Go version
go version go1.23.0 darwin/arm64
Output of go env in your module/workspace:
GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/voss/Library/Caches/go-build'
GOENV='/Users/voss/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/voss/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/voss/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.23.0'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/Users/voss/Library/Application Support/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOMOD='/Users/voss/project/pdf-issues/006-go-iter/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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/var/folders/hn/tn2k45vx3pz4v24pbmf4zl040000gn/T/go-build3862330642=/tmp/go-build -gno-record-gcc-switches -fno-common'
What did you do?
I tried to use the new range over func loops. Here is the code:
https://go.dev/play/p/rYiGIM4RaVe
This is a pared down version of a much longer program. The code here does no longer make much sense, but has no external dependencies and still shows the problem.
What did you see happen?
There are several problems with this code:
- On the playground, at https://go.dev/play/p/rYiGIM4RaVe, the code crashes with the message
fatal error: concurrent map read and map write. Note that there is no explicit concurrency in this code. The crash goes away if the print statement on line 80 is enabled.
- On my own system (an M2 MacBook Air), the same code crashes with the following error message:
unexpected fault address 0xf48d0c3a929e0
fatal error: fault
[signal SIGSEGV: segmentation violation code=0x2 addr=0xf48d0c3a929e0 pc=0x104d58a50]
- While trying to debug the problem, similar code (which I didn't keep, sorry!) sometimes triggered the panic on line 95 with impossible key values for the map
bestM.
What did you expect to see?
The code should not crash, and the absence/presence of the print statement should not change the behaviour of the program.
Go version
go version go1.23.0 darwin/arm64
Output of
go envin your module/workspace:What did you do?
I tried to use the new range over func loops. Here is the code:
https://go.dev/play/p/rYiGIM4RaVe
This is a pared down version of a much longer program. The code here does no longer make much sense, but has no external dependencies and still shows the problem.
What did you see happen?
There are several problems with this code:
fatal error: concurrent map read and map write. Note that there is no explicit concurrency in this code. The crash goes away if the print statement on line 80 is enabled.bestM.What did you expect to see?
The code should not crash, and the absence/presence of the print statement should not change the behaviour of the program.