ci: Bump fuzz task timeout #31814

1. 
   maflcko commented at 9:18 pm on February 6, 2025: member

   The fuzz task seems to be the most CPU intense task (going through GB of data through all fuzz inputs for all fuzz targets).

   Normally, the task takes 44 minutes (example https://cirrus-ci.com/task/5077976091459584), but under higher load, it may take longer (https://cirrus-ci.com/task/5966231095738368).

   I tried to move it to GHA to see how it compares, but it will be even slower there: https://github.com/maflcko/bitcoin-core-with-ci/actions/runs/13182526514/job/36796629409.

   The CI machines were recently updated to increase the CI performance, so in theory they could be updated again, but this can take some time and seems like the wrong fix anyway, because it will just hide the problem:

   Ideally fuzzing is fast and when evaluating a fuzz input takes more than 10 seconds, it feels more like a slow unit test loop. So ideally fuzz timeouts should be fixed (https://github.com/bitcoin/bitcoin/issues/31066, #30498, …). However, this can also take time.

   So temporarily bump the fuzz timeout for now.

2. 
   DrahtBot commented at 9:18 pm on February 6, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31814.

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3. DrahtBot added the label Tests on Feb 6, 2025
4. ci: Bump fuzz task timeout faca7ac132
5. maflcko force-pushed on Feb 6, 2025
6. 
   dergoegge commented at 9:31 am on February 7, 2025: member

   ACK faca7ac13215fd88b420feea8f06d7404f8fd067
7. maflcko added this to the milestone 29.0 on Feb 7, 2025
8. fanquake merged this on Feb 7, 2025
9. fanquake closed this on Feb 7, 2025

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10. maflcko deleted the branch on Feb 7, 2025
11. 
    0xB10C commented at 11:48 am on February 7, 2025: contributor

    fwiw: duration of the fuzzer,address,undefined,integer, no depends task over the last few months in MM:SS
12. 
    maflcko commented at 12:28 pm on February 7, 2025: member

    Interesting. For context, the “speedup” after Jan 12 is likely due to fuzz input invalidation after commit 37af8bfb34d685bfd5d9a9ba6b35b4705e021535. And the “slowdown” after Dec 13th is likely due to adding fuzz inputs after commit https://github.com/bitcoin-core/qa-assets/commit/5c026e2a97b5f447a863734fb1c2566c33738d01.
13. 
    dergoegge commented at 1:30 pm on February 7, 2025: member

    Something we could also do is stop using libfuzzer’s coverage instrumentation in that task, as it makes things slower too. We aren’t using instrumentation in the other fuzz jobs either.

    We could still compile with libfuzzer but disable the instrumentation with -fsanitize-coverage-allowlist=allowlist.txt where the allow list is empty (i think).

    Not sure how much impact it has compared to the other sanitizers.

Contributors
maflcko DrahtBot dergoegge 0xB10C

Labels
Tests

Milestone
29.0