Mercurial > hg
view tests/test-issue1175.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 | 62c8f7691bc3 |
children | 76b69cccb07a 5b7175377bab |
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http://mercurial.selenic.com/bts/issue1175 $ hg init $ touch a $ hg ci -Am0 adding a $ hg mv a a1 $ hg ci -m1 $ hg co 0 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg mv a a2 $ hg up note: possible conflict - a was renamed multiple times to: a2 a1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg ci -m2 $ touch a $ hg ci -Am3 adding a $ hg mv a b $ hg ci -Am4 a $ hg ci --debug --traceback -Am5 b b b: searching for copy revision for a b: copy a:b80de5d138758541c5f05265ad144ab9fa86d1db committed changeset 5:89e8e4be0de296fa3d6dd7825ccc44d7dc0f1f3b $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 6 changesets, 4 total revisions $ hg export --git tip # HG changeset patch # User test # Date 0 0 # Node ID 89e8e4be0de296fa3d6dd7825ccc44d7dc0f1f3b # Parent 7fc86ba705e717a721dbc361bf8c9bc05a18ca2f 5 diff --git a/b b/b new file mode 100644