math/rand: panic generating NormFloat64 #66086
Description
Go version
go 1.20.5
Output of go env in your module/workspace:
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOENV="/home/user/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/user/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/user/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/user/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/user/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/user/go/src/lava/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build4204543259=/tmp/go-build -gno-record-gcc-switches"What did you do?
firstly we generate a global random instance:
// rand wrapper for protocol structs which hosts the same seed for deterministic unified random distribution
// we set the seed once for the entire process.
var protocolRand *rand.Rand
func Initialized() bool {
return protocolRand != nil
}
func InitRandomSeed() {
seed := time.Now().UnixNano()
protocolRand = rand.New(rand.NewSource(seed))
}And later on we are running:
func pertrubWithNormalGaussian(orig, percentage float64) float64 {
perturb := rand.NormFloat64() * percentage * orig
return orig + perturb
} generating the float caused our application to panic, Important to note this is very rare we used this method probably millions of times before it crashed.
What did you see happen?
panic: runtime error: index out of range [-1]
goroutine 18216 [running]:
math/rand.(*rngSource).Uint64(...)
math/rand/rng.go:249
math/rand.(*rngSource).Int63(0x4d7c6d00?)
math/rand/rng.go:234 +0x92
math/rand.(*Rand).Int63(...)
math/rand/rand.go:95
math/rand.(*Rand).Uint32(...)
math/rand/rand.go:98
math/rand.(*Rand).NormFloat64(0xc0015f7a40)
math/rand/normal.go:39 +0x35
github.com/lavanet/lava/utils/rand.NormFloat64(...)
github.com/lavanet/lava/utils/rand/rand.go:71
What did you expect to see?
Getting a random float without a panic :)