Mercurial > hg
view tests/test-hardlinks.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 | b95a6fb7ae66 |
children | 0a57945aaf7f |
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#require hardlink reporevlogstore $ cat > nlinks.py <<EOF > from __future__ import print_function > import sys > from mercurial import util > for f in sorted(sys.stdin.readlines()): > f = f[:-1] > print(util.nlinks(f), f) > EOF $ nlinksdir() > { > find "$@" -type f | $PYTHON $TESTTMP/nlinks.py > } Some implementations of cp can't create hardlinks (replaces 'cp -al' on Linux): $ cat > linkcp.py <<EOF > from __future__ import absolute_import > import sys > from mercurial import util > util.copyfiles(sys.argv[1], sys.argv[2], hardlink=True) > EOF $ linkcp() > { > $PYTHON $TESTTMP/linkcp.py $1 $2 > } Prepare repo r1: $ hg init r1 $ cd r1 $ echo c1 > f1 $ hg add f1 $ hg ci -m0 $ mkdir d1 $ cd d1 $ echo c2 > f2 $ hg add f2 $ hg ci -m1 $ cd ../.. $ nlinksdir r1/.hg/store 1 r1/.hg/store/00changelog.i 1 r1/.hg/store/00manifest.i 1 r1/.hg/store/data/d1/f2.i 1 r1/.hg/store/data/f1.i 1 r1/.hg/store/fncache (repofncache !) 1 r1/.hg/store/phaseroots 1 r1/.hg/store/undo 1 r1/.hg/store/undo.backup.fncache (repofncache !) 1 r1/.hg/store/undo.backupfiles 1 r1/.hg/store/undo.phaseroots Create hardlinked clone r2: $ hg clone -U --debug r1 r2 --config progress.debug=true linking: 1 linking: 2 linking: 3 linking: 4 linking: 5 linking: 6 linking: 7 linked 7 files Create non-hardlinked clone r3: $ hg clone --pull r1 r3 requesting all changes adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 2 files new changesets 40d85e9847f2:7069c422939c updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved Repos r1 and r2 should now contain hardlinked files: $ nlinksdir r1/.hg/store 2 r1/.hg/store/00changelog.i 2 r1/.hg/store/00manifest.i 2 r1/.hg/store/data/d1/f2.i 2 r1/.hg/store/data/f1.i 2 r1/.hg/store/fncache (repofncache !) 1 r1/.hg/store/phaseroots 1 r1/.hg/store/undo 1 r1/.hg/store/undo.backup.fncache (repofncache !) 1 r1/.hg/store/undo.backupfiles 1 r1/.hg/store/undo.phaseroots $ nlinksdir r2/.hg/store 2 r2/.hg/store/00changelog.i 2 r2/.hg/store/00manifest.i 2 r2/.hg/store/data/d1/f2.i 2 r2/.hg/store/data/f1.i 2 r2/.hg/store/fncache (repofncache !) Repo r3 should not be hardlinked: $ nlinksdir r3/.hg/store 1 r3/.hg/store/00changelog.i 1 r3/.hg/store/00manifest.i 1 r3/.hg/store/data/d1/f2.i 1 r3/.hg/store/data/f1.i 1 r3/.hg/store/fncache (repofncache !) 1 r3/.hg/store/phaseroots 1 r3/.hg/store/undo 1 r3/.hg/store/undo.backupfiles 1 r3/.hg/store/undo.phaseroots Create a non-inlined filelog in r3: $ cd r3/d1 >>> f = open('data1', 'wb') >>> for x in range(10000): ... f.write(b"%d\n" % x) and None >>> f.close() $ for j in 0 1 2 3 4 5 6 7 8 9; do > cat data1 >> f2 > hg commit -m$j > done $ cd ../.. $ nlinksdir r3/.hg/store 1 r3/.hg/store/00changelog.i 1 r3/.hg/store/00manifest.i 1 r3/.hg/store/data/d1/f2.d 1 r3/.hg/store/data/d1/f2.i 1 r3/.hg/store/data/f1.i 1 r3/.hg/store/fncache (repofncache !) 1 r3/.hg/store/phaseroots 1 r3/.hg/store/undo 1 r3/.hg/store/undo.backup.fncache (repofncache !) 1 r3/.hg/store/undo.backup.phaseroots 1 r3/.hg/store/undo.backupfiles 1 r3/.hg/store/undo.phaseroots Push to repo r1 should break up most hardlinks in r2: $ hg -R r2 verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 2 changesets, 2 total revisions $ cd r3 $ hg push pushing to $TESTTMP/r1 searching for changes adding changesets adding manifests adding file changes added 10 changesets with 10 changes to 1 files $ cd .. $ nlinksdir r2/.hg/store 1 r2/.hg/store/00changelog.i 1 r2/.hg/store/00manifest.i 1 r2/.hg/store/data/d1/f2.i 2 r2/.hg/store/data/f1.i [12] r2/\.hg/store/fncache (re) (repofncache !) #if hardlink-whitelisted repofncache $ nlinksdir r2/.hg/store/fncache 2 r2/.hg/store/fncache #endif $ hg -R r2 verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 2 changesets, 2 total revisions $ cd r1 $ hg up 1 files updated, 0 files merged, 0 files removed, 0 files unresolved Committing a change to f1 in r1 must break up hardlink f1.i in r2: $ echo c1c1 >> f1 $ hg ci -m00 $ cd .. $ nlinksdir r2/.hg/store 1 r2/.hg/store/00changelog.i 1 r2/.hg/store/00manifest.i 1 r2/.hg/store/data/d1/f2.i 1 r2/.hg/store/data/f1.i [12] r2/\.hg/store/fncache (re) (repofncache !) #if hardlink-whitelisted repofncache $ nlinksdir r2/.hg/store/fncache 2 r2/.hg/store/fncache #endif Create a file which exec permissions we will change $ cd r3 $ echo "echo hello world" > f3 $ hg add f3 $ hg ci -mf3 $ cd .. $ cd r3 $ hg tip --template '{rev}:{node|short}\n' 12:d3b77733a28a $ echo bla > f1 $ chmod +x f3 $ hg ci -m1 $ cd .. Create hardlinked copy r4 of r3 (on Linux, we would call 'cp -al'): $ linkcp r3 r4 'checklink' is produced by hardlinking a symlink, which is undefined whether the symlink should be followed or not. It does behave differently on Linux and BSD. Just remove it so the test pass on both platforms. $ rm -f r4/.hg/cache/checklink r4 has hardlinks in the working dir (not just inside .hg): $ nlinksdir r4 2 r4/.hg/00changelog.i 2 r4/.hg/branch 2 r4/.hg/cache/branch2-base 2 r4/.hg/cache/branch2-served 2 r4/.hg/cache/checkisexec (execbit !) ? r4/.hg/cache/checklink-target (glob) (symlink !) 2 r4/.hg/cache/checknoexec (execbit !) 2 r4/.hg/cache/rbc-names-v1 2 r4/.hg/cache/rbc-revs-v1 2 r4/.hg/dirstate 2 r4/.hg/fsmonitor.state (fsmonitor !) 2 r4/.hg/hgrc 2 r4/.hg/last-message.txt 2 r4/.hg/requires 2 r4/.hg/store/00changelog.i 2 r4/.hg/store/00manifest.i 2 r4/.hg/store/data/d1/f2.d 2 r4/.hg/store/data/d1/f2.i 2 r4/.hg/store/data/f1.i 2 r4/.hg/store/data/f3.i 2 r4/.hg/store/fncache (repofncache !) 2 r4/.hg/store/phaseroots 2 r4/.hg/store/undo 2 r4/.hg/store/undo.backup.fncache (repofncache !) 2 r4/.hg/store/undo.backup.phaseroots 2 r4/.hg/store/undo.backupfiles 2 r4/.hg/store/undo.phaseroots [24] r4/\.hg/undo\.backup\.dirstate (re) 2 r4/.hg/undo.bookmarks 2 r4/.hg/undo.branch 2 r4/.hg/undo.desc [24] r4/\.hg/undo\.dirstate (re) 2 r4/d1/data1 2 r4/d1/f2 2 r4/f1 2 r4/f3 Update back to revision 12 in r4 should break hardlink of file f1 and f3: #if hardlink-whitelisted $ nlinksdir r4/.hg/undo.backup.dirstate r4/.hg/undo.dirstate 4 r4/.hg/undo.backup.dirstate 4 r4/.hg/undo.dirstate #endif $ hg -R r4 up 12 2 files updated, 0 files merged, 0 files removed, 0 files unresolved (execbit !) 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-execbit !) $ nlinksdir r4 2 r4/.hg/00changelog.i 1 r4/.hg/branch 2 r4/.hg/cache/branch2-base 2 r4/.hg/cache/branch2-served 2 r4/.hg/cache/checkisexec (execbit !) 2 r4/.hg/cache/checklink-target (symlink !) 2 r4/.hg/cache/checknoexec (execbit !) 2 r4/.hg/cache/rbc-names-v1 2 r4/.hg/cache/rbc-revs-v1 1 r4/.hg/dirstate 1 r4/.hg/fsmonitor.state (fsmonitor !) 2 r4/.hg/hgrc 2 r4/.hg/last-message.txt 2 r4/.hg/requires 2 r4/.hg/store/00changelog.i 2 r4/.hg/store/00manifest.i 2 r4/.hg/store/data/d1/f2.d 2 r4/.hg/store/data/d1/f2.i 2 r4/.hg/store/data/f1.i 2 r4/.hg/store/data/f3.i 2 r4/.hg/store/fncache 2 r4/.hg/store/phaseroots 2 r4/.hg/store/undo 2 r4/.hg/store/undo.backup.fncache (repofncache !) 2 r4/.hg/store/undo.backup.phaseroots 2 r4/.hg/store/undo.backupfiles 2 r4/.hg/store/undo.phaseroots [24] r4/\.hg/undo\.backup\.dirstate (re) 2 r4/.hg/undo.bookmarks 2 r4/.hg/undo.branch 2 r4/.hg/undo.desc [24] r4/\.hg/undo\.dirstate (re) 2 r4/d1/data1 2 r4/d1/f2 1 r4/f1 1 r4/f3 (execbit !) 2 r4/f3 (no-execbit !) #if hardlink-whitelisted $ nlinksdir r4/.hg/undo.backup.dirstate r4/.hg/undo.dirstate 4 r4/.hg/undo.backup.dirstate 4 r4/.hg/undo.dirstate #endif Test hardlinking outside hg: $ mkdir x $ echo foo > x/a $ linkcp x y $ echo bar >> y/a No diff if hardlink: $ diff x/a y/a Test mq hardlinking: $ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init a $ cd a $ hg qimport -n foo - << EOF > # HG changeset patch > # Date 1 0 > diff -r 2588a8b53d66 a > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/a Wed Jul 23 15:54:29 2008 +0200 > @@ -0,0 +1,1 @@ > +a > EOF adding foo to series file $ hg qpush applying foo now at: foo $ cd .. $ linkcp a b $ cd b $ hg qimport -n bar - << EOF > # HG changeset patch > # Date 2 0 > diff -r 2588a8b53d66 a > --- /dev/null Thu Jan 01 00:00:00 1970 +0000 > +++ b/b Wed Jul 23 15:54:29 2008 +0200 > @@ -0,0 +1,1 @@ > +b > EOF adding bar to series file $ hg qpush applying bar now at: bar $ cat .hg/patches/status 430ed4828a74fa4047bc816a25500f7472ab4bfe:foo 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c:bar $ cat .hg/patches/series foo bar $ cat ../a/.hg/patches/status 430ed4828a74fa4047bc816a25500f7472ab4bfe:foo $ cat ../a/.hg/patches/series foo Test tags hardlinking: $ hg qdel -r qbase:qtip patch foo finalized without changeset message patch bar finalized without changeset message $ hg tag -l lfoo $ hg tag foo $ cd .. $ linkcp b c $ cd c $ hg tag -l -r 0 lbar $ hg tag -r 0 bar $ cat .hgtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo 430ed4828a74fa4047bc816a25500f7472ab4bfe bar $ cat .hg/localtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo 430ed4828a74fa4047bc816a25500f7472ab4bfe lbar $ cat ../b/.hgtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c foo $ cat ../b/.hg/localtags 4e7abb4840c46a910f6d7b4d3c3fc7e5209e684c lfoo $ cd ..