tvl-depot/third_party/git/t/perf/p5303-many-packs.sh
Vincent Ambo f4609b896f merge(3p/git): Merge git subtree at v2.29.2
This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb
2020-11-21 19:45:56 +01:00

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#!/bin/sh
test_description='performance with large numbers of packs'
. ./perf-lib.sh
test_perf_large_repo
# A real many-pack situation would probably come from having a lot of pushes
# over time. We don't know how big each push would be, but we can fake it by
# just walking the first-parent chain and having every 5 commits be their own
# "push". This isn't _entirely_ accurate, as real pushes would have some
# duplicate objects due to thin-pack fixing, but it's a reasonable
# approximation.
#
# And then all of the rest of the objects can go in a single packfile that
# represents the state before any of those pushes (actually, we'll generate
# that first because in such a setup it would be the oldest pack, and we sort
# the packs by reverse mtime inside git).
repack_into_n () {
rm -rf staging &&
mkdir staging &&
git rev-list --first-parent HEAD |
sed -n '1~5p' |
head -n "$1" |
perl -e 'print reverse <>' \
>pushes
# create base packfile
head -n 1 pushes |
git pack-objects --delta-base-offset --revs staging/pack
# and then incrementals between each pair of commits
last= &&
while read rev
do
if test -n "$last"; then
{
echo "$rev" &&
echo "^$last"
} |
git pack-objects --delta-base-offset --revs \
staging/pack || return 1
fi
last=$rev
done <pushes &&
# and install the whole thing
rm -f .git/objects/pack/* &&
mv staging/* .git/objects/pack/
}
# Pretend we just have a single branch and no reflogs, and that everything is
# in objects/pack; that makes our fake pack-building via repack_into_n()
# much simpler.
test_expect_success 'simplify reachability' '
tip=$(git rev-parse --verify HEAD) &&
git for-each-ref --format="option no-deref%0adelete %(refname)" |
git update-ref --stdin &&
rm -rf .git/logs &&
git update-ref refs/heads/master $tip &&
git symbolic-ref HEAD refs/heads/master &&
git repack -ad
'
for nr_packs in 1 50 1000
do
test_expect_success "create $nr_packs-pack scenario" '
repack_into_n $nr_packs
'
test_perf "rev-list ($nr_packs)" '
git rev-list --objects --all >/dev/null
'
test_perf "abbrev-commit ($nr_packs)" '
git rev-list --abbrev-commit HEAD >/dev/null
'
# This simulates the interesting part of the repack, which is the
# actual pack generation, without smudging the on-disk setup
# between trials.
test_perf "repack ($nr_packs)" '
GIT_TEST_FULL_IN_PACK_ARRAY=1 \
git pack-objects --keep-true-parents \
--honor-pack-keep --non-empty --all \
--reflog --indexed-objects --delta-base-offset \
--stdout </dev/null >/dev/null
'
done
# Measure pack loading with 10,000 packs.
test_expect_success 'generate lots of packs' '
for i in $(test_seq 10000); do
echo "blob"
echo "data <<EOF"
echo "blob $i"
echo "EOF"
echo "checkpoint"
done |
git -c fastimport.unpackLimit=0 fast-import
'
# The purpose of this test is to evaluate load time for a large number
# of packs while doing as little other work as possible.
test_perf "load 10,000 packs" '
git rev-parse --verify "HEAD^{commit}"
'
test_done