libFuzzer's fuzzer-finalstats.test seems flaky on the sanitizer bots

Runtimes Sanitizers
1

The sanitizer-x86_64-linux bot has been failing intermittently on fuzzer-finalstats.test recently, and possibly for quite some time:

The failure looks like this:

/b/sanitizer-x86_64-linux/build/llvm-project/compiler-rt/test/fuzzer/fuzzer-finalstats.test:10:15: error: FINAL_STATS1: expected string not found in input
FINAL_STATS1: stat::number_of_executed_units: 33
              ^
<stdin>:1:1: note: scanning from here
INFO: Running with entropic power schedule (0xFF, 100).
^
<stdin>:12:1: note: possible intended match here
stat::number_of_executed_units: 34
^

Has anyone seen anything like this locally? Is there someone who can investigate what’s going wrong here?

2

Hey Justin, thanks for the heads up. I’ll take a look. The entropic strategy makes it a bit more challenging to design tests, given that it’s dependent on execution speed of inputs for mutation priority.

1 Like
3

Found it - [libfuzzer] Fix -runs=X flaky test (fuzzer-finalstats.test) by hctim · Pull Request #96914 · llvm/llvm-project · GitHub is the fix. Thanks again for bringing it to my attention. I think I’d noticed it flake once but our weekly rotation can miss some of the super intermittent issues.

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