Mercurial > hg
view tests/test-journal.t @ 29830:92ac2baaea86
revlog: use an LRU cache for delta chain bases
Profiling using statprof revealed a hotspot during changegroup
application calculating delta chain bases on generaldelta repos.
Essentially, revlog._addrevision() was performing a lot of redundant
work tracing the delta chain as part of determining when the chain
distance was acceptable. This was most pronounced when adding
revisions to manifests, which can have delta chains thousands of
revisions long.
There was a delta chain base cache on revlogs before, but it only
captured a single revision. This was acceptable before generaldelta,
when _addrevision would build deltas from the previous revision and
thus we'd pretty much guarantee a cache hit when resolving the delta
chain base on a subsequent _addrevision call. However, it isn't
suitable for generaldelta because parent revisions aren't necessarily
the last processed revision.
This patch converts the delta chain base cache to an LRU dict cache.
The cache can hold multiple entries, so generaldelta repos have a
higher chance of getting a cache hit.
The impact of this change when processing changegroup additions is
significant. On a generaldelta conversion of the "mozilla-unified"
repo (which contains heads of the main Firefox repositories in
chronological order - this means there are lots of transitions between
heads in revlog order), this change has the following impact when
performing an `hg unbundle` of an uncompressed bundle of the repo:
before: 5:42 CPU time
after: 4:34 CPU time
Most of this time is saved when applying the changelog and manifest
revlogs:
before: 2:30 CPU time
after: 1:17 CPU time
That nearly a 50% reduction in CPU time applying changesets and
manifests!
Applying a gzipped bundle of the same repo (effectively simulating a
`hg clone` over HTTP) showed a similar speedup:
before: 5:53 CPU time
after: 4:46 CPU time
Wall time improvements were basically the same as CPU time.
I didn't measure explicitly, but it feels like most of the time
is saved when processing manifests. This makes sense, as large
manifests tend to have very long delta chains and thus benefit the
most from this cache.
So, this change effectively makes changegroup application (which is
used by `hg unbundle`, `hg clone`, `hg pull`, `hg unshelve`, and
various other commands) significantly faster when delta chains are
long (which can happen on repos with large numbers of files and thus
large manifests).
In theory, this change can result in more memory utilization. However,
we're caching a dict of ints. At most we have 200 ints + Python object
overhead per revlog. And, the cache is really only populated when
performing read-heavy operations, such as adding changegroups or
scanning an individual revlog. For memory bloat to be an issue, we'd
need to scan/read several revisions from several revlogs all while
having active references to several revlogs. I don't think there are
many operations that do this, so I don't think memory bloat from the
cache will be an issue.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Mon, 22 Aug 2016 21:48:50 -0700 |
parents | e54bdd3aa23b |
children | 6d11ae3c4c4b |
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Tests for the journal extension; records bookmark locations. $ cat >> testmocks.py << EOF > # mock out util.getuser() and util.makedate() to supply testable values > import os > from mercurial import util > def mockgetuser(): > return 'foobar' > > def mockmakedate(): > filename = os.path.join(os.environ['TESTTMP'], 'testtime') > try: > with open(filename, 'rb') as timef: > time = float(timef.read()) + 1 > except IOError: > time = 0.0 > with open(filename, 'wb') as timef: > timef.write(str(time)) > return (time, 0) > > util.getuser = mockgetuser > util.makedate = mockmakedate > EOF $ cat >> $HGRCPATH << EOF > [extensions] > journal= > testmocks=`pwd`/testmocks.py > EOF Setup repo $ hg init repo $ cd repo Test empty journal $ hg journal previous locations of '.': no recorded locations $ hg journal foo previous locations of 'foo': no recorded locations Test that working copy changes are tracked $ echo a > a $ hg commit -Aqm a $ hg journal previous locations of '.': cb9a9f314b8b commit -Aqm a $ echo b > a $ hg commit -Aqm b $ hg journal previous locations of '.': 1e6c11564562 commit -Aqm b cb9a9f314b8b commit -Aqm a $ hg up 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg journal previous locations of '.': cb9a9f314b8b up 0 1e6c11564562 commit -Aqm b cb9a9f314b8b commit -Aqm a Test that bookmarks are tracked $ hg book -r tip bar $ hg journal bar previous locations of 'bar': 1e6c11564562 book -r tip bar $ hg book -f bar $ hg journal bar previous locations of 'bar': cb9a9f314b8b book -f bar 1e6c11564562 book -r tip bar $ hg up 1 files updated, 0 files merged, 0 files removed, 0 files unresolved updating bookmark bar $ hg journal bar previous locations of 'bar': 1e6c11564562 up cb9a9f314b8b book -f bar 1e6c11564562 book -r tip bar Test that bookmarks and working copy tracking is not mixed $ hg journal previous locations of '.': 1e6c11564562 up cb9a9f314b8b up 0 1e6c11564562 commit -Aqm b cb9a9f314b8b commit -Aqm a Test that you can list all entries as well as limit the list or filter on them $ hg book -r tip baz $ hg journal --all previous locations of the working copy and bookmarks: 1e6c11564562 baz book -r tip baz 1e6c11564562 bar up 1e6c11564562 . up cb9a9f314b8b bar book -f bar 1e6c11564562 bar book -r tip bar cb9a9f314b8b . up 0 1e6c11564562 . commit -Aqm b cb9a9f314b8b . commit -Aqm a $ hg journal --limit 2 previous locations of '.': 1e6c11564562 up cb9a9f314b8b up 0 $ hg journal bar previous locations of 'bar': 1e6c11564562 up cb9a9f314b8b book -f bar 1e6c11564562 book -r tip bar $ hg journal foo previous locations of 'foo': no recorded locations $ hg journal . previous locations of '.': 1e6c11564562 up cb9a9f314b8b up 0 1e6c11564562 commit -Aqm b cb9a9f314b8b commit -Aqm a $ hg journal "re:ba." previous locations of 're:ba.': 1e6c11564562 baz book -r tip baz 1e6c11564562 bar up cb9a9f314b8b bar book -f bar 1e6c11564562 bar book -r tip bar Test that verbose, JSON, template and commit output work $ hg journal --verbose --all previous locations of the working copy and bookmarks: 000000000000 -> 1e6c11564562 foobar baz 1970-01-01 00:00 +0000 book -r tip baz cb9a9f314b8b -> 1e6c11564562 foobar bar 1970-01-01 00:00 +0000 up cb9a9f314b8b -> 1e6c11564562 foobar . 1970-01-01 00:00 +0000 up 1e6c11564562 -> cb9a9f314b8b foobar bar 1970-01-01 00:00 +0000 book -f bar 000000000000 -> 1e6c11564562 foobar bar 1970-01-01 00:00 +0000 book -r tip bar 1e6c11564562 -> cb9a9f314b8b foobar . 1970-01-01 00:00 +0000 up 0 cb9a9f314b8b -> 1e6c11564562 foobar . 1970-01-01 00:00 +0000 commit -Aqm b 000000000000 -> cb9a9f314b8b foobar . 1970-01-01 00:00 +0000 commit -Aqm a $ hg journal --verbose -Tjson [ { "command": "up", "date": [5.0, 0], "name": ".", "newhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"], "oldhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"], "user": "foobar" }, { "command": "up 0", "date": [2.0, 0], "name": ".", "newhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"], "oldhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"], "user": "foobar" }, { "command": "commit -Aqm b", "date": [1.0, 0], "name": ".", "newhashes": ["1e6c11564562b4ed919baca798bc4338bd299d6a"], "oldhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"], "user": "foobar" }, { "command": "commit -Aqm a", "date": [0.0, 0], "name": ".", "newhashes": ["cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b"], "oldhashes": ["0000000000000000000000000000000000000000"], "user": "foobar" } ] $ cat <<EOF >> $HGRCPATH > [templates] > j = "{oldhashes % '{node|upper}'} -> {newhashes % '{node|upper}'} > - user: {user} > - command: {command} > - date: {date|rfc3339date} > - newhashes: {newhashes} > - oldhashes: {oldhashes} > " > EOF $ hg journal -Tj -l1 previous locations of '.': CB9A9F314B8B07BA71012FCDBC544B5A4D82FF5B -> 1E6C11564562B4ED919BACA798BC4338BD299D6A - user: foobar - command: up - date: 1970-01-01T00:00:05+00:00 - newhashes: 1e6c11564562b4ed919baca798bc4338bd299d6a - oldhashes: cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b $ hg journal --commit previous locations of '.': 1e6c11564562 up changeset: 1:1e6c11564562 bookmark: bar bookmark: baz tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b cb9a9f314b8b up 0 changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a 1e6c11564562 commit -Aqm b changeset: 1:1e6c11564562 bookmark: bar bookmark: baz tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b cb9a9f314b8b commit -Aqm a changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a Test for behaviour on unexpected storage version information $ printf '42\0' > .hg/journal $ hg journal previous locations of '.': abort: unknown journal file version '42' [255] $ hg book -r tip doomed unsupported journal file version '42'