Mercurial > hg
view tests/test-rust-ancestor.py @ 51681:522b4d729e89
mmap: populate the mapping by default
Without pre-population, accessing all data through a mmap can result in many
pagefault, reducing performance significantly. If the mmap is prepopulated, the
performance can no longer get slower than a full read.
(See benchmark number below)
In some cases were very few data is read, prepopulating can be overkill and
slower than populating on access (through page fault). So that behavior can be
controlled when the caller can pre-determine the best behavior.
(See benchmark number below)
In addition, testing with populating in a secondary thread yield great result
combining the best of each approach. This might be implemented in later
changesets.
In all cases, using mmap has a great effect on memory usage when many processes
run in parallel on the same machine.
### Benchmarks
# What did I run
A couple of month back I ran a large benchmark campaign to assess the impact of
various approach for using mmap with the revlog (and other files), it
highlighted a few benchmarks that capture the impact of the changes well. So to
validate this change I checked the following:
- log command displaying various revisions
(read the changelog index)
- log command displaying the patch of listed revisions
(read the changelog index, the manifest index and a few files indexes)
- unbundling a few revisions
(read and write changelog, manifest and few files indexes, and walk the graph
to update some cache)
- pushing a few revisions
(read and write changelog, manifest and few files indexes, walk the graph to
update some cache, performs various accesses locally and remotely during
discovery)
Benchmarks were run using the default module policy (c+py) and the rust one. No
significant difference were found between the two implementation, so we will
present result using the default policy (unless otherwise specified).
I ran them on a few repositories :
- mercurial: a "public changeset only" copy of mercurial from 2018-08-01 using
zstd compression and sparse-revlog
- pypy: a copy of pypy from 2018-08-01 using zstd compression and sparse-revlog
- netbeans: a copy of netbeans from 2018-08-01 using zstd compression and
sparse-revlog
- mozilla-try: a copy of mozilla-try from 2019-02-18 using zstd compression and
sparse-revlog
- mozilla-try persistent-nodemap: Same as the above but with a persistent
nodemap. Used for the log --patch benchmark only
# Results
For the smaller repositories (mercurial, pypy), the impact of mmap is almost
imperceptible, other cost dominating the operation. The impact of prepopulating
is undiscernible in the benchmark we ran.
For larger repositories the benchmark support explanation given above:
On netbeans, the log can be about 1% faster without repopulation (for a
difference < 100ms) but unbundle becomes a bit slower, even when small.
### data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog
# benchmark.name = hg.command.unbundle
# benchmark.variants.issue6528 = disabled
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
# benchmark.variants.source = unbundle
# benchmark.variants.verbosity = quiet
with-populate: 0.240157
no-populate: 0.265087 (+10.38%, +0.02)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.459518
no-populate: 1.481290 (+1.49%, +0.02)
## benchmark.name = hg.command.push
# benchmark.variants.explicit-rev = none
# benchmark.variants.issue6528 = disabled
# benchmark.variants.protocol = ssh
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
with-populate: 0.771919
no-populate: 0.792025 (+2.60%, +0.02)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.459518
no-populate: 1.481290 (+1.49%, +0.02)
For mozilla-try, the "slow down" from pre-populate for small `hg log` is more
visible, but still small in absolute time. (using rust value for the persistent
nodemap value to be relevant).
### data-env-vars.name = mozilla-try-2019-02-18-ds2-pnm
# benchmark.name = hg.command.log
# bin-env-vars.hg.flavor = rust
# benchmark.variants.patch = yes
# benchmark.variants.limit-rev = 1
with-populate: 0.237813
no-populate: 0.229452 (-3.52%, -0.01)
# benchmark.variants.limit-rev = 10
# benchmark.variants.patch = yes
with-populate: 1.213578
no-populate: 1.205189
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.variants.limit-rev = 1000
# benchmark.variants.patch = no
# benchmark.variants.rev = tip
with-populate: 0.198607
no-populate: 0.195038 (-1.80%, -0.00)
However pre-populating provide a significant boost on more complex operations
like unbundle or push:
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.name = hg.command.push
# benchmark.variants.explicit-rev = none
# benchmark.variants.issue6528 = disabled
# benchmark.variants.protocol = ssh
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
with-populate: 4.798632
no-populate: 4.953295 (+3.22%, +0.15)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 4.903618
no-populate: 5.014963 (+2.27%, +0.11)
## benchmark.name = hg.command.unbundle
# benchmark.variants.revs = any-1-extra-rev
with-populate: 1.423411
no-populate: 1.585365 (+11.38%, +0.16)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.537909
no-populate: 1.688489 (+9.79%, +0.15)
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Thu, 11 Apr 2024 00:02:07 +0200 |
parents | 03fdd4d7b5bd |
children |
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import sys import unittest from mercurial.node import wdirrev from mercurial.testing import revlog as revlogtesting try: from mercurial import rustext rustext.__name__ # trigger immediate actual import except ImportError: rustext = None else: # this would fail already without appropriate ancestor.__package__ from mercurial.rustext.ancestor import ( AncestorsIterator, LazyAncestors, MissingAncestors, ) from mercurial.rustext import dagop try: from mercurial.cext import parsers as cparsers except ImportError: cparsers = None @unittest.skipIf( rustext is None, 'The Rust version of the "ancestor" module is not available. It is needed' ' for this test.', ) @unittest.skipIf( rustext is None, 'The Rust or C version of the "parsers" module, which the "ancestor" module' ' relies on, is not available.', ) class rustancestorstest(revlogtesting.RustRevlogBasedTestBase): """Test the correctness of binding to Rust code. This test is merely for the binding to Rust itself: extraction of Python variable, giving back the results etc. It is not meant to test the algorithmic correctness of the operations on ancestors it provides. Hence the very simple embedded index data is good enough. Algorithmic correctness is asserted by the Rust unit tests. """ def testiteratorrevlist(self): idx = self.parserustindex() # checking test assumption about the index binary data: self.assertEqual( {i: (r[5], r[6]) for i, r in enumerate(idx)}, {0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)}, ) ait = AncestorsIterator(idx, [3], 0, True) self.assertEqual([r for r in ait], [3, 2, 1, 0]) ait = AncestorsIterator(idx, [3], 0, False) self.assertEqual([r for r in ait], [2, 1, 0]) def testlazyancestors(self): idx = self.parserustindex() start_count = sys.getrefcount(idx) # should be 2 (see Python doc) self.assertEqual( {i: (r[5], r[6]) for i, r in enumerate(idx)}, {0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)}, ) lazy = LazyAncestors(idx, [3], 0, True) # we have two more references to the index: # - in its inner iterator for __contains__ and __bool__ # - in the LazyAncestors instance itself (to spawn new iterators) self.assertEqual(sys.getrefcount(idx), start_count + 2) self.assertTrue(2 in lazy) self.assertTrue(bool(lazy)) self.assertEqual(list(lazy), [3, 2, 1, 0]) # a second time to validate that we spawn new iterators self.assertEqual(list(lazy), [3, 2, 1, 0]) # now let's watch the refcounts closer ait = iter(lazy) self.assertEqual(sys.getrefcount(idx), start_count + 3) del ait self.assertEqual(sys.getrefcount(idx), start_count + 2) del lazy self.assertEqual(sys.getrefcount(idx), start_count) # let's check bool for an empty one self.assertFalse(LazyAncestors(idx, [0], 0, False)) def testmissingancestors(self): idx = self.parserustindex() missanc = MissingAncestors(idx, [1]) self.assertTrue(missanc.hasbases()) self.assertEqual(missanc.missingancestors([3]), [2, 3]) missanc.addbases({2}) self.assertEqual(missanc.bases(), {1, 2}) self.assertEqual(missanc.missingancestors([3]), [3]) self.assertEqual(missanc.basesheads(), {2}) def testmissingancestorsremove(self): idx = self.parserustindex() missanc = MissingAncestors(idx, [1]) revs = {0, 1, 2, 3} missanc.removeancestorsfrom(revs) self.assertEqual(revs, {2, 3}) def testrefcount(self): idx = self.parserustindex() start_count = sys.getrefcount(idx) # refcount increases upon iterator init... ait = AncestorsIterator(idx, [3], 0, True) self.assertEqual(sys.getrefcount(idx), start_count + 1) self.assertEqual(next(ait), 3) # and decreases once the iterator is removed del ait self.assertEqual(sys.getrefcount(idx), start_count) # and removing ref to the index after iterator init is no issue ait = AncestorsIterator(idx, [3], 0, True) del idx self.assertEqual(list(ait), [3, 2, 1, 0]) # the index is not tracked by the GC, hence there is nothing more # we can assert to check that it is properly deleted once its refcount # drops to 0 def testgrapherror(self): data = ( revlogtesting.data_non_inlined[: 64 + 27] + b'\xf2' + revlogtesting.data_non_inlined[64 + 28 :] ) idx = self.parserustindex(data=data) with self.assertRaises(rustext.GraphError) as arc: AncestorsIterator(idx, [1], -1, False) exc = arc.exception self.assertIsInstance(exc, ValueError) # rust-cpython issues appropriate str instances for Python 2 and 3 self.assertEqual(exc.args, ('ParentOutOfRange', 1)) def testwdirunsupported(self): # trying to access ancestors of the working directory raises idx = self.parserustindex() with self.assertRaises(rustext.GraphError) as arc: list(AncestorsIterator(idx, [wdirrev], -1, False)) exc = arc.exception self.assertIsInstance(exc, ValueError) # rust-cpython issues appropriate str instances for Python 2 and 3 self.assertEqual(exc.args, ('InvalidRevision', wdirrev)) def testheadrevs(self): idx = self.parserustindex() self.assertEqual(dagop.headrevs(idx, [1, 2, 3]), {3}) if __name__ == '__main__': import silenttestrunner silenttestrunner.main(__name__)