Mercurial > hg
view tests/test-histedit-no-change.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 | e7ff83b2bcfe |
children | 527ce85c2e60 |
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test for old histedit issue #6: editing a changeset without any actual change would corrupt the repository $ . "$TESTDIR/histedit-helpers.sh" $ cat >> $HGRCPATH <<EOF > [extensions] > histedit= > EOF $ initrepo () > { > dir="$1" > comment="$2" > if [ -n "${comment}" ]; then > echo % ${comment} > echo % ${comment} | sed 's:.:-:g' > fi > hg init ${dir} > cd ${dir} > for x in a b c d e f ; do > echo $x > $x > hg add $x > hg ci -m $x > done > cd .. > } $ geneditor () > { > # generate an editor script for selecting changesets to be edited > choice=$1 # changesets that should be edited (using sed line ranges) > cat <<EOF | sed 's:^....::' > # editing the rules, replacing 'pick' with 'edit' for the chosen lines > sed '${choice}s:^pick:edit:' "\$1" > "\${1}.tmp" > mv "\${1}.tmp" "\$1" > # displaying the resulting rules, minus comments and empty lines > sed '/^#/d;/^$/d;s:^:| :' "\$1" >&2 > EOF > } $ startediting () > { > # begin an editing session > choice="$1" # changesets that should be edited > number="$2" # number of changesets considered (from tip) > comment="$3" > geneditor "${choice}" > edit.sh > echo % start editing the history ${comment} > HGEDITOR="sh ./edit.sh" hg histedit -- -${number} 2>&1 | fixbundle > } $ continueediting () > { > # continue an edit already in progress > editor="$1" # message editor when finalizing editing > comment="$2" > echo % finalize changeset editing ${comment} > HGEDITOR=${editor} hg histedit --continue 2>&1 | fixbundle > } $ graphlog () > { > comment="${1:-log}" > echo % "${comment}" > hg log -G --template '{rev} {node} \"{desc|firstline}\"\n' > } $ initrepo r1 "test editing with no change" % test editing with no change ----------------------------- $ cd r1 $ graphlog "log before editing" % log before editing @ 5 652413bf663ef2a641cab26574e46d5f5a64a55a "f" | o 4 e860deea161a2f77de56603b340ebbb4536308ae "e" | o 3 055a42cdd88768532f9cf79daa407fc8d138de9b "d" | o 2 177f92b773850b59254aa5e923436f921b55483b "c" | o 1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b" | o 0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a" $ startediting 2 3 "(not changing anything)" # edit the 2nd of 3 changesets % start editing the history (not changing anything) | pick 055a42cdd887 3 d | edit e860deea161a 4 e | pick 652413bf663e 5 f 0 files updated, 0 files merged, 2 files removed, 0 files unresolved Editing (e860deea161a), you may commit or record as needed now. (hg histedit --continue to resume) $ continueediting true "(leaving commit message unaltered)" % finalize changeset editing (leaving commit message unaltered) check state of working copy $ hg id 794fe033d0a0 tip $ graphlog "log after history editing" % log after history editing @ 5 794fe033d0a030f8df77c5de945fca35c9181c30 "f" | o 4 04d2fab980779f332dec458cc944f28de8b43435 "e" | o 3 055a42cdd88768532f9cf79daa407fc8d138de9b "d" | o 2 177f92b773850b59254aa5e923436f921b55483b "c" | o 1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b" | o 0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a" $ cd .. $ initrepo r2 "test editing with no change, then abort" % test editing with no change, then abort ----------------------------------------- $ cd r2 $ graphlog "log before editing" % log before editing @ 5 652413bf663ef2a641cab26574e46d5f5a64a55a "f" | o 4 e860deea161a2f77de56603b340ebbb4536308ae "e" | o 3 055a42cdd88768532f9cf79daa407fc8d138de9b "d" | o 2 177f92b773850b59254aa5e923436f921b55483b "c" | o 1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b" | o 0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a" $ startediting 1,2 3 "(not changing anything)" # edit the 1st two of 3 changesets % start editing the history (not changing anything) | edit 055a42cdd887 3 d | edit e860deea161a 4 e | pick 652413bf663e 5 f 0 files updated, 0 files merged, 3 files removed, 0 files unresolved Editing (055a42cdd887), you may commit or record as needed now. (hg histedit --continue to resume) $ continueediting true "(leaving commit message unaltered)" % finalize changeset editing (leaving commit message unaltered) Editing (e860deea161a), you may commit or record as needed now. (hg histedit --continue to resume) $ graphlog "log after first edit" % log after first edit @ 6 e5ae3ca2f1ffdbd89ec41ebc273a231f7c3022f2 "d" | | o 5 652413bf663ef2a641cab26574e46d5f5a64a55a "f" | | | o 4 e860deea161a2f77de56603b340ebbb4536308ae "e" | | | o 3 055a42cdd88768532f9cf79daa407fc8d138de9b "d" |/ o 2 177f92b773850b59254aa5e923436f921b55483b "c" | o 1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b" | o 0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a" abort editing session, after first forcibly updating away $ hg up 0 abort: histedit in progress (use 'hg histedit --continue' or 'hg histedit --abort') [255] $ mv .hg/histedit-state .hg/histedit-state-ignore $ hg up 0 0 files updated, 0 files merged, 3 files removed, 0 files unresolved $ mv .hg/histedit-state-ignore .hg/histedit-state $ hg sum parent: 0:cb9a9f314b8b a branch: default commit: 1 added, 1 unknown (new branch head) update: 6 new changesets (update) phases: 7 draft hist: 2 remaining (histedit --continue) $ hg histedit --abort 2>&1 | fixbundle modified files should survive the abort when we've moved away already $ hg st A e ? edit.sh $ graphlog "log after abort" % log after abort o 5 652413bf663ef2a641cab26574e46d5f5a64a55a "f" | o 4 e860deea161a2f77de56603b340ebbb4536308ae "e" | o 3 055a42cdd88768532f9cf79daa407fc8d138de9b "d" | o 2 177f92b773850b59254aa5e923436f921b55483b "c" | o 1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b" | @ 0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a" aborting and not changing files can skip mentioning updating (no) files $ hg up 5 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg commit --close-branch -m 'closebranch' $ startediting 1 1 "(not changing anything)" # edit the 3rd of 3 changesets % start editing the history (not changing anything) | edit 292aec348d9e 6 closebranch Editing (292aec348d9e), you may commit or record as needed now. (hg histedit --continue to resume) $ hg histedit --abort $ cd ..