Mercurial > hg
view tests/test-simplemerge.py @ 38732:be4984261611
merge: mark file gets as not thread safe (issue5933)
In default installs, this has the effect of disabling the thread-based
worker on Windows when manifesting files in the working directory. My
measurements have shown that with revlog-based repositories, Mercurial
spends a lot of CPU time in revlog code resolving file data. This ends
up incurring a lot of context switching across threads and slows down
`hg update` operations when going from an empty working directory to
the tip of the repo.
On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs):
before: 487s wall
after: 360s wall (equivalent to worker.enabled=false)
cpus=2: 379s wall
Even with only 2 threads, the thread pool is still slower.
The introduction of the thread-based worker (02b36e860e0b) states that
it resulted in a "~50%" speedup for `hg sparse --enable-profile` and
`hg sparse --disable-profile`. This disagrees with my measurement
above. I theorize a few reasons for this:
1) Removal of files from the working directory is I/O - not CPU - bound
and should benefit from a thread pool (unless I/O is insanely fast
and the GIL release is near instantaneous). So tests like `hg sparse
--enable-profile` may exercise deletion throughput and aren't good
benchmarks for worker tasks that are CPU heavy.
2) The patch was authored by someone at Facebook. The results were
likely measured against a repository using remotefilelog. And I
believe that revision retrieval during working directory updates with
remotefilelog will often use a remote store, thus being I/O and not
CPU bound. This probably resulted in an overstated performance gain.
Since there appears to be a need to enable the thread-based worker with
some stores, I've made the flagging of file gets as thread safe
configurable. I've made it experimental because I don't want to formalize
a boolean flag for this option and because this attribute is best
captured against the store implementation. But we don't have a proper
store API for this yet. I'd rather cross this bridge later.
It is possible there are revlog-based repositories that do benefit from
a thread-based worker. I didn't do very comprehensive testing. If there
are, we may want to devise a more proper algorithm for whether to use
the thread-based worker, including possibly config options to limit the
number of threads to use. But until I see evidence that justifies
complexity, simplicity wins.
Differential Revision: https://phab.mercurial-scm.org/D3963
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 18 Jul 2018 09:49:34 -0700 |
parents | 02850baddadd |
children | d75142ef054a |
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# Copyright (C) 2004, 2005 Canonical Ltd # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, see <http://www.gnu.org/licenses/>. from __future__ import absolute_import import unittest from mercurial import ( error, simplemerge, util, ) from mercurial.utils import ( stringutil, ) TestCase = unittest.TestCase # bzr compatible interface, for the tests class Merge3(simplemerge.Merge3Text): """3-way merge of texts. Given BASE, OTHER, THIS, tries to produce a combined text incorporating the changes from both BASE->OTHER and BASE->THIS. All three will typically be sequences of lines.""" def __init__(self, base, a, b): basetext = b'\n'.join([i.strip(b'\n') for i in base] + [b'']) atext = b'\n'.join([i.strip(b'\n') for i in a] + [b'']) btext = b'\n'.join([i.strip(b'\n') for i in b] + [b'']) if (stringutil.binary(basetext) or stringutil.binary(atext) or stringutil.binary(btext)): raise error.Abort(b"don't know how to merge binary files") simplemerge.Merge3Text.__init__(self, basetext, atext, btext, base, a, b) CantReprocessAndShowBase = simplemerge.CantReprocessAndShowBase def split_lines(t): return util.stringio(t).readlines() ############################################################ # test case data from the gnu diffutils manual # common base TZU = split_lines(b""" The Nameless is the origin of Heaven and Earth; The named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their outcome. The two are the same, But after they are produced, they have different names. They both may be called deep and profound. Deeper and more profound, The door of all subtleties! """) LAO = split_lines(b""" The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; The Named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their outcome. The two are the same, But after they are produced, they have different names. """) TAO = split_lines(b""" The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; The named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their result. The two are the same, But after they are produced, they have different names. -- The Way of Lao-Tzu, tr. Wing-tsit Chan """) MERGED_RESULT = split_lines(b"""\ The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; The Named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their result. The two are the same, But after they are produced, they have different names.\ \n<<<<<<< LAO\ \n======= -- The Way of Lao-Tzu, tr. Wing-tsit Chan \ \n>>>>>>> TAO """) class TestMerge3(TestCase): def log(self, msg): pass def test_no_changes(self): """No conflicts because nothing changed""" m3 = Merge3([b'aaa', b'bbb'], [b'aaa', b'bbb'], [b'aaa', b'bbb']) self.assertEqual(m3.find_unconflicted(), [(0, 2)]) self.assertEqual(list(m3.find_sync_regions()), [(0, 2, 0, 2, 0, 2), (2, 2, 2, 2, 2, 2)]) self.assertEqual(list(m3.merge_regions()), [(b'unchanged', 0, 2)]) self.assertEqual(list(m3.merge_groups()), [(b'unchanged', [b'aaa', b'bbb'])]) def test_front_insert(self): m3 = Merge3([b'zz'], [b'aaa', b'bbb', b'zz'], [b'zz']) # todo: should use a sentinel at end as from get_matching_blocks # to match without zz self.assertEqual(list(m3.find_sync_regions()), [(0, 1, 2, 3, 0, 1), (1, 1, 3, 3, 1, 1)]) self.assertEqual(list(m3.merge_regions()), [(b'a', 0, 2), (b'unchanged', 0, 1)]) self.assertEqual(list(m3.merge_groups()), [(b'a', [b'aaa', b'bbb']), (b'unchanged', [b'zz'])]) def test_null_insert(self): m3 = Merge3([], [b'aaa', b'bbb'], []) # todo: should use a sentinel at end as from get_matching_blocks # to match without zz self.assertEqual(list(m3.find_sync_regions()), [(0, 0, 2, 2, 0, 0)]) self.assertEqual(list(m3.merge_regions()), [(b'a', 0, 2)]) self.assertEqual(list(m3.merge_lines()), [b'aaa', b'bbb']) def test_no_conflicts(self): """No conflicts because only one side changed""" m3 = Merge3([b'aaa', b'bbb'], [b'aaa', b'111', b'bbb'], [b'aaa', b'bbb']) self.assertEqual(m3.find_unconflicted(), [(0, 1), (1, 2)]) self.assertEqual(list(m3.find_sync_regions()), [(0, 1, 0, 1, 0, 1), (1, 2, 2, 3, 1, 2), (2, 2, 3, 3, 2, 2)]) self.assertEqual(list(m3.merge_regions()), [(b'unchanged', 0, 1), (b'a', 1, 2), (b'unchanged', 1, 2)]) def test_append_a(self): m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'bbb\n', b'222\n'], [b'aaa\n', b'bbb\n']) self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n') def test_append_b(self): m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'bbb\n'], [b'aaa\n', b'bbb\n', b'222\n']) self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n') def test_append_agreement(self): m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'bbb\n', b'222\n'], [b'aaa\n', b'bbb\n', b'222\n']) self.assertEqual(b''.join(m3.merge_lines()), b'aaa\nbbb\n222\n') def test_append_clash(self): m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'bbb\n', b'222\n'], [b'aaa\n', b'bbb\n', b'333\n']) ml = m3.merge_lines(name_a=b'a', name_b=b'b', start_marker=b'<<', mid_marker=b'--', end_marker=b'>>') self.assertEqual(b''.join(ml), b'aaa\n' b'bbb\n' b'<< a\n' b'222\n' b'--\n' b'333\n' b'>> b\n' ) def test_insert_agreement(self): m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'222\n', b'bbb\n'], [b'aaa\n', b'222\n', b'bbb\n']) ml = m3.merge_lines(name_a=b'a', name_b=b'b', start_marker=b'<<', mid_marker=b'--', end_marker=b'>>') self.assertEqual(b''.join(ml), b'aaa\n222\nbbb\n') def test_insert_clash(self): """Both try to insert lines in the same place.""" m3 = Merge3([b'aaa\n', b'bbb\n'], [b'aaa\n', b'111\n', b'bbb\n'], [b'aaa\n', b'222\n', b'bbb\n']) self.assertEqual(m3.find_unconflicted(), [(0, 1), (1, 2)]) self.assertEqual(list(m3.find_sync_regions()), [(0, 1, 0, 1, 0, 1), (1, 2, 2, 3, 2, 3), (2, 2, 3, 3, 3, 3)]) self.assertEqual(list(m3.merge_regions()), [(b'unchanged', 0, 1), (b'conflict', 1, 1, 1, 2, 1, 2), (b'unchanged', 1, 2)]) self.assertEqual(list(m3.merge_groups()), [(b'unchanged', [b'aaa\n']), (b'conflict', [], [b'111\n'], [b'222\n']), (b'unchanged', [b'bbb\n']), ]) ml = m3.merge_lines(name_a=b'a', name_b=b'b', start_marker=b'<<', mid_marker=b'--', end_marker=b'>>') self.assertEqual(b''.join(ml), b'''aaa << a 111 -- 222 >> b bbb ''') def test_replace_clash(self): """Both try to insert lines in the same place.""" m3 = Merge3([b'aaa', b'000', b'bbb'], [b'aaa', b'111', b'bbb'], [b'aaa', b'222', b'bbb']) self.assertEqual(m3.find_unconflicted(), [(0, 1), (2, 3)]) self.assertEqual(list(m3.find_sync_regions()), [(0, 1, 0, 1, 0, 1), (2, 3, 2, 3, 2, 3), (3, 3, 3, 3, 3, 3)]) def test_replace_multi(self): """Replacement with regions of different size.""" m3 = Merge3([b'aaa', b'000', b'000', b'bbb'], [b'aaa', b'111', b'111', b'111', b'bbb'], [b'aaa', b'222', b'222', b'222', b'222', b'bbb']) self.assertEqual(m3.find_unconflicted(), [(0, 1), (3, 4)]) self.assertEqual(list(m3.find_sync_regions()), [(0, 1, 0, 1, 0, 1), (3, 4, 4, 5, 5, 6), (4, 4, 5, 5, 6, 6)]) def test_merge_poem(self): """Test case from diff3 manual""" m3 = Merge3(TZU, LAO, TAO) ml = list(m3.merge_lines(b'LAO', b'TAO')) self.log(b'merge result:') self.log(b''.join(ml)) self.assertEqual(ml, MERGED_RESULT) def test_binary(self): with self.assertRaises(error.Abort): Merge3([b'\x00'], [b'a'], [b'b']) def test_dos_text(self): base_text = b'a\r\n' this_text = b'b\r\n' other_text = b'c\r\n' m3 = Merge3(base_text.splitlines(True), other_text.splitlines(True), this_text.splitlines(True)) m_lines = m3.merge_lines(b'OTHER', b'THIS') self.assertEqual(b'<<<<<<< OTHER\r\nc\r\n=======\r\nb\r\n' b'>>>>>>> THIS\r\n'.splitlines(True), list(m_lines)) def test_mac_text(self): base_text = b'a\r' this_text = b'b\r' other_text = b'c\r' m3 = Merge3(base_text.splitlines(True), other_text.splitlines(True), this_text.splitlines(True)) m_lines = m3.merge_lines(b'OTHER', b'THIS') self.assertEqual(b'<<<<<<< OTHER\rc\r=======\rb\r' b'>>>>>>> THIS\r'.splitlines(True), list(m_lines)) if __name__ == '__main__': # hide the timer import time orig = time.time try: time.time = lambda: 0 unittest.main() finally: time.time = orig