On 10/9/2020 11:29 AM, Thomas Braun wrote: > I think I have a starting point for what goes wrong. I found a local > repo with another broken commit graph. And after some fiddling the > following script can reproduce it. I tried with git/git first but that > seems not to trigger that. I'm glad you're able to trigger bad commit-graph data somehow. Let's see what's going on: > # rm -rf dummy > mkdir dummy > cd dummy > > git init > > git remote add origin https://github.com/tango-controls/cppTango > git remote add fork1 https://github.com/bourtemb/cppTango > git remote add fork2 https://github.com/t-b/cppTango > git fetch --all --jobs 12 My gut reaction is that this parallel fetching is causing an issue, but we will see. Do you get a repro if you drop the "--jobs 12"? > git commit-graph verify > rm -rf .git/objects/info/commit-graphs/ > git commit-graph verify > git fetch --jobs 12 > git remote add fork3 git@xxxxxxxxxx:t-b/cppTango.git > git commit-graph verify > git remote add fork4 git@xxxxxxxxxx:t-b/cppTango.git > git fetch --jobs 12 > git commit-graph verify > > The last verify outputs > > commit-graph generation for commit > 029341567c24582030592585b395f4438273263f is 1054 != 1 > commit-graph generation for commit > 1e8d10aec7ca6075f622c447d416071390698124 is 4294967295 != 1171 > commit-graph generation for commit > 296e93516189c0134843fd56ac4f10d36ccf284f is 1054 != 1 > commit-graph generation for commit > 4c0a7a3cd369d06b99d867be6b47a96c519efd7f is 1054 != 1 > commit-graph has non-zero generation number for commit > 4d39849950d3dc02b7426c780ac7991ec7221176, but zero elsewhere > commit-graph has non-zero generation number for commit 4 > [....] This looks more troubling than just duplicate rows, but perhaps those duplicate rows are causing sufficient confusion when reading the commit-graph during the 'verify' command? I tried incorporating this into the Git test suite so I could test it on v2.29.0-rc0 and the current merge-check, but I'm failing to reproduce the failure with this script: diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh index c334ee9155..2b3f3db593 100755 --- a/t/t5324-split-commit-graph.sh +++ b/t/t5324-split-commit-graph.sh @@ -440,4 +440,26 @@ test_expect_success '--split=replace with partial Bloom data' ' verify_chain_files_exist $graphdir ' +test_expect_success 'test' ' + git init dummy && + ( + cd dummy && + export GIT_TRACE2_EVENT="$TRASH_DIRECTORY/../trace.txt" && + git config fetch.writeCommitGraph true && + git remote add origin https://github.com/tango-controls/cppTango && + git remote add fork1 https://github.com/bourtemb/cppTango && + git remote add fork2 https://github.com/t-b/cppTango && + git fetch --all --jobs 12 && + git commit-graph verify && + rm -rf .git/objects/info/commit-graphs/ && + git commit-graph verify && + git fetch --jobs 12 && + git remote add fork3 git@xxxxxxxxxx:t-b/cppTango.git && + git commit-graph verify && + git remote add fork4 git@xxxxxxxxxx:t-b/cppTango.git && + git fetch --jobs 12 && + git commit-graph verify + ) +' + test_done I tried this on Linux and Windows, and under "--stress" but never saw a failure. Thomas: some things that could possibly help is if you repro this situation but also do something like export GIT_TRACE2_EVENT="$(pwd)/trace.txt" so we can read the details of everything Git is tracing during these parallel jobs. We might be able to stitch together a sequence of events that lead to these failures. Thanks, Stolee
