go: runtime: handling of CTRL_CLOSE_EVENT seems broken

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

go version go1.15.2 windows/amd64

Does this issue reproduce with the latest release?

Yes.

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

set GO111MODULE= set GOARCH=amd64 set GOBIN=D:\Apps\Go\work\bin set GOCACHE=C:\Users\ncruc\AppData\Local\go-build set GOENV=C:\Users\ncruc\AppData\Roaming\go\env set GOEXE=.exe set GOFLAGS= set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOINSECURE= set GOMODCACHE=D:\Apps\Go\work\pkg\mod set GONOPROXY= set GONOSUMDB= set GOOS=windows set GOPATH=D:\Apps\Go\work set GOPRIVATE= set GOPROXY=https://proxy.golang.org,direct set GOROOT=D:\Apps\Go\root set GOSUMDB=sum.golang.org set GOTMPDIR= set GOTOOLDIR=D:\Apps\Go\root\pkg\tool\windows_amd64 set GCCGO=gccgo set AR=ar set CC=gcc set CXX=g++ set CGO_ENABLED=1 set GOMOD= set CGO_CFLAGS=-g -O2 set CGO_CPPFLAGS= set CGO_CXXFLAGS=-g -O2 set CGO_FFLAGS=-g -O2 set CGO_LDFLAGS=-g -O2 set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\ncruc\AppData\Local\Temp\go-build526790066=/tmp/go-build -gno-record-gcc-switches

What did you do?

I have a MCVE on https://gist.github.com/ncruces/20dbdc73d0da6e211ee56b68c2240bae

Open a new console window, build and run the example. Then close the console window and check the log file it creates next to the executable.

go build -o sig.exe gist.github.com/ncruces/20dbdc73d0da6e211ee56b68c2240bae.git
sig.exe

What did you expect to see?

Given cl/187739 has been merged, I expected to see a SIGTERM being received by signal.Notify, and having 5 to 20s to handle cleanup.

Specifically I want to see these log lines:

2020/10/09 13:36:31 Cleaning up...
2020/10/09 13:36:32 Exited

What did you see instead?

Either SIGTERM isn’t being received at all, or we’re not given any time to cleanup.

---

The MCVE also includes code to call SetConsoleCtrlHandler (which shouldn’t be needed given cl/187739).

You can activate it by running either of:

sig.exe -handle
sig.exe -handle -block

The MCVE works consistently if the handler blocks giving the rest of the program time to gracefully terminate.

This is consistent with the documentation:

• https://docs.microsoft.com/en-us/windows/console/handlerroutine
• https://docs.microsoft.com/en-us/windows/console/setconsolectrlhandler

So, I’m assuming that’s what needs to be changed, this return needs to become a select {} or similar:

https://github.com/golang/go/blob/c0dded04f7ded5048b44200078a1f723f5e1bcc1/src/runtime/os_windows.go#L1010-L1012

I could easily do a PR, but I’m not well versed with building go from source and testing the change.

Maybe commenters from #7479 can help: @alexbrainman, @tianon?