Skip to content

runtime: deadlock detector false positive on Windows #56989

Closed as not planned
Closed as not planned
@9072997

Description

@9072997

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

go version go1.19.3 windows/amd64

Does this issue reproduce with the latest release?

I believe 1.19.3 to be the latest release at the moment, so yes.

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

go env Output
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\jpenn\AppData\Local\go-build
set GOENV=C:\Users\jpenn\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\jpenn\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\jpenn\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:\Program Files\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.19.3
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=L:\Work\scratch\tmp\deadlock-example\go.mod
set GOWORK=
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 -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=C:\Users\jpenn\AppData\Local\Temp\go-build4217524297=/tmp/go-build -gno-record-gcc-switches

What did you do?

deadlock-example.zip

See the attached zip file. There are 4 versions of the same program. Version A triggers the deadlock detector. I wanted to test this program with the deadlock detector disabled but AFAIK there is no explicit way to do that, so I created 3 other versions of the program (B, C, and D from the zip file) which avoid the deadlock detector in various ways.

  • Version A is the original version of the program which causes the false positive deadlock detection
  • Version B does include "C", which as far as I can tell, disables the deadlock detector, even if there is no actual C code. This version of the program works as expected, proving that it is not a true deadlock.
  • Version C of the program "distracts" the deadlock detector by starting a 2nd goroutine that does time.Sleep() in a loop. This version of the program works as expected.
  • Version D of the program "distracts" the deadlock detector by starting a TCP listener on a random port in a 2nd goroutine. This version of the program works as expected.

What did you expect to see?

Watching for events...
got an event
got an event
got an event

Note that you do have to wait for something on your Windows computer to actually generate an event. Manually checking for Windows updates is a fairly easy way to trigger one, though be warned the button to check for updates is de-bounced to about once per minute.

What did you see instead?

Watching for events...
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [select]:
main.main()
        L:/Work/scratch/tmp/deadlock-example/a/version-a.go:19 +0x167
exit status 2

Metadata

Metadata

Assignees

No one assigned

    Labels

    FrozenDueToAgeNeedsInvestigationSomeone must examine and confirm this is a valid issue and not a duplicate of an existing one.OS-Windowscompiler/runtimeIssues related to the Go compiler and/or runtime.

    Type

    No type

    Projects

    No projects

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions