Thank you for your reply, I agree there should be a memory barrier for the channel, for it is different from the other assignment statements and not a write operation. Have you got some readings talk about this?
On Tuesday, January 7, 2020 at 10:17:43 AM UTC+8, Kurtis Rader wrote: > > On Mon, Jan 6, 2020 at 5:47 PM hao dong <hao....@gmail.com <javascript:>> > wrote: > >> thanks for your reply. Could you guide me any readings or source code >> about channel of happens before. >> > > I think you have misunderstood this text in the https://golang.org/ref/mem > document you linked to: > > Within a single goroutine, reads and writes must behave as if they >> executed in the order specified by the program. That is, compilers and >> processors may reorder the reads and writes executed within a single >> goroutine only when the reordering does not change the behavior within that >> goroutine as defined by the language specification. Because of this >> reordering, the execution order observed by one goroutine may differ from >> the order perceived by another. > > > The send on the channel is not a "write" operation in the sense meant by > the above text. Nor is the receive on the channel a "read" operation. That > paragraph is talking about reads and writes of memory in units (bytes, > words, etc.) supported by the CPU. Also, notice the "only when the > reordering does not change the behavior" portion of the above text. If the > compiler did the assignment after the send on the channel that would change > the behavior of the program. Channel ops are what are known as memory > barriers, and thus don't allow ops before or after the channel op to be > reordered before or after the op. > > -- > Kurtis Rader > Caretaker of the exceptional canines Junior and Hank > -- 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/37c57f74-f736-4b12-bbb4-ddbac172ec74%40googlegroups.com.
