runtime, x/mobile: SIGABRT ABORT, runtime.raise_trampoline.abi0 + 462 (sys_darwin_arm64.s:462) for Mac Catalyst targets running on arm64

[CatStudioApp]

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

$ go version
go version go1.18 darwin/arm64

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="arm64"
GOBIN=""
GOCACHE="/Users/[user]/Library/Caches/go-build"
GOENV="/Users/[user]/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/[user]/golang/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/[user]/golang"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/opt/homebrew/Cellar/go/1.18/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/opt/homebrew/Cellar/go/1.18/libexec/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/cd/j79005393f7_zbyjw3zpkrlc0000gn/T/go-build3399080997=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I delivered my app continuously using Gomobile to MacCatalyst target. Starting from Go 1.18, my app started to have such a crash:

Crashed: Thread #1
SIGABRT ABORT 0x0000000186370db8
Crashed: Thread
0  libsystem_kernel.dylib         0x9db8 __pthread_kill + 8
1  libsystem_pthread.dylib        0x6ee0 pthread_kill + 288
2  libsystem_c.dylib              0x42674 raise + 32
3  [my_app_target_with_gomobile]                      0x189104 runtime.raise_trampoline.abi0 + 462 (sys_darwin_arm64.s:462)
4  [my_app_target_with_gomobile]                      0x187ee8 runtime.asmcgocall.abi0 + 1094 (asm_arm64.s:1094)
5  ???                            0xed65f03c0 (Missing)

What did you expect to see?

No crash

What did you see instead?

Crashes

[cherrymui]

Catalyst isn't a supported target for Go yet. See #47228 (comment)

[CatStudioApp]

@cherrymui we have actually been using Gomobile for Catalyst for over six months and this crash only appeared after Go 1.18…

[jiangzhiguo1992]

@CatStudioApp I also encountered the same problem, any follow-up?

[stffabi]

I've seen the exact same problem for our app when upgrading from Go 1.17 to 1.18 and building for catalyst. Our app has run without any problem for about 2 years on catalyst.

Bisecting Go 1.17 and Go 1.18 releases showed the problem is caused by the commit a4b2c57 that was used to fix this issue #49288

Would be interesting if someone of the Go team could maybe bring some light up into this. For catalyst is GOOS=darwin, so it seems like somehow macOS does not like the async preemption signal handling when running in catalyst mode.

[cherrymui]

If you want to disable async preemption, you could try setting the environment variable GODEBUG=asyncpreemptoff=1.

Is the preemption signal the only issue, or signals in general? Could you try sending some signals to you program, and see if that works? It would be good to know why preemption signals don't work in catalyst mode.

[stffabi]

Thanks so much @cherrymui for your reply.

If you want to disable async preemption, you could try setting the environment variable GODEBUG=asyncpreemptoff=1.

This is pretty hard to achieve because in my case the Go code runs in a network extension started by the network extension framework. But I patched Go to internally set debug.asyncpreemptoff = 1 and that fixed the issue.

Is the preemption signal the only issue, or signals in general? Could you try sending some signals to you program, and see if that works?

I tried sending SIGURG (which is used for preemption according to signal_unix.go) and that did not crash the app, I also tried SIGWINCH which also did not crash the app. (Edit: when asyncpreemptoff was off)

Commit a4b2c57 seems to only install the sighandler also for const sigPreempt = _SIGURG. I don't really know the runtime code, but from the brief look I took into it I would suspect the preempt signal is send regardless of that commit. But without that commit it is just ignored and not handled because sighandler is not installed.