Mercurial > hg
view tests/test-extensions-afterloaded.t @ 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 | d1a49a94c324 |
children | cfa564037789 |
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Test the extensions.afterloaded() function $ cat > foo.py <<EOF > from mercurial import extensions > def uisetup(ui): > ui.write(b"foo.uisetup\\n") > ui.flush() > def bar_loaded(loaded): > ui.write(b"foo: bar loaded: %r\\n" % (loaded,)) > ui.flush() > extensions.afterloaded(b'bar', bar_loaded) > EOF $ cat > bar.py <<EOF > def uisetup(ui): > ui.write(b"bar.uisetup\\n") > ui.flush() > EOF $ basepath=`pwd` $ hg init basic $ cd basic $ echo foo > file $ hg add file $ hg commit -m 'add file' $ echo '[extensions]' >> .hg/hgrc $ echo "foo = $basepath/foo.py" >> .hg/hgrc $ echo "bar = $basepath/bar.py" >> .hg/hgrc $ hg log -r. -T'{rev}\n' foo.uisetup foo: bar loaded: True bar.uisetup 0 Test afterloaded with the opposite extension load order $ cd .. $ hg init basic_reverse $ cd basic_reverse $ echo foo > file $ hg add file $ hg commit -m 'add file' $ echo '[extensions]' >> .hg/hgrc $ echo "bar = $basepath/bar.py" >> .hg/hgrc $ echo "foo = $basepath/foo.py" >> .hg/hgrc $ hg log -r. -T'{rev}\n' bar.uisetup foo.uisetup foo: bar loaded: True 0 Test the extensions.afterloaded() function when the requested extension is not loaded $ cd .. $ hg init notloaded $ cd notloaded $ echo foo > file $ hg add file $ hg commit -m 'add file' $ echo '[extensions]' >> .hg/hgrc $ echo "foo = $basepath/foo.py" >> .hg/hgrc $ hg log -r. -T'{rev}\n' foo.uisetup foo: bar loaded: False 0 Test the extensions.afterloaded() function when the requested extension is not configured but fails the minimum version check $ cd .. $ cat > minvers.py <<EOF > minimumhgversion = b'9999.9999' > def uisetup(ui): > ui.write(b"minvers.uisetup\\n") > ui.flush() > EOF $ hg init minversion $ cd minversion $ echo foo > file $ hg add file $ hg commit -m 'add file' $ echo '[extensions]' >> .hg/hgrc $ echo "foo = $basepath/foo.py" >> .hg/hgrc $ echo "bar = $basepath/minvers.py" >> .hg/hgrc $ hg log -r. -T'{rev}\n' (third party extension bar requires version 9999.9999 or newer of Mercurial; disabling) foo.uisetup foo: bar loaded: False 0 Test the extensions.afterloaded() function when the requested extension is not configured but fails the minimum version check, using the opposite load order for the two extensions. $ cd .. $ hg init minversion_reverse $ cd minversion_reverse $ echo foo > file $ hg add file $ hg commit -m 'add file' $ echo '[extensions]' >> .hg/hgrc $ echo "bar = $basepath/minvers.py" >> .hg/hgrc $ echo "foo = $basepath/foo.py" >> .hg/hgrc $ hg log -r. -T'{rev}\n' (third party extension bar requires version 9999.9999 or newer of Mercurial; disabling) foo.uisetup foo: bar loaded: False 0