5GoVVV2w%40mail.gmail.com.
