On Wed, Jun 7, 2023 at 7:05 AM Ian Lance Taylor <i...@golang.org> wrote: > > On Tue, Jun 6, 2023 at 4:31 PM Caleb Spare <cesp...@gmail.com> wrote: > > > > Can someone explain why the following test shows a race between the > > indicated lines? > > > > https://github.com/cespare/misc/blob/b2e201dfbe36504c88e521e02bc5d8fbb04a4532/httprace/httprace_test.go#L12-L43 > > > > The race seems to be triggered by the very last line of the test: > > > > get(client1) > > > > If I comment that out, then the race detector doesn't complain. But > > then it seems that a read of a variable which happens before an HTTP > > request which causes a write of the variable ultimately races with the > > original read, which doesn't make sense. > > > > It seems like a false positive (perhaps the race detector doesn't > > understand causality across a TCP connection?), but so far I've never > > seen the race detector have a false positive, so I think I must be > > missing something. > > > > I wrote a slightly simpler test (see TestHTTPRace2 right below in the > > same file) which tries to make the race happen using a regular HTTP > > handler and a single client and the race detector doesn't complain. > > I haven't looked at your case in full detail. But it's true that the > race detector does not know anything about TCP connections. In > general it only knows about the cases described in the Go memory model > (https://go.dev/ref/mem). It does seem that your code is only > avoiding a race because the TCP read serializes the server goroutine > and the main client goroutine. The race detector doesn't know > anything about that.
Makes sense, but then I don't understand why the second test doesn't show a race as well. Caleb -- 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/CAGeFq%2Bk_p%3D4rfHT0v%3Dxz7cSaWqqhUem423enOD-_s6Ub8Wwpvg%40mail.gmail.com.
