The only guarantees made in regards to alignment are the ones outlined here: https://golang.org/ref/spec#Size_and_alignment_guarantees >From what I can tell, there is no such guarantee. But why do you care, specifically? Using the sync/atomic package will handle this correctly in every case. This reeks of an XY-problem <http://xyproblem.info/> - what is the *actual problem* you are trying to solve? There likely is a better way to handle your problem (e.g. you say that there is only a single write, so sync.Once <https://godoc.org/sync#Once> might help? Or sync.Cond <https://godoc.org/sync#Cond>?). When I said your program will be incorrect, I wasn't being cautious, I was being literal.
On Mon, Jan 9, 2017 at 3:03 PM, 陈诚 <ncu.br...@gmail.com> wrote: > Thanks for your caution. Then is there a way to know that a certain > variable is aligned properly? Will the compiler make the global variable > `var p *int` in my sample code aligned properly? > > 在 2017年1月9日星期一 UTC+8上午3:17:37，Dave Cheney写道： > >> What you are talking about is called a torn write, which can occur if a >> value is written to memory but not aligned properly as the processor or >> memory subsystem must convert this write into two to correct for the miss >> alignment. >> >> Most processors that I know of, and all the ones that Go supports, >> assuming that the value is correctly alligned will write the value >> atomically, IE another processor will not see a partially written value. >> >> However, I must caution you that while you say it is ok for one processor >> to see an old value for a time, this is not how the Go memory model works. >> There are no concessions for "for a time" and so on, the updated value may >> never be written to memory, or the old value may continue to be visible for >> the remainder of the program's run time. >> >> The memory model describes what you ask for as a data race and states >> that your program is no longer guaranteed to run correctly. Or put more >> suscinctly, if you have a data race, the result of your program is >> undefined. >> >> -- > 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. > -- 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.
