Delete nonreduced fuzz inputs #221

1. 
   maflcko commented at 5:05 pm on March 25, 2025: contributor

   As per the usual process to avoid wasted CI resources and timeouts when CI runs on large and presumed irrelevant inputs.

   Normally, deletion of non-reduced fuzz inputs should happen after feature-freeze on the master Bitcoin Core branch, but before branch-off, so that the latest release branch retains mostly valid fuzz inputs.

   Previous: #204

   To “reproduce”

   Install a fresh VM, as explained in the bash script’s doc, and run it:

   0apt update && apt install curl -y
   1curl -L -O https://raw.githubusercontent.com/bitcoin-core/bitcoin-maintainer-tools/main/delete_nonreduced_fuzz_inputs.sh
   2bash delete_nonreduced_fuzz_inputs.sh
   

   To “test”

   • Keep an eye on coverage stats, to ensure it doesn’t drop
   • Re-run the script, to ensure it is “reproducible” to some extent
   • Anything else you think is important to test or review

   CI

   CI should pass, except for a lint failure, which should light up on any changes like this pull request, which delete fuzz inputs.

2. Delete fuzz inputs 20e827ca2f
3. Reduced inputs for afl-cmin e3b4a1493c
4. Reduced inputs for fuzzer 518a3d8283
5. Reduced inputs for fuzzer,address,undefined,integer 2b825cd506
6. 
   maflcko commented at 5:12 pm on March 25, 2025: contributor

   Storage device usage (du -sh ./fuzz_corpora/)

   5.8G -> 2.7G

   Determinism

   • ~125k fuzz input files deleted

   0git diff --stat origin/main..2b825cd506de7403c69ecf3e8a6f495b8dc1dcad | tail -1
   1 125400 files changed
   

   • Cross-diff with a second run of the script: 4k fuzz input files

   0git -c diff.renameLimit=2007 diff --stat HEAD..2b825cd506de7403c69ecf3e8a6f495b8dc1dcad | tail -1 
   1 3737 files changed
   

   Coverage

   • main: https://drahtbot.space/host_reports/DrahtBot/reports/coverage_fuzz/monotree/dfb7d58108daf372/c62dc520e0c7caee/fuzz.coverage/index.html
   • pull: https://drahtbot.space/host_reports/DrahtBot/reports/coverage_fuzz/monotree/dfb7d58108daf372/2b825cd506de7403/fuzz.coverage/index.html
7. 
   maflcko commented at 6:57 pm on March 25, 2025: contributor

   The coverage run completed, but it looks like the coverage decreases in some lines. Not sure if this happened in the past.

   For example, Assert(expect_work) is no longer hit, when comparing https://drahtbot.space/host_reports/DrahtBot/reports/coverage_fuzz/monotree/dfb7d58108daf372/c62dc520e0c7caee/fuzz.coverage/src/test/fuzz/txdownloadman.cpp.gcov.html and https://drahtbot.space/host_reports/DrahtBot/reports/coverage_fuzz/monotree/dfb7d58108daf372/2b825cd506de7403/fuzz.coverage/src/test/fuzz/txdownloadman.cpp.gcov.html

   Not sure why this would happen, other than due to https://github.com/bitcoin/bitcoin/issues/29018

8. 
   maflcko commented at 7:02 pm on March 25, 2025: contributor

   Though, the cross-diff is at a historic low, so the result is one of the most deterministic ones (so far)
9. 
   maflcko commented at 8:51 am on March 26, 2025: contributor

   This is ready for review, now that CI passed, except for the expected ’lint’ failure.
10. 
    marcofleon commented at 5:39 pm on March 26, 2025: contributor

    Reviewing this now. About how long is the script expected to take?
11. 
    maflcko commented at 7:12 am on March 27, 2025: contributor

    Looking at the commit timestamps, it took around 4 hours, but it could be more or less, depending on your compute, memory and storage.
12. 
    marcofleon commented at 3:12 pm on March 27, 2025: contributor

    Original: https://marcofleon.github.io/coverage/original_fuzz_corpora/ Reduced: https://marcofleon.github.io/coverage/reduced_fuzz_corpora/

    Both coverage reports generated on the most commit in master. Looks generally good to me, there was a little drop in function coverage (e.g. chain.cpp, hash.cpp, rpc/server.cpp) but must just be some instability.

    Corpora went from 5.7G to 2.7G.

13. dergoegge merged this on Mar 27, 2025
14. dergoegge closed this on Mar 27, 2025

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Contributors
maflcko marcofleon