Mercurial > hg
view tests/test-convert-bzr-directories.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 | 89872688893f |
children | 815e9ca1078c |
line wrap: on
line source
#require bzr $ . "$TESTDIR/bzr-definitions" empty directory $ mkdir test-empty $ cd test-empty $ bzr init -q source $ cd source $ echo content > a $ bzr add -q a $ bzr commit -q -m 'Initial add' $ mkdir empty $ bzr add -q empty $ bzr commit -q -m 'Empty directory added' $ echo content > empty/something $ bzr add -q empty/something $ bzr commit -q -m 'Added file into directory' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 2 Initial add 1 Empty directory added 0 Added file into directory $ manifest source-hg 1 % manifest of 1 644 a $ manifest source-hg tip % manifest of tip 644 a 644 empty/something $ cd .. directory renames $ mkdir test-dir-rename $ cd test-dir-rename $ bzr init -q source $ cd source $ mkdir tpyo $ echo content > tpyo/something $ bzr add -q tpyo $ bzr commit -q -m 'Added directory' $ bzr mv tpyo typo tpyo => typo $ bzr commit -q -m 'Oops, typo' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 1 Added directory 0 Oops, typo $ manifest source-hg 0 % manifest of 0 644 tpyo/something $ manifest source-hg tip % manifest of tip 644 typo/something $ cd .. nested directory renames $ mkdir test-nested-dir-rename $ cd test-nested-dir-rename $ bzr init -q source $ cd source $ mkdir -p firstlevel/secondlevel/thirdlevel $ echo content > firstlevel/secondlevel/file $ echo this_needs_to_be_there_too > firstlevel/secondlevel/thirdlevel/stuff $ bzr add -q firstlevel $ bzr commit -q -m 'Added nested directories' $ bzr mv firstlevel/secondlevel secondlevel firstlevel/secondlevel => secondlevel $ bzr commit -q -m 'Moved secondlevel one level up' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 1 Added nested directories 0 Moved secondlevel one level up $ manifest source-hg tip % manifest of tip 644 secondlevel/file 644 secondlevel/thirdlevel/stuff $ cd .. directory remove $ mkdir test-dir-remove $ cd test-dir-remove $ bzr init -q source $ cd source $ mkdir src $ echo content > src/sourcecode $ bzr add -q src $ bzr commit -q -m 'Added directory' $ bzr rm -q src $ bzr commit -q -m 'Removed directory' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 1 Added directory 0 Removed directory $ manifest source-hg 0 % manifest of 0 644 src/sourcecode $ manifest source-hg tip % manifest of tip $ cd .. directory replace $ mkdir test-dir-replace $ cd test-dir-replace $ bzr init -q source $ cd source $ mkdir first second $ echo content > first/file $ echo morecontent > first/dummy $ echo othercontent > second/something $ bzr add -q first second $ bzr commit -q -m 'Initial layout' $ bzr mv first/file second/file first/file => second/file $ bzr mv first third first => third $ bzr commit -q -m 'Some conflicting moves' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 1 Initial layout 0 Some conflicting moves $ manifest source-hg tip % manifest of tip 644 second/file 644 second/something 644 third/dummy $ cd .. divergent nested renames (issue3089) $ mkdir test-divergent-renames $ cd test-divergent-renames $ bzr init -q source $ cd source $ mkdir -p a/c $ echo a > a/fa $ echo c > a/c/fc $ bzr add -q a $ bzr commit -q -m 'Initial layout' $ bzr mv a b a => b $ mkdir a $ bzr add a add(ed|ing) a (re) $ bzr mv b/c a/c b/c => a/c $ bzr status added: a/ renamed: a/? => b/? (re) a/c/? => a/c/? (re) $ bzr commit -q -m 'Divergent renames' $ cd .. $ hg convert source source-hg initializing destination source-hg repository scanning source... sorting... converting... 1 Initial layout 0 Divergent renames $ hg -R source-hg st -C --change 1 A b/fa a/fa R a/fa $ hg -R source-hg manifest -r 1 a/c/fc b/fa $ cd ..