internal/fuzz: don't deflake coverage found while fuzzing
Previously, the worker would attempt to deflake
an input that was reported to have caused new
coverage. The chances of a flake causing new
coverage seem pretty low to me, and even if it
was a flake that caused it, adding that input to
the cache doesn't seem like a bad thing. The
input is already going to be deflaked during
minimization anyway. If by some off-chance the
code is causing a lot of flaky coverage
increases, and the user doesn't want minimization
to occur, then setting -fuzzminimizetime=1x will
deflake in the way they want without minimizing.
This can be documented as needed.
This fixes a bug where the mem.header().count
could have been one too large if an unrecoverable
crash occured while deflaking an input that
caused code coverage.
Fixes #49047
Change-Id: Ibdf893d7a89a46dd700702afb09e35623615390e
Reviewed-on: https://go-review.googlesource.com/c/go/+/358094
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Julie Qiu <julie@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/src/cmd/go/testdata/script/test_fuzz_mutator_repeat.txt b/src/cmd/go/testdata/script/test_fuzz_mutator_repeat.txt
index f2952c3..15d7cb6 100644
--- a/src/cmd/go/testdata/script/test_fuzz_mutator_repeat.txt
+++ b/src/cmd/go/testdata/script/test_fuzz_mutator_repeat.txt
@@ -1,5 +1,3 @@
-skip # Flaky: https://golang.org/issue/49047
-
# TODO(jayconrod): support shared memory on more platforms.
[!darwin] [!linux] [!windows] skip
@@ -9,11 +7,11 @@
[short] skip
-# Start fuzzing. The worker crashes after ~100 iterations.
+# Start fuzzing. The worker crashes after 100 iterations.
# The fuzz function writes the crashing input to "want" before exiting.
# The fuzzing engine reconstructs the crashing input and saves it to testdata.
! exists want
-! go test -fuzz=. -parallel=1
+! go test -fuzz=. -parallel=1 -fuzztime=110x -fuzzminimizetime=10x -v
stdout 'fuzzing process terminated unexpectedly'
stdout 'Crash written to testdata'
@@ -46,12 +44,20 @@
if i == 100 {
f, err := os.OpenFile("want", os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
if err != nil {
- // Couldn't create the file, probably because it already exists,
- // and we're minimizing now. Return without crashing.
- return
+ // Couldn't create the file. Return without crashing, and try
+ // again.
+ i--
+ t.Skip(err)
}
- f.Write(b)
- f.Close()
+ if _, err := f.Write(b); err != nil {
+ // We already created the file, so if we failed to write it
+ // there's not much we can do. The test will fail anyway, but
+ // at least make sure the error is logged to stdout.
+ t.Fatal(err)
+ }
+ if err := f.Close(); err != nil {
+ t.Fatal(err)
+ }
os.Exit(1) // crash without communicating
}
diff --git a/src/internal/fuzz/worker.go b/src/internal/fuzz/worker.go
index b36ebe2..388675f 100644
--- a/src/internal/fuzz/worker.go
+++ b/src/internal/fuzz/worker.go
@@ -738,20 +738,9 @@
return resp
}
if cov != nil {
- // Found new coverage. Before reporting to the coordinator,
- // run the same values once more to deflake.
- if !shouldStop() {
- dur, cov, errMsg = fuzzOnce(entry)
- if errMsg != "" {
- resp.Err = errMsg
- return resp
- }
- }
- if cov != nil {
- resp.CoverageData = cov
- resp.InterestingDuration = dur
- return resp
- }
+ resp.CoverageData = cov
+ resp.InterestingDuration = dur
+ return resp
}
if shouldStop() {
return resp
