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view mercurial/lsprof.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 | d4e5b2653693 |
children | b25fbe7e494e |
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from __future__ import absolute_import, print_function import _lsprof import sys Profiler = _lsprof.Profiler # PyPy doesn't expose profiler_entry from the module. profiler_entry = getattr(_lsprof, 'profiler_entry', None) __all__ = ['profile', 'Stats'] def profile(f, *args, **kwds): """XXX docstring""" p = Profiler() p.enable(subcalls=True, builtins=True) try: f(*args, **kwds) finally: p.disable() return Stats(p.getstats()) class Stats(object): """XXX docstring""" def __init__(self, data): self.data = data def sort(self, crit=r"inlinetime"): """XXX docstring""" # profiler_entries isn't defined when running under PyPy. if profiler_entry: if crit not in profiler_entry.__dict__: raise ValueError("Can't sort by %s" % crit) elif self.data and not getattr(self.data[0], crit, None): raise ValueError("Can't sort by %s" % crit) self.data.sort(key=lambda x: getattr(x, crit), reverse=True) for e in self.data: if e.calls: e.calls.sort(key=lambda x: getattr(x, crit), reverse=True) def pprint(self, top=None, file=None, limit=None, climit=None): """XXX docstring""" if file is None: file = sys.stdout d = self.data if top is not None: d = d[:top] cols = "% 12s %12s %11.4f %11.4f %s\n" hcols = "% 12s %12s %12s %12s %s\n" file.write(hcols % ("CallCount", "Recursive", "Total(s)", "Inline(s)", "module:lineno(function)")) count = 0 for e in d: file.write(cols % (e.callcount, e.reccallcount, e.totaltime, e.inlinetime, label(e.code))) count += 1 if limit is not None and count == limit: return ccount = 0 if climit and e.calls: for se in e.calls: file.write(cols % (se.callcount, se.reccallcount, se.totaltime, se.inlinetime, " %s" % label(se.code))) count += 1 ccount += 1 if limit is not None and count == limit: return if climit is not None and ccount == climit: break def freeze(self): """Replace all references to code objects with string descriptions; this makes it possible to pickle the instance.""" # this code is probably rather ickier than it needs to be! for i in range(len(self.data)): e = self.data[i] if not isinstance(e.code, str): self.data[i] = type(e)((label(e.code),) + e[1:]) if e.calls: for j in range(len(e.calls)): se = e.calls[j] if not isinstance(se.code, str): e.calls[j] = type(se)((label(se.code),) + se[1:]) _fn2mod = {} def label(code): if isinstance(code, str): return code try: mname = _fn2mod[code.co_filename] except KeyError: for k, v in list(sys.modules.iteritems()): if v is None: continue if not isinstance(getattr(v, '__file__', None), str): continue if v.__file__.startswith(code.co_filename): mname = _fn2mod[code.co_filename] = k break else: mname = _fn2mod[code.co_filename] = '<%s>' % code.co_filename return '%s:%d(%s)' % (mname, code.co_firstlineno, code.co_name) if __name__ == '__main__': import os sys.argv = sys.argv[1:] if not sys.argv: print("usage: lsprof.py <script> <arguments...>", file=sys.stderr) sys.exit(2) sys.path.insert(0, os.path.abspath(os.path.dirname(sys.argv[0]))) stats = profile(execfile, sys.argv[0], globals(), locals()) stats.sort() stats.pprint()