Mercurial > hg
view tests/test-http-clone-r.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 | eb586ed5d8ce |
| children | 89630d0b3e23 |
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#require serve creating 'remote $ hg init remote $ cd remote $ hg unbundle "$TESTDIR/bundles/remote.hg" adding changesets adding manifests adding file changes added 9 changesets with 7 changes to 4 files (+1 heads) new changesets bfaf4b5cbf01:916f1afdef90 (run 'hg heads' to see heads, 'hg merge' to merge) $ hg up tip 1 files updated, 0 files merged, 0 files removed, 0 files unresolved Starting server $ hg serve -p $HGPORT -E ../error.log -d --pid-file=../hg1.pid $ cd .. $ cat hg1.pid >> $DAEMON_PIDS clone remote via stream $ for i in 0 1 2 3 4 5 6 7 8; do > hg clone -r "$i" http://localhost:$HGPORT/ test-"$i" > if cd test-"$i"; then > hg verify > cd .. > fi > done adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files new changesets bfaf4b5cbf01 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 1 changesets, 1 total revisions adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets bfaf4b5cbf01:21f32785131f updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 2 changesets, 2 total revisions adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets bfaf4b5cbf01:4ce51a113780 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions adding changesets adding manifests adding file changes added 4 changesets with 4 changes to 1 files new changesets bfaf4b5cbf01:93ee6ab32777 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 4 changesets, 4 total revisions adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets bfaf4b5cbf01:c70afb1ee985 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 2 changesets, 2 total revisions adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets bfaf4b5cbf01:f03ae5a9b979 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 3 total revisions adding changesets adding manifests adding file changes added 4 changesets with 5 changes to 2 files new changesets bfaf4b5cbf01:095cb14b1b4d updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 4 changesets, 5 total revisions adding changesets adding manifests adding file changes added 5 changesets with 6 changes to 3 files new changesets bfaf4b5cbf01:faa2e4234c7a updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 3 files, 5 changesets, 6 total revisions adding changesets adding manifests adding file changes added 5 changesets with 5 changes to 2 files new changesets bfaf4b5cbf01:916f1afdef90 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files 2 files, 5 changesets, 5 total revisions $ cd test-8 $ hg pull ../test-7 pulling from ../test-7 searching for changes adding changesets adding manifests adding file changes added 4 changesets with 2 changes to 3 files (+1 heads) new changesets c70afb1ee985:faa2e4234c7a (run 'hg heads' to see heads, 'hg merge' to merge) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 9 changesets, 7 total revisions $ cd .. $ cd test-1 $ hg pull -r 4 http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 1 changesets with 0 changes to 0 files (+1 heads) new changesets c70afb1ee985 (run 'hg heads' to see heads, 'hg merge' to merge) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 3 changesets, 2 total revisions $ hg pull http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 6 changesets with 5 changes to 4 files new changesets 4ce51a113780:916f1afdef90 (run 'hg update' to get a working copy) $ cd .. $ cd test-2 $ hg pull -r 5 http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 2 changesets with 0 changes to 0 files (+1 heads) new changesets c70afb1ee985:f03ae5a9b979 (run 'hg heads' to see heads, 'hg merge' to merge) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 5 changesets, 3 total revisions $ hg pull http://localhost:$HGPORT/ pulling from http://localhost:$HGPORT/ searching for changes adding changesets adding manifests adding file changes added 4 changesets with 4 changes to 4 files new changesets 93ee6ab32777:916f1afdef90 (run 'hg update' to get a working copy) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 4 files, 9 changesets, 7 total revisions $ cd .. no default destination if url has no path: $ hg clone http://localhost:$HGPORT/ abort: empty destination path is not valid [255] $ cat error.log