fncache: avoid loading the filename cache when not actually modifying it
With time, fncache can become very large. The mozilla-central repo for example,
has a 31M and growing fncache file. Loading this file takes time (280ms for the
mozilla-central repository).
In many scenarios, we don't need to load fncache at all. For example, when
committing changes to existing files, or pushing such commits to another clone.
This patch detects when a name is added via store.vfs(), and only loads the
cache if a) the data metadata file doesn't already exist, or b) when opening
for appending, the data or metadata file exists but has size (a transaction
rollback leaves behind such files).
Benchmarks (run on Macos 10.13 on a 2017-model Macbook Pro with Core i7 2.9GHz
and flash drive), each test without and with patch run 5 times:
* committing to an existing file, against the mozilla-central repository.
Baseline real time average 2.3736, with patch 1.9884.
* unbundling a large changeset consisting *only* of existing-file modifications
(159 revisions, 1050 modifications, mozilla-central
4a250a0e4f29:beea9ac7d823), into a clone limited to the ancestor revision of
that revset). Baseline real time average 1.5048, with patch 1.3108.
#!/usr/bin/env python
#
# hgperf - measure performance of Mercurial commands
#
# Copyright 2014 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''measure performance of Mercurial commands
Using ``hgperf`` instead of ``hg`` measures performance of the target
Mercurial command. For example, the execution below measures
performance of :hg:`heads --topo`::
$ hgperf heads --topo
All command output via ``ui`` is suppressed, and just measurement
result is displayed: see also "perf" extension in "contrib".
Costs of processing before dispatching to the command function like
below are not measured::
- parsing command line (e.g. option validity check)
- reading configuration files in
But ``pre-`` and ``post-`` hook invocation for the target command is
measured, even though these are invoked before or after dispatching to
the command function, because these may be required to repeat
execution of the target command correctly.
'''
import os
import sys
libdir = '@LIBDIR@'
if libdir != '@' 'LIBDIR' '@':
if not os.path.isabs(libdir):
libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)),
libdir)
libdir = os.path.abspath(libdir)
sys.path.insert(0, libdir)
# enable importing on demand to reduce startup time
try:
from mercurial import demandimport; demandimport.enable()
except ImportError:
import sys
sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
' '.join(sys.path))
sys.stderr.write("(check your install and PYTHONPATH)\n")
sys.exit(-1)
from mercurial import (
dispatch,
util,
)
def timer(func, title=None):
results = []
begin = util.timer()
count = 0
while True:
ostart = os.times()
cstart = util.timer()
r = func()
cstop = util.timer()
ostop = os.times()
count += 1
a, b = ostart, ostop
results.append((cstop - cstart, b[0] - a[0], b[1]-a[1]))
if cstop - begin > 3 and count >= 100:
break
if cstop - begin > 10 and count >= 3:
break
if title:
sys.stderr.write("! %s\n" % title)
if r:
sys.stderr.write("! result: %s\n" % r)
m = min(results)
sys.stderr.write("! wall %f comb %f user %f sys %f (best of %d)\n"
% (m[0], m[1] + m[2], m[1], m[2], count))
orgruncommand = dispatch.runcommand
def runcommand(lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions):
ui.pushbuffer()
lui.pushbuffer()
timer(lambda : orgruncommand(lui, repo, cmd, fullargs, ui,
options, d, cmdpats, cmdoptions))
ui.popbuffer()
lui.popbuffer()
dispatch.runcommand = runcommand
dispatch.run()