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merge: mark file gets as not thread safe (issue5933)...
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

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python3-ratchet.py
115 lines | 4.2 KiB | text/x-python | PythonLexer
# Copyright 2012 Facebook
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Find tests that newly pass under Python 3.
The approach is simple: we maintain a whitelist of Python 3 passing
tests in the repository, and periodically run all the /other/ tests
and look for new passes. Any newly passing tests get automatically
added to the whitelist.
You probably want to run it like this:
$ cd tests
$ python3 ../contrib/python3-ratchet.py \
> --working-tests=../contrib/python3-whitelist
"""
from __future__ import print_function
from __future__ import absolute_import
import argparse
import json
import os
import subprocess
import sys
_hgenv = dict(os.environ)
_hgenv.update({
'HGPLAIN': '1',
})
_HG_FIRST_CHANGE = '9117c6561b0bd7792fa13b50d28239d51b78e51f'
def _runhg(*args):
return subprocess.check_output(args, env=_hgenv)
def _is_hg_repo(path):
return _runhg('hg', 'log', '-R', path,
'-r0', '--template={node}').strip() == _HG_FIRST_CHANGE
def _py3default():
if sys.version_info[0] >= 3:
return sys.executable
return 'python3'
def main(argv=()):
p = argparse.ArgumentParser()
p.add_argument('--working-tests',
help='List of tests that already work in Python 3.')
p.add_argument('--commit-to-repo',
help='If set, commit newly fixed tests to the given repo')
p.add_argument('-j', default=os.sysconf(r'SC_NPROCESSORS_ONLN'), type=int,
help='Number of parallel tests to run.')
p.add_argument('--python3', default=_py3default(),
help='python3 interpreter to use for test run')
p.add_argument('--commit-user',
default='python3-ratchet@mercurial-scm.org',
help='Username to specify when committing to a repo.')
opts = p.parse_args(argv)
if opts.commit_to_repo:
if not _is_hg_repo(opts.commit_to_repo):
print('abort: specified repository is not the hg repository')
sys.exit(1)
if not opts.working_tests or not os.path.isfile(opts.working_tests):
print('abort: --working-tests must exist and be a file (got %r)' %
opts.working_tests)
sys.exit(1)
elif opts.commit_to_repo:
root = _runhg('hg', 'root').strip()
if not opts.working_tests.startswith(root):
print('abort: if --commit-to-repo is given, '
'--working-tests must be from that repo')
sys.exit(1)
try:
subprocess.check_call([opts.python3, '-c',
'import sys ; '
'assert ((3, 5) <= sys.version_info < (3, 6) '
'or sys.version_info >= (3, 6, 2))'])
except subprocess.CalledProcessError:
print('warning: Python 3.6.0 and 3.6.1 have '
'a bug which breaks Mercurial')
print('(see https://bugs.python.org/issue29714 for details)')
sys.exit(1)
rt = subprocess.Popen([opts.python3, 'run-tests.py', '-j', str(opts.j),
'--blacklist', opts.working_tests, '--json'])
rt.wait()
with open('report.json') as f:
data = f.read()
report = json.loads(data.split('=', 1)[1])
newpass = set()
for test, result in report.items():
if result['result'] != 'success':
continue
# A new passing test! Huzzah!
newpass.add(test)
if newpass:
# We already validated the repo, so we can just dive right in
# and commit.
if opts.commit_to_repo:
print(len(newpass), 'new passing tests on Python 3!')
with open(opts.working_tests) as f:
oldpass = {l for l in f.read().splitlines() if l}
with open(opts.working_tests, 'w') as f:
for p in sorted(oldpass | newpass):
f.write('%s\n' % p)
_runhg('hg', 'commit', '-R', opts.commit_to_repo,
'--user', opts.commit_user,
'--message', 'python3: expand list of passing tests')
else:
print('Newly passing tests:', '\n'.join(sorted(newpass)))
sys.exit(2)
if __name__ == '__main__':
main(sys.argv[1:])