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testing: data race with parallel fuzzing #50488
Description
What version of Go are you using (go version)?
go version devel go1.18-40afced8d7 Fri Jan 7 02:37:20 2022 +0000 darwin/arm64
What operating system and processor architecture are you using (go env)?
go env Output
GO111MODULE="" GOARCH="arm64" GOBIN="" GOCACHE="/Users/aleksi/Library/Caches/go-build" GOENV="/Users/aleksi/Library/Application Support/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="arm64" GOHOSTOS="darwin" GOINSECURE="" GOMODCACHE="/Users/aleksi/Soft/GOPATH/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="darwin" GOPATH="/Users/aleksi/Soft/GOPATH" GOPRIVATE="" GOPROXY="https://proxy.golang.org" GOROOT="/Users/aleksi/Soft/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/Users/aleksi/Soft/go/pkg/tool/darwin_arm64" GOVCS="" GOVERSION="devel go1.18-40afced8d7 Fri Jan 7 02:37:20 2022 +0000" GCCGO="gccgo" AR="ar" CC="clang" CXX="clang++" CGO_ENABLED="1" GOMOD="/Users/aleksi/Code/My/go-bug/new/go.mod" 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/8p/0cm9052d7pd0smp13_35z0440000gn/T/go-build4037385395=/tmp/go-build -gno-record-gcc-switches -fno-common"
What did you do?
https://github.com/AlekSi/go-bug/tree/master/50488
func Fuzz1(f *testing.F) {
f.Add(42)
f.Add(43)
f.Fuzz(func(t *testing.T, i int) {
t.Parallel()
})
}go test -fuzz=Fuzz2 -race
(note: Fuzz2, not Fuzz1 as in code)
What did you expect to see?
Error about missing Fuzz2.
What did you see instead?
==================
WARNING: DATA RACE
Write at 0x00c0000ca000 by goroutine 8:
internal/fuzz.SnapshotCoverage()
/Users/aleksi/Soft/go/src/internal/fuzz/coverage.go:32 +0xb8
testing/internal/testdeps.TestDeps.SnapshotCoverage()
/Users/aleksi/Soft/go/src/testing/internal/testdeps/deps.go:198 +0x38
testing/internal/testdeps.(*TestDeps).SnapshotCoverage()
<autogenerated>:1 +0x24
testing.(*F).Fuzz.func1.1.1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:330 +0x48
runtime.deferreturn()
/Users/aleksi/Soft/go/src/runtime/panic.go:436 +0x34
testing.tRunner()
/Users/aleksi/Soft/go/src/testing/testing.go:1440 +0x18c
testing.(*F).Fuzz.func1.2()
/Users/aleksi/Soft/go/src/testing/fuzz.go:321 +0x44
Previous write at 0x00c0000ca000 by goroutine 9:
internal/fuzz.SnapshotCoverage()
/Users/aleksi/Soft/go/src/internal/fuzz/coverage.go:32 +0xb8
testing/internal/testdeps.TestDeps.SnapshotCoverage()
/Users/aleksi/Soft/go/src/testing/internal/testdeps/deps.go:198 +0x38
testing/internal/testdeps.(*TestDeps).SnapshotCoverage()
<autogenerated>:1 +0x24
testing.(*F).Fuzz.func1.1.1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:330 +0x48
runtime.deferreturn()
/Users/aleksi/Soft/go/src/runtime/panic.go:436 +0x34
testing.tRunner()
/Users/aleksi/Soft/go/src/testing/testing.go:1440 +0x18c
testing.(*F).Fuzz.func1.2()
/Users/aleksi/Soft/go/src/testing/fuzz.go:321 +0x44
Goroutine 8 (running) created at:
testing.(*F).Fuzz.func1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:321 +0x7dc
testing.(*F).Fuzz()
/Users/aleksi/Soft/go/src/testing/fuzz.go:396 +0xc68
github.com/AlekSi/go-bug/new.Fuzz1()
/Users/aleksi/Code/My/go-bug/new/bug_test.go:11 +0xb0
testing.fRunner()
/Users/aleksi/Soft/go/src/testing/fuzz.go:695 +0xfc
testing.runFuzzTests.func1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:515 +0x44
Goroutine 9 (running) created at:
testing.(*F).Fuzz.func1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:321 +0x7dc
testing.(*F).Fuzz()
/Users/aleksi/Soft/go/src/testing/fuzz.go:396 +0xc68
github.com/AlekSi/go-bug/new.Fuzz1()
/Users/aleksi/Code/My/go-bug/new/bug_test.go:11 +0xb0
testing.fRunner()
/Users/aleksi/Soft/go/src/testing/fuzz.go:695 +0xfc
testing.runFuzzTests.func1()
/Users/aleksi/Soft/go/src/testing/fuzz.go:515 +0x44
==================
exit status 66
That reproducer is reduced from a much bigger example (but with the same race stack trace) in which or maybe not.Fuzz2 actually exists
Activity
AlekSi commentedon Jan 7, 2022
@gopherbot fuzz
gopherbot commentedon Jan 7, 2022
Change https://golang.org/cl/376254 mentions this issue:
internal/fuzz: fix racing in SnapshotCoveragemengzhuo commentedon Jan 7, 2022
@AlekSi I've upload a CL for this issue, PTAL.
gopherbot commentedon Jan 7, 2022
Change https://golang.org/cl/376554 mentions this issue:
testing: only snapshot coverage during fuzzingAlekSi commentedon Jan 8, 2022
@rolandshoemaker It looks like this CL only added a benchmark. I guess you forgot to add changed files.
rolandshoemaker commentedon Jan 10, 2022
Whoops yup, pushed the right change.
gopherbot commentedon Jan 11, 2022
Change https://golang.org/cl/377634 mentions this issue:
cmd/go: skip TestScript/test_fuzz_test_race on !racecmd/go: skip TestScript/test_fuzz_test_race on !race
testing: only snapshot coverage during fuzzing
cmd/go: skip TestScript/test_fuzz_test_race on !race
testing: only snapshot coverage during fuzzing