Closed
Description
What version of Go are you using (go version)?
$ go version go version devel go1.19-45f45444b3 Sat Mar 5 21:20:16 2022 +0000 linux/amd64 go version go1.17.8 linux/amd64 go version go1.15.15 linux/amd64
Does this issue reproduce with the latest release?
Yes.
What operating system and processor architecture are you using (go env)?
go env Output
$ go env GO111MODULE="" GOARCH="amd64" GOBIN="" GOCACHE="/home/dominikh/.cache/go-build" GOENV="/home/dominikh/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/home/dominikh/prj/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/home/dominikh/prj" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/home/dominikh/prj/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/home/dominikh/prj/go/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.17.8" GCCGO="gccgo" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/home/dominikh/prj/src/honnef.co/go/bittorrent/go.mod" 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-build2412946897=/tmp/go-build -gno-record-gcc-switches"
What did you do?
Run
package main
import "os"
func main() {
buf := make([]byte, 1)
f, err := os.Open("/dev/urandom")
if err != nil {
panic(err)
}
go func() {
for {
n, err := f.ReadAt(buf, 0)
if err != nil || n == 0 {
panic(err)
}
}
}()
for {
println(buf[0])
}
}
with GORACE=halt_on_error=1 go run -race foo.go
What did you expect to see?
I expect the race detector to flag the race.
What did you see instead?
The race detector misses the race and we get an infinite stream of random bytes.
Using Read instead of ReadAt almost immediately flags the race. The issue isn't specific to the file being opened. It happens just the same with files in /proc or actual files on a hard drive.
/cc @golang/runtime