On Wed, Feb 26, 2020 at 8:36 PM Robert Engels <reng...@ix.netcom.com> wrote: > > The problem is that Go designers are taking the position that any sys call > should be able to be interrupted. This is invalid. For the vast majority or > “unix” os an interrupt is a very rare condition and so they treat it as an > error. If you issue interrupts continually you are creating an unexpected > context.
You're right, I do disagree. I don't think it's the Go developers who are taking that position. It's the Unix library developers. While a main program can make its own choices about signals, a library has to consider the possibility that it will be included in a program that uses signals. A rare error is still an error. Just because Go 1.14 interrupts system calls more often doesn't mean the system calls were not interrupted. And non-Go programs use signals too, e.g. SIGURG and SIGIO. Ian > > On Feb 26, 2020, at 8:39 PM, Ian Lance Taylor <i...@golang.org> wrote: > > > > On Wed, Feb 26, 2020 at 5:51 PM Michael Jones <michael.jo...@gmail.com> > > wrote: > >> > >> Sorry...I meant the go system signal interface could loop if desired. (Not > >> recommending, just saying that panicky people could be coddled if desired) > > > > Ah, I see. Except, no, I don't. Could we really do that? Even if > > the signal arrived while executing some function written in C and > > called via cgo? > > > > Ian > > > > > >>> On Wed, Feb 26, 2020 at 5:48 PM Ian Lance Taylor <i...@golang.org> wrote: > >>> > >>> On Wed, Feb 26, 2020 at 5:42 PM Michael Jones <michael.jo...@gmail.com> > >>> wrote: > >>>> > >>>> There is the BSD notion of sa_restart, a convenience to loop for the > >>>> caller as appropriate. > >>>> > >>>> https://www.freebsd.org/cgi/man.cgi?query=sigaction > >>>> > >>>> Go could adopt such a notion if desired. > >>> > >>> We already do. We install all signal handlers with the SA_RESTART flag > >>> set. > >>> > >>> Unfortunately if you peruse "man 7 signal" on a GNU/Linux system you > >>> will see a list of system calls that return EINTR even if the handler > >>> has SA_RESTART set. > >>> > >>> Ian > >>> > >>>> On Wed, Feb 26, 2020 at 5:14 PM Ian Lance Taylor <i...@golang.org> wrote: > >>>>> > >>>>> On Wed, Feb 26, 2020 at 9:11 AM Manlio Perillo > >>>>> <manlio.peri...@gmail.com> wrote: > >>>>>> > >>>>>> On Wednesday, February 26, 2020 at 4:14:38 PM UTC+1, Ian Lance Taylor > >>>>>> wrote: > >>>>>>> > >>>>>>> On Wed, Feb 26, 2020 at 7:11 AM Manlio Perillo <manlio...@gmail.com> > >>>>>>> wrote: > >>>>>>>> > >>>>>>>> On Wednesday, February 26, 2020 at 3:51:54 PM UTC+1, Peter Kleiweg > >>>>>>>> wrote: > >>>>>>>>> > >>>>>>>>> Op woensdag 26 februari 2020 13:05:40 UTC+1 schreef Manlio Perillo: > >>>>>>>>>> > >>>>>>>>>> On Wednesday, February 26, 2020 at 12:33:05 PM UTC+1, Peter > >>>>>>>>>> Kleiweg wrote: > >>>>>>>>>>> > >>>>>>>>>>> With Go version 1.14 I get a lot of errors when I run: > >>>>>>>>>>> > >>>>>>>>>>> go test -v github.com/pebbe/zmq4 > >>>>>>>>>>> > >>>>>>>>>>> I didn't see this with Go 1.13.8 or any earlier version. > >>>>>>>>>>> > >>>>>>>>>>> Is this a problem with Go 1.14, or am I doing something wrong and > >>>>>>>>>>> just got lucky until now? > >>>>>>>>>>> > >>>>>>>>>>> How do I debug this? The errors are different for each run. Below > >>>>>>>>>>> is a sample of some errors. > >>>>>>>>>>> Line numbers are not always accurate, because I inserted some > >>>>>>>>>>> calls to test.Log(). > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> The errors are probably caused by > >>>>>>>>>> https://golang.org/doc/go1.14#runtime. > >>>>>>>>>> > >>>>>>>>>> The solution is to update zmq4 to explicitly handle interrupted > >>>>>>>>>> system calls. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> Often the program freezes before I get an interrupted system call. > >>>>>>>>> It hangs inside a ZeroMQ C++ library function. > >>>>>>>>> zmq4 is just a wrapper for ZeroMQ. I can't "fix" ZeroMQ to make it > >>>>>>>>> work with Go. > >>>>>>>>> > >>>>>>>>> Is there a way to stop Go from interrupting my system calls? It > >>>>>>>>> happens rather randomly all over the place. > >>>>>>>> > >>>>>>>> > >>>>>>>> https://stackoverflow.com/questions/36040547/zeromq-how-to-react-on-different-signal-types-on-eintr > >>>>>>>> > >>>>>>>> ZeroMQ may return an EINTR error , but zmq4 does not list it in > >>>>>>>> errors.go. > >>>>>>>> ZeroMQ asks the caller to handle EINTR, so zmq4 should handle it > >>>>>>>> internally or return it to the caller. > >>>>>>>> > >>>>>>>> https://golang.org/doc/go1.14#runtime should have mentioned that not > >>>>>>>> only programs that use packages like syscall or > >>>>>>>> golang.org/x/sys/unix will see more slow system calls fail with > >>>>>>>> EINTR errors, but also programs that use Cgo. > >>>>>>> > >>>>>>> I don't know ZeroMQ. If the ZeroMQ calls correspond closely to system > >>>>>>> calls, then it could work for them to return EINTR. In that case the > >>>>>>> fix is going to be for the Go wrapper around ZeroMQ to check whether > >>>>>>> the error returned is syscall.EINTR, and to retry the call if it is. > >>>>>>> > >>>>>> > >>>>>> Unfortunately it is not that simple: > >>>>>> > >>>>>> http://250bpm.com/blog:12 > >>>>>> https://alobbs.com/post/54503240599/close-and-eintr > >>>>>> http://man7.org/linux/man-pages/man7/signal.7.html > >>>>>> https://github.com/golang/go/issues/11180 > >>>>>> https://www.python.org/dev/peps/pep-0475/ > >>>>>> > >>>>>> The second entry about close and EINTR is enlightening. > >>>>> > >>>>> Thanks for the links. Note that these issues don't really have > >>>>> anything to do with Go. For certain system calls, you need to handle > >>>>> EINTR one way or another. The Go runtime does as much as it can to > >>>>> avoid these problems, but on Unix systems it is impossible to avoid > >>>>> them entirely. > >>>>> > >>>>> 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/CAOyqgcXGcdfpPAz8t8adfqGodKPjZNxKzkTUyB0b4L1zysVFSQ%40mail.gmail.com. > >>>> > >>>> > >>>> > >>>> -- > >>>> Michael T. Jones > >>>> michael.jo...@gmail.com > >> > >> -- > >> Michael T. Jones > >> michael.jo...@gmail.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/CAOyqgcW_rGLEGY2d%3Df_OacR%3D%3DSv9kPwp%2BUN8SG3N981S1quobQ%40mail.gmail.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/CAOyqgcUdX7G1QM5o-HUVH__YUpva6X%2Bj516sqa-zrYdXu%2By-wg%40mail.gmail.com.
