Mercurial > hg
view tests/test-bad-extension.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 | fcb517ff9562 |
children | d58958676b3c |
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ensure that failing ui.atexit handlers report sensibly $ cat > $TESTTMP/bailatexit.py <<EOF > from mercurial import util > def bail(): > raise RuntimeError('ui.atexit handler exception') > > def extsetup(ui): > ui.atexit(bail) > EOF $ hg -q --config extensions.bailatexit=$TESTTMP/bailatexit.py \ > help help hg help [-ecks] [TOPIC] show help for a given topic or a help overview error in exit handlers: Traceback (most recent call last): File "*/mercurial/dispatch.py", line *, in _runexithandlers (glob) func(*args, **kwargs) File "$TESTTMP/bailatexit.py", line *, in bail (glob) raise RuntimeError('ui.atexit handler exception') RuntimeError: ui.atexit handler exception [255] $ rm $TESTTMP/bailatexit.py another bad extension $ echo 'raise Exception("bit bucket overflow")' > badext.py $ abspathexc=`pwd`/badext.py $ cat >baddocext.py <<EOF > """ > baddocext is bad > """ > EOF $ abspathdoc=`pwd`/baddocext.py $ cat <<EOF >> $HGRCPATH > [extensions] > gpg = > hgext.gpg = > badext = $abspathexc > baddocext = $abspathdoc > badext2 = > EOF $ hg -q help help 2>&1 |grep extension *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow *** failed to import extension badext2: No module named badext2 show traceback $ hg -q help help --traceback 2>&1 | egrep ' extension|^Exception|Traceback|ImportError' *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow Traceback (most recent call last): Exception: bit bucket overflow *** failed to import extension badext2: No module named badext2 Traceback (most recent call last): ImportError: No module named badext2 names of extensions failed to load can be accessed via extensions.notloaded() $ cat <<EOF > showbadexts.py > from mercurial import commands, extensions, registrar > cmdtable = {} > command = registrar.command(cmdtable) > @command(b'showbadexts', norepo=True) > def showbadexts(ui, *pats, **opts): > ui.write('BADEXTS: %s\n' % ' '.join(sorted(extensions.notloaded()))) > EOF $ hg --config extensions.badexts=showbadexts.py showbadexts 2>&1 | grep '^BADEXTS' BADEXTS: badext badext2 show traceback for ImportError of hgext.name if devel.debug.extensions is set $ (hg help help --traceback --debug --config devel.debug.extensions=yes 2>&1) \ > | grep -v '^ ' \ > | egrep 'extension..[^p]|^Exception|Traceback|ImportError|not import' *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow Traceback (most recent call last): Exception: bit bucket overflow could not import hgext.badext2 (No module named *badext2): trying hgext3rd.badext2 (glob) Traceback (most recent call last): ImportError: No module named *badext2 (glob) could not import hgext3rd.badext2 (No module named *badext2): trying badext2 (glob) Traceback (most recent call last): ImportError: No module named *badext2 (glob) *** failed to import extension badext2: No module named badext2 Traceback (most recent call last): ImportError: No module named badext2 confirm that there's no crash when an extension's documentation is bad $ hg help --keyword baddocext *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow *** failed to import extension badext2: No module named badext2 Topics: extensions Using Additional Features