This code is extracted from something real. Someone on the team noticed the unit tests (which I wrote on a Linux machine) were failing on their Windows machine. I'll continue studying this and come back if I find something new.
Thank you both for your time, I appreciate it! On Friday, May 4, 2018 at 11:42:00 PM UTC+3, speter wrote: > > To file a bug (and have it treated seriously) you would need to > demonstrate that it is causing problems in a program that actually does > something useful, not just a pathological code sample. My expectation would > be that once you start doing some real processing, the difference between > time.Now() invocations becomes non-zero, that is this "issue" doesn't > reproduce with "real" practical programs. > > > On Fri, May 4, 2018 at 10:26 PM, Andrei Avram <[email protected] > <javascript:>> wrote: > >> But I don't think it is because Windows is so much faster than Linux >>> >> >> Yeah... :) I was exploring all cases. >> >> >> and/or the way the time package implemented is different between Windows >>> and Linux >> >> >> Could this be considered a possible Go bug and would it worth opening an >> issue on Github? >> >> >> On Friday, May 4, 2018 at 10:57:46 PM UTC+3, speter wrote: >>> >>> So on Linux it's working as expected. In the playground time is >>> "virtual"; the start time is fixed and it doesn't progress unless you >>> explicitly Sleep -- because you don't Sleep in your program, time.Now() >>> returns the same time on both invocation. >>> >>> So the only slightly surprising part is that on Windows, time as >>> measured by time.Now() doesn't progress between the two statements. But I >>> don't think it is because Windows is so much faster than Linux. :) I'd >>> guess this is because the way Windows manages time is different from how >>> Linux manages it, and/or the way the time package implemented is different >>> between Windows and Linux. The result of the cross-platform differences >>> seems to be less precision on Windows -- at least in this specific scenario. >>> >>> Peter >>> >>> >>> On Fri, May 4, 2018 at 9:33 PM, Andrei Avram <[email protected]> >>> wrote: >>> >>>> Peter and Ian, you are both wright regarding the printing. Still, on >>>> Linux I have different values than on Go Playground. >>>> >>>> Regarding the speed, Peter, do you think that on Windows the two calls >>>> just run faster every time? >>>> >>>> On Friday, May 4, 2018 at 9:07:15 PM UTC+3, speter wrote: >>>>> >>>>> b is slightly less than 3 because there is a bit of time between the >>>>> two calls to time.Now(). >>>>> >>>>> If you substitute this: >>>>> fmt.Printf("input: %20.18f\n", b) >>>>> >>>>> you get something like >>>>> input: 2.999999965553350911 >>>>> >>>>> HTH >>>>> Peter >>>>> >>>>> On Fri, May 4, 2018 at 7:26 PM, Andrei Avram <[email protected]> >>>>> wrote: >>>>> >>>>>> Hello everyone, >>>>>> >>>>>> Today I ran into a situation that is strange to me. I ran the >>>>>> following code on two Linux machines (go run floor.go), on two Windows >>>>>> ones, and on Go Playground. >>>>>> >>>>>> package main >>>>>> >>>>>> import ( >>>>>> "time" >>>>>> "math" >>>>>> ) >>>>>> >>>>>> func main() { >>>>>> datetime := time.Now().Add(time.Hour * 24 * 7 * 4 * 12 * 3) >>>>>> seconds := -1 * int(time.Now().Sub(datetime).Seconds()) >>>>>> a := 29030400 >>>>>> b := float64(seconds) / float64(a) >>>>>> >>>>>> println("input:", b) >>>>>> println("floor:", math.Floor(b)) >>>>>> } >>>>>> >>>>>> On Linux the output is: >>>>>> >>>>>> input: +3.000000e+000 >>>>>> floor: *+2.000000e+000* >>>>>> >>>>>> On Windows and Playground: >>>>>> >>>>>> input: +3.000000e+000 >>>>>> floor: *+3.000000e+000* >>>>>> >>>>>> As you can see, on Linux the floor value of float value 3 is rounded >>>>>> down to 2, while on Windows/Playground it's 3. >>>>>> >>>>>> The code was ran with Go 1.10 and 1.10.2. >>>>>> >>>>>> The system details of one of the Linux machines, as reported by "go >>>>>> bug": >>>>>> >>>>>> go version go1.10.2 linux/amd64 >>>>>> GOARCH="amd64" >>>>>> GOBIN="" >>>>>> GOCACHE="/home/msd/.cache/go-build" >>>>>> GOEXE="" >>>>>> GOHOSTARCH="amd64" >>>>>> GOHOSTOS="linux" >>>>>> GOOS="linux" >>>>>> GOPATH="/home/msd/go/" >>>>>> GORACE="" >>>>>> GOROOT="/usr/local/go" >>>>>> GOTMPDIR="" >>>>>> GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64" >>>>>> GCCGO="gccgo" >>>>>> CC="gcc" >>>>>> CXX="g++" >>>>>> CGO_ENABLED="1" >>>>>> CGO_CFLAGS="-g -O2" >>>>>> CGO_CPPFLAGS="" >>>>>> CGO_CXXFLAGS="-g -O2" >>>>>> CGO_FFLAGS="-g -O2" >>>>>> CGO_LDFLAGS="-g -O2" >>>>>> PKG_CONFIG="pkg-config" >>>>>> GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 >>>>>> -fdebug-prefix-map=/tmp/go-build304261270=/tmp/go-build >>>>>> -gno-record-gcc-switches" >>>>>> GOROOT/bin/go version: go version go1.10.2 linux/amd64 >>>>>> GOROOT/bin/go tool compile -V: compile version go1.10.2 >>>>>> uname -sr: Linux 4.13.0-37-generic >>>>>> Distributor ID: Ubuntu >>>>>> Description: Ubuntu 16.04.4 LTS >>>>>> Release: 16.04 >>>>>> Codename: xenial >>>>>> /lib/x86_64-linux-gnu/libc.so.6: GNU C Library (Ubuntu GLIBC >>>>>> 2.23-0ubuntu10) stable release version 2.23, by Roland McGrath et al. >>>>>> gdb --version: GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1 >>>>>> >>>>>> >>>>>> Is there something I miss or could this be an issue? >>>>>> >>>>>> Thanks, >>>>>> Andrei >>>>>> >>>>>> -- >>>>>> 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 [email protected]. >>>>>> 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 [email protected]. >>>> 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 [email protected] <javascript:>. >> 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. 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