Proposal Details

Now asyncpreemptoff=1 cannot be specified by //go:debug:

examples\test\main.go:1:1: invalid //go:debug: unknown //go:debug setting "asyncpreemptoff"

However, there are many situations where disabling async preemption is required as a workaround to make applications work correctly:

• runtime: async preemption support on ARM64 breaks ARM64 on QEMU #36981
• runtime: hangs on windows with golang >= 1.14 #48059
• cmd/cgo: does not compile for iOS simulator arm64 #57442
• runtime: rare stack corruption on Go 1.20 and later #64781
• runtime: stalls under Rosetta2 with MacOS 14.5  #68485
• runtime: a Windows application launched via Steam sometimes freezes #71242
• terraform destroy command is not working and seems to be hanging on Mac OS Big Sur  hashicorp/terraform#27350

I propose to enable to specify asyncpreemptoff=1 as //go:debug and godebug section in go.mod.

Note that it is still possible to specify it by -ldflags="-X=runtime.godebugDefault=asyncpreemptoff=1", but this is pretty hacky.