cmd/go: "RLock …: Function not implemented" when the main module is in a filesystem that does not support locking

[ayush-dedhia25]

What version of Go are you using (go version)?

$ go version
go version go1.17.1 android/arm64

Does this issue reproduce with the latest release?

No

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/data/data/com.termux/files/home/.cache/go-build"
GOENV="/data/data/com.termux/files/home/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="android"
GOINSECURE=""
GOMODCACHE="/data/data/com.termux/files/home/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="android"
GOPATH="/data/data/com.termux/files/home/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/data/data/com.termux/files/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/data/data/com.termux/files/usr/lib/go/pkg/tool/android_arm64"
GOVCS=""
GOVERSION="go1.17.1"
GCCGO="gccgo"
AR="ar"
CC="aarch64-linux-android-clang"
CXX="aarch64-linux-android-clang++"
CGO_ENABLED="1"
GOMOD="/storage/8D8B-150E/Go/secure-api/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 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/data/data/com.termux/files/usr/tmp/go-build380772883=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I tired to create a module for my new golang project using go mod init github.com/ayush/secure-api

What did you expect to see?

I expected of successfully creation of module for my project.

What did you see instead?

Error I got:
go: RLock /storage/8D8B-150E/Go/secure-api/go.mod: function not implemented

[shmsr]

@ayush-dedhia25 I see a similar query of yours was already answered on StackOverflow and even by a member of a Go Team (@bcmills) and still you have opened an issue here.

Refer: https://stackoverflow.com/a/68728663/5821408

[bcmills]

I explicitly mentioned the possibility of filing an issue on the SO answer:

If you can't configure the filesystem to support locking and it isn't practical for you to work within a different filesystem that does, please file an issue at https://golang.org/issue/new, and mention issue #37461 (which is closely related) in the issue description.

So I think it's fine to keep this issue open. Honestly, I think we should probably proceed without file-locking when the go.mod and go.sum files cannot be locked — they're less prone to race conditions than, say, the module cache (which must support file-locking because it is much harder to fix if it becomes corrupted, and is implicitly modified much more frequently).

[bcmills]

Locking the go.mod and go.sum files also interferes with certain gopls behaviors (see #50971, #50840). (CC @findleyr, @hyangah)

Now that the go command defaults to -mod=readonly, I wonder if this file-locking has outlived its usefulness. Maybe we should stop using file-locking in the main module (and only use it within the module cache). (CC @matloob)

On the other hand, the locking errors that show up in the gopls tests are probably actual real/write races, and they can probably at least show up as corrupted diagnostics in actual use. 🤔

[ianlancetaylor]

@bcmills @matloob This issue is marked for 1.19. Should it move to Backlog? Thanks.