Subject: Re: [External] Re: [PATCH v1] commit-graph.c: no lazy fetch in lookup_commit_in_graph()

From: Patrick Steinhardt <[email-masked]>
Date: Mon, 20 Jun 2022 11:05:29 +0200

On Mon, Jun 20, 2022 at 04:53:47PM +0800, 欣韩 wrote:
> On Mon, Jun 20, 2022 at 3:34 PM Patrick Steinhardt <[email-masked]> wrote:
> >
> > On Sat, Jun 18, 2022 at 11:01:30AM +0800, Han Xin wrote:
[snip]
> > > +test_expect_success 'prepare a repository with a commit-graph contains commit two' '
> > > +     git init source &&
> > > +     echo "$(pwd)/dest.git/objects" >source/.git/objects/info/alternates &&
> > > +     git -C source remote add origin "$(pwd)/dest.git" &&
> > > +     git -C source config remote.origin.promisor true &&
> > > +     git -C source config remote.origin.partialclonefilter blob:none &&
> > > +     # the source repository has the whole refs contains refs/heads/tmp
> > > +     git -C source fetch origin &&
> > > +     (
> > > +             cd source &&
> > > +             test_commit three &&
> > > +             git -c gc.writeCommitGraph=true gc
> > > +     )
> > > +'
> > > +
> > > +test_expect_success 'change the alternates of source to that without commit two' '
> > > +     # now we have a commit-graph in the source repository but without the commit two
> > > +     echo "$(pwd)/alternates/objects" >source/.git/objects/info/alternates
> > > +'
> > > +
> > > +test_expect_success 'fetch the missing commit' '
> > > +     git -C source fetch origin $oid 2>fetch.out &&
> > > +     grep "$oid" fetch.out
> > > +'
> >
> > This test passes even without your fix, albeit a lot slower compared
> > to with it. Can we somehow cause it to fail reliably so that the test
> > becomes effective in catching a regression here?
> >
> 
> Could you help me find the reason why this testcase passes even
> without the fix.
> 
> From the execution of Github Action, it seems that the problem always exist：
> https://github.com/chiyutianyi/git/actions/runs/2527421443.
> 
> Thanks.
> -Han Xin

Hard to say, I'm not sure either. One thing I noticed though is that in
your CI run there's failure in e.g. linux-gcc, but the test run for
linux-musl succeeds. Personally I'm using musl libc on my system, as
well, so maybe it's a discrepancy between musl- and glibc-based systems?

Patrick