On Sun, Aug 14, 2016 at 9:58 AM, Gaurav Agarwal <gauravagarw...@gmail.com> wrote: > Ian, thanks for the explanation and the link ! > > But I am still unclear how to implement such a concurrent counter in Go - > given that we can't find out what thread/cpu is the goroutine executing. > Note that in this case there was never the need of pinning a goroutine to a > thread or cpu; just that we wanted to know which is it, at any given moment > so as to access the required memory location. > > Do you have any alternate ideas for this?
I think the last time a similar though not identical concept was discussed was this thread: https://groups.google.com/d/msg/golang-nuts/zt_CQssHw4M/TteNG44geaEJ It would be interesting to know what the potential speedup is. It should be easy enough to write a C program to measure that. But when writing such a program, remember that no real program will simply increment a concurrent counter. The question is not just how much speedup you can get from a concurrent counter, but how much it will matter to a real program. Anyhow, that aside, if you know how many goroutines you are going to run, just allocate a slice with that many elements. If you don't, use a set of fixed size arrays and have each goroutine grab a pointer to a possibly-new array when it starts. Pass down the pointer. If these approaches seem awkward, I suppose you could get syscall(syscall.GETCPU, ...) when you want to increment a counter. But that would admittedly introduce overhead that would distort the results. We do not plan to modify the Go runtime to expose a thread or CPU ID, because although it's true that your application doesn't care much if the value becomes immediately stale, other applications would care. It seems unwise to expose a value that is extremely easy to misuse in a way that will often succeed and occasionally and inexplicably fail. 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. For more options, visit https://groups.google.com/d/optout.
