Mercurial > hg
view tests/test-relink.t @ 16120:47ee41fcf42b
largefiles: optimize update speed by only updating changed largefiles
Historically, during 'hg update', every largefile in the working copy was
hashed (which is a very expensive operation on big files) and any
largefiles that did not have a hash that matched their standin were
updated.
This patch optimizes 'hg update' by keeping track of what standins have
changed between the old and new revisions, and only updating the largefiles
that have changed. This saves a lot of time by avoiding the unecessary
calculation of a list of sha1 hashes for big files.
With this patch, the time 'hg update' takes to complete is a function of
how many largefiles need to be updated and what their size is.
Performance tests on a repository with about 80 largefiles ranging from
a few MB to about 97 MB are shown below. The tests show how long it takes
to run 'hg update' with no changes actually being updated.
Mercurial 2.1 release:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
getting changed largefiles
0 largefiles updated, 0 removed
real 0m10.045s
user 0m9.367s
sys 0m0.674s
With this patch:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
real 0m0.965s
user 0m0.845s
sys 0m0.115s
The same repsoitory, without the largefiles extension enabled:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
real 0m0.799s
user 0m0.684s
sys 0m0.111s
So before the patch, 'hg update' with no changes was approximately 9.25s
slower with largefiles enabled. With this patch, it is approximately 0.165s
slower.
author | Na'Tosha Bard <natosha@unity3d.com> |
---|---|
date | Mon, 13 Feb 2012 18:37:07 +0100 |
parents | 9910f60a37ee |
children | 4f795f5fbb0b |
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$ echo "[extensions]" >> $HGRCPATH $ echo "relink=" >> $HGRCPATH $ fix_path() { > tr '\\' / > } $ cat > arelinked.py <<EOF > import sys, os > from mercurial import util > path1, path2 = sys.argv[1:3] > if util.samefile(path1, path2): > print '%s == %s' % (path1, path2) > else: > print '%s != %s' % (path1, path2) > EOF create source repository $ hg init repo $ cd repo $ echo a > a $ echo b > b $ hg ci -Am addfile adding a adding b $ cat $TESTDIR/binfile.bin >> a $ cat $TESTDIR/binfile.bin >> b $ hg ci -Am changefiles make another commit to create files larger than 1 KB to test formatting of final byte count $ cat $TESTDIR/binfile.bin >> a $ cat $TESTDIR/binfile.bin >> b $ hg ci -m anotherchange don't sit forever trying to double-lock the source repo $ hg relink . relinking $TESTTMP/repo/.hg/store to $TESTTMP/repo/.hg/store (glob) there is nothing to relink Test files are read in binary mode $ python -c "file('.hg/store/data/dummy.i', 'wb').write('a\r\nb\n')" $ cd .. clone and pull to break links $ hg clone --pull -r0 repo clone adding changesets adding manifests adding file changes added 1 changesets with 2 changes to 2 files updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd clone $ hg pull -q $ echo b >> b $ hg ci -m changeb created new head $ python -c "file('.hg/store/data/dummy.i', 'wb').write('a\nb\r\n')" relink $ hg relink --debug | fix_path relinking $TESTTMP/repo/.hg/store to $TESTTMP/clone/.hg/store tip has 2 files, estimated total number of files: 3 collecting: 00changelog.i 1/3 files (33.33%) collecting: 00manifest.i 2/3 files (66.67%) collecting: a.i 3/3 files (100.00%) collecting: b.i 4/3 files (133.33%) collecting: dummy.i 5/3 files (166.67%) collected 5 candidate storage files not linkable: 00changelog.i not linkable: 00manifest.i pruning: data/a.i 3/5 files (60.00%) not linkable: data/b.i pruning: data/dummy.i 5/5 files (100.00%) pruned down to 2 probably relinkable files relinking: data/a.i 1/2 files (50.00%) not linkable: data/dummy.i relinked 1 files (1.37 KB reclaimed) $ cd .. check hardlinks $ python arelinked.py repo/.hg/store/data/a.i clone/.hg/store/data/a.i repo/.hg/store/data/a.i == clone/.hg/store/data/a.i $ python arelinked.py repo/.hg/store/data/b.i clone/.hg/store/data/b.i repo/.hg/store/data/b.i != clone/.hg/store/data/b.i