t/perf/p5303-many-packs.sh

   1 #!/bin/sh
   2
   3 test_description='performance with large numbers of packs'
   4 . ./perf-lib.sh
   5
   6 test_perf_large_repo
   7
   8 # A real many-pack situation would probably come from having a lot of pushes
   9 # over time. We don't know how big each push would be, but we can fake it by
  10 # just walking the first-parent chain and having every 5 commits be their own
  11 # "push". This isn't _entirely_ accurate, as real pushes would have some
  12 # duplicate objects due to thin-pack fixing, but it's a reasonable
  13 # approximation.
  14 #
  15 # And then all of the rest of the objects can go in a single packfile that
  16 # represents the state before any of those pushes (actually, we'll generate
  17 # that first because in such a setup it would be the oldest pack, and we sort
  18 # the packs by reverse mtime inside git).
  19 repack_into_n () {
  20         rm -rf staging &&
  21         mkdir staging &&
  22
  23         git rev-list --first-parent HEAD |
  24         sed -n '1~5p' |
  25         head -n "$1" |
  26         perl -e 'print reverse <>' \
  27         >pushes
  28
  29         # create base packfile
  30         head -n 1 pushes |
  31         git pack-objects --delta-base-offset --revs staging/pack
  32
  33         # and then incrementals between each pair of commits
  34         last= &&
  35         while read rev
  36         do
  37                 if test -n "$last"; then
  38                         {
  39                                 echo "$rev" &&
  40                                 echo "^$last"
  41                         } |
  42                         git pack-objects --delta-base-offset --revs \
  43                                 staging/pack || return 1
  44                 fi
  45                 last=$rev
  46         done <pushes &&
  47
  48         # and install the whole thing
  49         rm -f .git/objects/pack/* &&
  50         mv staging/* .git/objects/pack/
  51 }
  52
  53 # Pretend we just have a single branch and no reflogs, and that everything is
  54 # in objects/pack; that makes our fake pack-building via repack_into_n()
  55 # much simpler.
  56 test_expect_success 'simplify reachability' '
  57         tip=$(git rev-parse --verify HEAD) &&
  58         git for-each-ref --format="option no-deref%0adelete %(refname)" |
  59         git update-ref --stdin &&
  60         rm -rf .git/logs &&
  61         git update-ref refs/heads/master $tip &&
  62         git symbolic-ref HEAD refs/heads/master &&
  63         git repack -ad
  64 '
  65
  66 for nr_packs in 1 50 1000
  67 do
  68         test_expect_success "create $nr_packs-pack scenario" '
  69                 repack_into_n $nr_packs
  70         '
  71
  72         test_perf "rev-list ($nr_packs)" '
  73                 git rev-list --objects --all >/dev/null
  74         '
  75
  76         # This simulates the interesting part of the repack, which is the
  77         # actual pack generation, without smudging the on-disk setup
  78         # between trials.
  79         test_perf "repack ($nr_packs)" '
  80                 git pack-objects --keep-true-parents \
  81                   --honor-pack-keep --non-empty --all \
  82                   --reflog --indexed-objects --delta-base-offset \
  83                   --stdout </dev/null >/dev/null
  84         '
  85 done
  86
  87 test_done