On Sun, 2 Oct 2022 10:41:17 +1100 Rob Pike <r...@golang.org> wrote: > When running coverage in a concurrent program, use the -mode=atomic > flag to avoid data races in the counters. This unavoidably has a > significant performance hit, but it should resolve this race. > > -rob >
This flag print "no test files" when running go test,
$ GOEXPERIMENT=coverageredesign CGO_ENABLED=1 go test -mode=atomic -race
-coverprofile=cover.out ./lib/dns
? github.com/shuLhan/share [no test files]
Not sure I am using the flag correctly or not since I cannot find it in
the current documentation [1].
[1] https://pkg.go.dev/cmd/go
>
> On Sun, Oct 2, 2022 at 5:10 AM Shulhan <m.shul...@gmail.com> wrote:
>
> > Hi gophers,
> >
> > The latest Go tip always fail with data race when running with -race
> > and -coverprofile options.
> >
> > Here is an example of data race output,
> >
> > ----
> > $ CGO_ENABLED=1 go test -failfast -race -count=1
> > -coverprofile=cover.out ./...
> > ...
> > ==================
> > WARNING: DATA RACE
> > Read at 0x000001e5f04c by main goroutine:
> >
> > internal/coverage/encodecounter.(*CoverageDataWriter).writeCounters.func2()
> > /home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:261
> > +0x11c
> > runtime/coverage.(*emitState).VisitFuncs()
> > /home/ms/opt/go/src/runtime/coverage/emit.go:539 +0x6bc
> > internal/coverage/encodecounter.(*CoverageDataWriter).writeCounters()
> > /home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:268
> > +0x16f
> > internal/coverage/encodecounter.(*CoverageDataWriter).AppendSegment()
> > /home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:175
> > +0x8ea
> > internal/coverage/encodecounter.(*CoverageDataWriter).Write()
> > /home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:71
> > +0x97
> > runtime/coverage.(*emitState).emitCounterDataFile()
> > /home/ms/opt/go/src/runtime/coverage/emit.go:573 +0x91
> > runtime/coverage.emitCounterDataToDirectory()
> > /home/ms/opt/go/src/runtime/coverage/emit.go:322 +0x310
> > runtime/coverage.processCoverTestDir()
> > /home/ms/opt/go/src/runtime/coverage/testsupport.go:39 +0x1c4
> > main.coverTearDown()
> > _testmain.go:179 +0x159
> > testing.coverReport2()
> > /home/ms/opt/go/src/testing/newcover.go:37 +0xcb
> > testing.coverReport()
> > /home/ms/opt/go/src/testing/cover.go:83 +0xc74
> > testing.(*M).writeProfiles()
> > /home/ms/opt/go/src/testing/testing.go:2053 +0xc6f
> > testing.(*M).after.func1()
> > /home/ms/opt/go/src/testing/testing.go:1987 +0x30
> > sync.(*Once).doSlow()
> > /home/ms/opt/go/src/sync/once.go:74 +0x101
> > sync.(*Once).Do()
> > /home/ms/opt/go/src/sync/once.go:65 +0x46
> > testing.(*M).after()
> > /home/ms/opt/go/src/testing/testing.go:1986 +0x55
> > testing.(*M).Run.func4()
> > /home/ms/opt/go/src/testing/testing.go:1761 +0x39
> > runtime.deferreturn()
> > /home/ms/opt/go/src/runtime/panic.go:476 +0x32
> > testing.(*M).Run()
> > /home/ms/opt/go/src/testing/testing.go:1771 +0xbb3
> > github.com/shuLhan/share/lib/dns.TestMain()
> > /home/ms/go/src/github.com/shuLhan/share/lib/dns/dns_test.go:63
> > +0x5db
> > main.main()
> > _testmain.go:192 +0x33d
> >
> > Previous write at 0x000001e5f04c by goroutine 9:
> > sync/atomic.AddInt32()
> > /home/ms/opt/go/src/runtime/race_amd64.s:281 +0xb
> > sync/atomic.AddUint32()
> > <autogenerated>:1 +0x1a
> > github.com/shuLhan/share/lib/dns.(*Server).processRequest()
> > /home/ms/go/src/github.com/shuLhan/share/lib/dns/server.go:593
> > +0xc67
> > github.com/shuLhan/share/lib/dns.(*Server).ListenAndServe.func1()
> > /home/ms/go/src/github.com/shuLhan/share/lib/dns/server.go:187
> > +0x39
> >
> > Goroutine 9 (running) created at:
> > github.com/shuLhan/share/lib/dns.(*Server).ListenAndServe()
> > /home/ms/go/src/github.com/shuLhan/share/lib/dns/server.go:187
> > +0xe6 github.com/shuLhan/share/lib/dns.TestMain.func1()
> > /home/ms/go/src/github.com/shuLhan/share/lib/dns/dns_test.go:54
> > +0x44
> > ==================
> > ...
> > ----
> >
> > There are many lines like that with the same pattern.
> >
> > In the above snippet, the lib/dns/dns_test.go:63 point this code
> > [1],
> >
> > os.Exit(m.Run())
> >
> > So it does not make sense if the data race is in my code.
> >
> > A quick bisect point to this commit [2].
> >
Just want to be clear, I run the test using
GOEXPERIMENT=coverageredesign flag using Go tip commit 53773a5d08
$ go version
go version devel go1.20-53773a5d08 Wed Sep 28 11:50:58 2022 +0000
linux/amd64
Without GOEXPERIMENT flag,
$ CGO_ENABLED=1 go test -race -coverprofile=cover.out ./lib/dns
ok github.com/shuLhan/share/lib/dns 0.707s coverage: 56.8% of
statements
With GOEXPERIMENT=coverageredesign flag,
----
$ GOEXPERIMENT=coverageredesign CGO_ENABLED=1 go test -race ./lib/dns
ok github.com/shuLhan/share/lib/dns 0.683s
$ GOEXPERIMENT=coverageredesign CGO_ENABLED=1 go test -race
-coverprofile=cover.out ./lib/dns
dns.Server: listening for DNS over TLS at 127.0.0.1:18053
dns.Server: listening for DNS over TCP at 127.0.0.1:5300
dns.Server: listening for DNS over UDP at 127.0.0.1:5300
dns.Server: listening for DNS over HTTPS at 127.0.0.1:8443
dns: invalid IP address "localhost"
dns: invalid name server URI "://127.0.0.1"
dns: invalid IP address "localhost:53"
dns: invalid IP address "localhost:53"
PASS
==================
WARNING: DATA RACE
Read at 0x000001e5f04c by main goroutine:
internal/coverage/encodecounter.(*CoverageDataWriter).writeCounters.func2()
/home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:261 +0x11c
runtime/coverage.(*emitState).VisitFuncs()
/home/ms/opt/go/src/runtime/coverage/emit.go:539 +0x6bc
internal/coverage/encodecounter.(*CoverageDataWriter).writeCounters()
/home/ms/opt/go/src/internal/coverage/encodecounter/encode.go:268 +0x16f
...
----
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