On Thu, Sep 06 2018, Ævar Arnfjörð Bjarmason wrote:
> On Thu, Sep 06 2018, SZEDER Gábor wrote: > >> On Thu, Sep 06, 2018 at 02:26:49PM +0200, Ævar Arnfjörð Bjarmason wrote: >>> >>> On Thu, Sep 06 2018, SZEDER Gábor wrote: >>> > Several tests failed occasionally when the test suite was run with >>> > 'GIT_TEST_SPLIT_INDEX=yes'. Here are those that I managed to trace >>> > back to this racy split index problem, starting with those failing >>> > more frequently, with a link to a failing Travis CI build job for >>> > each. The highlighted line shows when the racy file was written, >>> > which is not always in the failing test (but note that those lines are >>> > in the 'after failure' fold, and your browser might unhelpfully fold >>> > it up before you could take a good look). >>> >>> Thanks for working on this. When I package up git I run the tests >>> under a few different modes, in the case of split index I've been >>> doing: >>> >>> GIT_TEST_SPLIT_INDEX=true GIT_SKIP_TESTS="t3903 t4015.77" >> >> Yeah, I noticed that you mentioned this in an unrelated thread the >> other day, that's why I put you on Cc. ... and that's why I pulled >> this series from the backburner and cleaned it up for submission. >> (Gah, most of these commits have an author date back in February...) >> >>> Since those were the ones I spotted failing under that mode, but >>> I still had occasional other failures, I don't have a record of >>> which, maybe some of these other tests you mention, maybe not. >> >> I poked around the Travis CI API, and managed to get the logs of all >> build jobs that failed with 'GIT_TEST_SPLIT_INDEX=yes' but succeeded >> without it. Here is the list of failed test scripts, along with how >> many times they failed: >> >> 1 t0027-auto-crlf.sh >> 1 t0090-cache-tree.sh >> 1 t3404-rebase-interactive.sh >> 1 t5520-pull.sh >> 1 t5573-pull-verify-signatures.sh >> 1 t5608-clone-2gb.sh >> 1 t7406-submodule-update.sh >> 2 t2200-add-update.sh >> 2 t4002-diff-basic.sh >> 2 t5504-fetch-receive-strict.sh >> 3 t0028-working-tree-encoding.sh >> 4 t1000-read-tree-m-3way.sh >> 6 t4015-diff-whitespace.sh >> 10 t4024-diff-optimize-common.sh >> 17 t3030-merge-recursive.sh >> 17 t3402-rebase-merge.sh >> 17 t3501-revert-cherry-pick.sh >> 17 t6022-merge-rename.sh >> 17 t6032-merge-large-rename.sh >> 17 t6034-merge-rename-nocruft.sh >> 17 t6042-merge-rename-corner-cases.sh >> 17 t6043-merge-rename-directories.sh >> 17 t6046-merge-skip-unneeded-updates.sh >> 17 t7003-filter-branch.sh >> 17 t7601-merge-pull-config.sh >> 23 t3903-stash.sh >> >> I doubt that this racy split index problem is responsible for all >> these failures; e.g. I looked at the failures of a few merge-related >> test scripts, and these logs show that they tend to fail because of >> memory corruption, i.e. with 'Aborted (core dumped)' or 'Segmentation >> fault (core dumped)'. >> >>> To test how this this series improves things, I've been running >>> this on a 56 core CentOS 7.5 machine: >>> >>> while true; do GIT_TEST_SPLIT_INDEX=yes prove -j$(parallel >>> --number-of-cores) t3903-stash.sh t4024-diff-optimize-common.sh >>> t4015-diff-whitespace.sh t2200-add-update.sh t0090-cache-tree.sh && echo >>> "OK $(date) $(git describe)" >>log2 || echo "FAIL $(date) $(git describe)" >>> >>log2; done >>> >>> While, in another window to get some load on the machine (these seem to >>> fail more under load): >>> >>> while true; do prove -j$(parallel --number-of-cores) t[156789]*.sh; done >>> >>> The results with this series applied up to 4/5. I.e. without the actual >>> fix: >>> >>> 92 OK v2.19.0-rc2-6-ged839bd155 >>> 8 FAIL v2.19.0-rc2-6-ged839bd155 >>> >>> I.e. when running this 100 times, I got 8 failures. So 8%. >> >> Lucky you ;) >> >> I could only get t3903 to fail on me, but not the others. That was >> enough to eventually track down and fix the problem (fun! ;), and then >> I looked at the logs of failed git/git Travis CI build jobs to see, >> what other failures might have been caused by it. >> >>> With this patch applied: >>> >>> 389 OK v2.19.0-rc2-5-g05a5a13935 >>> 11 FAIL v2.19.0-rc2-5-g05a5a13935 >>> >>> This time I ran the tests 400 times, and got 11 failures, i.e. a >>> ~2.8% failure rate. I don't have a full account of what stuff >>> failed (this was just scrolling past in my terminal), but most >>> were: >>> >>> t0090-cache-tree.sh (Wstat: 256 Tests: 21 Failed: 3) >>> Failed tests: 10-12 >>> Non-zero exit status: 1 >>> >>> I.e. these tests: >>> >>> ok 10 - commit --interactive gives cache-tree on partial commit >>> ok 11 - commit in child dir has cache-tree >>> ok 12 - reset --hard gives cache-tree >> >> But hey, 't0090 --verbose-log -x -i' just failed on me with the fix >> applied while writing this email, yay! In its logs I see the >> following errors in all three tests you mention: >> >> error: index uses ?½þA extension, which we do not understand >> fatal: index file corrupt >> >> Test 13 then starts with 'rm -f .git/index', and then all is well for >> the remaining tests. >> >> There was a recent discussion about a similar error starting at: >> >> https://public-inbox.org/git/20180901214157.hxlqmbz3fds7hsdl@ltop.local/ >> >> and leading to a fix in 6c003d6ffb (reopen_tempfile(): truncate opened >> file, 2018-09-04). I certainly hope that not my fix is buggy, but >> combined with 'GIT_TEST_SPLIT_INDEX=yes' it can occasionally trigger >> the same error, and Peff's (Cc'd) fix will resolve it as well. >> >> Could you run your stress tests with Peff's fix merged with mine? >> Apparetly your setup is much more capable of triggering these issues >> than mine... > > I get the same sort of thing on t0090-cache-tree.sh with -v -x, > i.e. failures due to: > > error: index uses �)�? extension, which we do not understand > fatal: index file corrupt > > It turns out that my inability to reproduce that earlier was because I'd > forgotten to set GIT_TEST_SPLIT_INDEX=yes in the environment for that > while loop, so I wasn't testing the split index at all. > > I'm now running the tests in a lop with 6c003d6ffb cherry-picked on > top. I'll report back when I have enough data to say if/how it helped. I got 436 OK runs with that and 3 failures before I gave up and ctrl+c'd it. And the 3 failures were: t3903-stash.sh (Wstat: 256 Tests: 90 Failed: 1) Failed test: 55 Non-zero exit status: 1 So it's back to failing on the same test as before your patches. I did try merging in "pu" to get git-stash in C. There I had 2 failures and 135 OK before I gave up. The C version failed tests 5 & 20, so there may be some new regressions in the C version related to this.
