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view tests/test-context-metadata.t @ 44363:f7459da77f23
nodemap: introduce an option to use mmap to read the nodemap mapping
The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.
This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).
Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:
Before:
* do not use the persistent nodemap
* use the CPython implementation of the index for nodemap
* use mmapping of the changelog index
After:
* use the MixedIndex Rust code, with the NodeTree object for nodemap access
(still in review)
* use the persistent nodemap data from disk
* access the persistent nodemap data through mmap
* use mmapping of the changelog index
The persistent nodemap greatly speed up most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.
Here are some numbers (in seconds) for the reference copy of mozilla-try:
Revset Before After abs-change speedup
-10000: 0.004622 0.005532 0.000910 × 0.83
-10: 0.000050 0.000132 0.000082 × 0.37
tip 0.000052 0.000085 0.000033 × 0.61
0 + (-10000:) 0.028222 0.005337 -0.022885 × 5.29
0 0.023521 0.000084 -0.023437 × 280.01
(-10000:) + 0 0.235539 0.005308 -0.230231 × 44.37
(-10:) + :9 0.232883 0.000180 -0.232703 ×1293.79
(-10000:) + (:99) 0.238735 0.005358 -0.233377 × 44.55
:99 + (-10000:) 0.317942 0.005593 -0.312349 × 56.84
:9 + (-10:) 0.313372 0.000179 -0.313193 ×1750.68
:9 0.316450 0.000143 -0.316307 ×2212.93
On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.
Here are some numbers (in seconds) for the reference copy of mercurial:
Revset Before After abs-change speedup
-10: 0.000065 0.000097 0.000032 × 0.67
tip 0.000063 0.000078 0.000015 × 0.80
0 0.000561 0.000079 -0.000482 × 7.10
-10000: 0.004609 0.003648 -0.000961 × 1.26
0 + (-10000:) 0.005023 0.003715 -0.001307 × 1.35
(-10:) + :9 0.002187 0.000108 -0.002079 ×20.25
(-10000:) + 0 0.006252 0.003716 -0.002536 × 1.68
(-10000:) + (:99) 0.006367 0.003707 -0.002660 × 1.71
:9 + (-10:) 0.003846 0.000110 -0.003736 ×34.96
:9 0.003854 0.000099 -0.003755 ×38.92
:99 + (-10000:) 0.007644 0.003778 -0.003866 × 2.02
Differential Revision: https://phab.mercurial-scm.org/D7894
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Tue, 11 Feb 2020 11:18:52 +0100 |
parents | b8db53f786f0 |
children | 42d2b31cee0b |
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Tests about metadataonlyctx $ hg init $ echo A > A $ hg commit -A A -m 'Add A' $ echo B > B $ hg commit -A B -m 'Add B' $ hg rm A $ echo C > C $ echo B2 > B $ hg add C -q $ hg commit -m 'Remove A' $ cat > metaedit.py <<EOF > from __future__ import absolute_import > from mercurial import context, pycompat, registrar > cmdtable = {} > command = registrar.command(cmdtable) > @command(b'metaedit') > def metaedit(ui, repo, arg): > # Modify commit message to "FOO" > with repo.wlock(), repo.lock(), repo.transaction(b'metaedit'): > old = repo[b'.'] > kwargs = dict(s.split(b'=', 1) for s in arg.split(b';')) > if b'parents' in kwargs: > kwargs[b'parents'] = map(int, kwargs[b'parents'].split(b',')) > new = context.metadataonlyctx(repo, old, > **pycompat.strkwargs(kwargs)) > new.commit() > EOF $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'text=Changed' $ hg log -r tip changeset: 3:ad83e9e00ec9 tag: tip parent: 1:3afb7afe6632 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Changed $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'parents=0' 2>&1 | egrep '^RuntimeError' RuntimeError: can't reuse the manifest: its p1 doesn't match the new ctx p1 $ hg --config extensions.metaedit=$TESTTMP/metaedit.py metaedit 'user=foo <foo@example.com>' $ hg log -r tip changeset: 4:1f86eaeca92b tag: tip parent: 1:3afb7afe6632 user: foo <foo@example.com> date: Thu Jan 01 00:00:00 1970 +0000 summary: Remove A