Mercurial > hg
view tests/test-dirstate-race.t @ 47120:7109a38830c9
dirstate-tree: Fold "tracked descendants" counter update in main walk
For the purpose of implementing `has_tracked_dir` (which means "has tracked
descendants) without an expensive sub-tree traversal, we maintaing a counter
of tracked descendants on each "directory" node of the tree-shaped dirstate.
Before this changeset, mutating or inserting a node at a given path would
involve:
* Walking the tree from root through ancestors to find the node or the spot
where to insert it
* Looking at the previous node if any to decide what counter update is needed
* Performing any node mutation
* Walking the tree *again* to update counters in ancestor nodes
When profiling `hg status` on a large repo, this second walk takes times
while loading a the dirstate from disk.
It turns out we have enough information to decide before he first tree walk
what counter update is needed. This changeset merges the two walks, gaining
~10% of the total time for `hg update` (in the same hyperfine benchmark as
the previous changeset).
---
Profiling was done by compiling with this `.cargo/config`:
[profile.release]
debug = true
then running with:
py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \
./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1
then visualizing the recorded JSON file in https://www.speedscope.app/
Differential Revision: https://phab.mercurial-scm.org/D10554
author | Simon Sapin <simon.sapin@octobus.net> |
---|---|
date | Fri, 30 Apr 2021 14:22:14 +0200 |
parents | f90a5c211251 |
children | 93eb6c8035a9 |
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$ hg init repo $ cd repo $ echo a > a $ hg add a $ hg commit -m test Do we ever miss a sub-second change?: $ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do > hg co -qC 0 > echo b > a > hg st > done M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a M a $ echo test > b $ mkdir dir1 $ echo test > dir1/c $ echo test > d $ echo test > e #if execbit A directory will typically have the execute bit -- make sure it doesn't get confused with a file with the exec bit set $ chmod +x e #endif $ hg add b dir1 d e adding dir1/c $ hg commit -m test2 $ cat >> $TESTTMP/dirstaterace.py << EOF > from mercurial import ( > context, > extensions, > ) > def extsetup(ui): > extensions.wrapfunction(context.workingctx, '_checklookup', overridechecklookup) > def overridechecklookup(orig, self, files): > # make an update that changes the dirstate from underneath > self._repo.ui.system(br"sh '$TESTTMP/dirstaterace.sh'", > cwd=self._repo.root) > return orig(self, files) > EOF $ hg debugrebuilddirstate $ hg debugdirstate n 0 -1 unset a n 0 -1 unset b n 0 -1 unset d n 0 -1 unset dir1/c n 0 -1 unset e XXX Note that this returns M for files that got replaced by directories. This is definitely a bug, but the fix for that is hard and the next status run is fine anyway. $ cat > $TESTTMP/dirstaterace.sh <<EOF > rm b && rm -r dir1 && rm d && mkdir d && rm e && mkdir e > EOF $ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py M d M e ! b ! dir1/c $ hg debugdirstate n 644 2 * a (glob) n 0 -1 unset b n 0 -1 unset d n 0 -1 unset dir1/c n 0 -1 unset e $ hg status ! b ! d ! dir1/c ! e $ rmdir d e $ hg update -C -q . Test that dirstate changes aren't written out at the end of "hg status", if .hg/dirstate is already changed simultaneously before acquisition of wlock in workingctx._poststatusfixup(). This avoidance is important to keep consistency of dirstate in race condition (see issue5584 for detail). $ hg parents -q 1:* (glob) $ hg debugrebuilddirstate $ hg debugdirstate n 0 -1 unset a n 0 -1 unset b n 0 -1 unset d n 0 -1 unset dir1/c n 0 -1 unset e $ cat > $TESTTMP/dirstaterace.sh <<EOF > # This script assumes timetable of typical issue5584 case below: > # > # 1. "hg status" loads .hg/dirstate > # 2. "hg status" confirms clean-ness of FILE > # 3. "hg update -C 0" updates the working directory simultaneously > # (FILE is removed, and FILE is dropped from .hg/dirstate) > # 4. "hg status" acquires wlock > # (.hg/dirstate is re-loaded = no FILE entry in dirstate) > # 5. "hg status" marks FILE in dirstate as clean > # (FILE entry is added to in-memory dirstate) > # 6. "hg status" writes dirstate changes into .hg/dirstate > # (FILE entry is written into .hg/dirstate) > # > # To reproduce similar situation easily and certainly, #2 and #3 > # are swapped. "hg cat" below ensures #2 on "hg status" side. > > hg update -q -C 0 > hg cat -r 1 b > b > EOF "hg status" below should excludes "e", of which exec flag is set, for portability of test scenario, because unsure but missing "e" is treated differently in _checklookup() according to runtime platform. - "missing(!)" on POSIX, "pctx[f].cmp(self[f])" raises ENOENT - "modified(M)" on Windows, "self.flags(f) != pctx.flags(f)" is True $ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py --debug -X path:e skip updating dirstate: identity mismatch M a ! d ! dir1/c $ hg parents -q 0:* (glob) $ hg files a $ hg debugdirstate n * * * a (glob) $ rm b #if fsmonitor Create fsmonitor state. $ hg status $ f --type .hg/fsmonitor.state .hg/fsmonitor.state: file Test that invalidating fsmonitor state in the middle (which doesn't require the wlock) causes the fsmonitor update to be skipped. hg debugrebuilddirstate ensures that the dirstaterace hook will be called, but it also invalidates the fsmonitor state. So back it up and restore it. $ mv .hg/fsmonitor.state .hg/fsmonitor.state.tmp $ hg debugrebuilddirstate $ mv .hg/fsmonitor.state.tmp .hg/fsmonitor.state $ cat > $TESTTMP/dirstaterace.sh <<EOF > rm .hg/fsmonitor.state > EOF $ hg status --config extensions.dirstaterace=$TESTTMP/dirstaterace.py --debug skip updating fsmonitor.state: identity mismatch $ f .hg/fsmonitor.state .hg/fsmonitor.state: file not found #endif Set up a rebase situation for issue5581. $ echo c2 > a $ echo c2 > b $ hg add b $ hg commit -m c2 created new head $ echo c3 >> a $ hg commit -m c3 $ hg update 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo c4 >> a $ echo c4 >> b $ hg commit -m c4 created new head Configure a merge tool that runs status in the middle of the rebase. The goal of the status call is to trigger a potential bug if fsmonitor's state is written even though the wlock is held by another process. The output of 'hg status' in the merge tool goes to /dev/null because we're more interested in the results of 'hg status' run after the rebase. $ cat >> $TESTTMP/mergetool-race.sh << EOF > echo "custom merge tool" > printf "c2\nc3\nc4\n" > \$1 > hg --cwd "$TESTTMP/repo" status > /dev/null > echo "custom merge tool end" > EOF $ cat >> $HGRCPATH << EOF > [extensions] > rebase = > [merge-tools] > test.executable=sh > test.args=$TESTTMP/mergetool-race.sh \$output > EOF $ hg rebase -s . -d 3 --tool test rebasing 4:b08445fd6b2a tip "c4" merging a custom merge tool custom merge tool end saved backup bundle to $TESTTMP/repo/.hg/strip-backup/* (glob) This hg status should be empty, whether or not fsmonitor is enabled (issue5581). $ hg status