view tests/test-mq-qpush-exact.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

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

make a test repository that looks like this:

o    2:28bc7b1afd6a
|
| @  1:d7fe2034f71b
|/
o    0/62ecad8b70e5

  $ hg init r0
  $ cd r0
  $ touch f0
  $ hg ci -m0 -Aq
  $ touch f1
  $ hg ci -m1 -Aq

  $ hg update 0 -q
  $ touch f2
  $ hg ci -m2 -Aq
  $ hg update 1 -q

make some patches with a parent: 1:d7fe2034f71b -> p0 -> p1

  $ echo cp0 >> fp0
  $ hg add fp0
  $ hg ci -m p0 -d "0 0"
  $ hg export -r. > p0
  $ hg strip -qn .
  $ hg qimport p0
  adding p0 to series file
  $ hg qpush
  applying p0
  now at: p0

  $ echo cp1 >> fp1
  $ hg add fp1
  $ hg qnew p1 -d "0 0"

  $ hg qpop -aq
  patch queue now empty

qpush --exact when at the parent

  $ hg update 1 -q
  $ hg qpush -e
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg qpush -e p0
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg qpush -e p1
  applying p0
  applying p1
  now at: p1
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

qpush --exact when at another rev

  $ hg update 0 -q
  $ hg qpush -e
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 0 -q
  $ hg qpush -e p0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 0 -q
  $ hg qpush -e p1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  applying p0
  applying p1
  now at: p1
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 0 -q
  $ hg qpush -ea
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  applying p0
  applying p1
  now at: p1
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

qpush --exact while crossing branches

  $ hg update 2 -q
  $ hg qpush -e
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 2 -q
  $ hg qpush -e p0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  applying p0
  now at: p0
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 2 -q
  $ hg qpush -e p1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  applying p0
  applying p1
  now at: p1
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

  $ hg update 2 -q
  $ hg qpush -ea
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  applying p0
  applying p1
  now at: p1
  $ hg parents -qr qbase
  1:d7fe2034f71b
  $ hg qpop -aq
  patch queue now empty

qpush --exact --force with changes to an unpatched file

  $ hg update 1 -q
  $ echo c0 >> f0
  $ hg qpush -e
  abort: local changes found
  [255]
  $ hg qpush -ef
  applying p0
  now at: p0
  $ cat f0
  c0
  $ rm f0
  $ touch f0
  $ hg qpop -aq
  patch queue now empty

  $ hg update 1 -q
  $ echo c0 >> f0
  $ hg qpush -e p1
  abort: local changes found
  [255]
  $ hg qpush -e p1 -f
  applying p0
  applying p1
  now at: p1
  $ cat f0
  c0
  $ rm f0
  $ touch f0
  $ hg qpop -aq
  patch queue now empty

qpush --exact --force with changes to a patched file

  $ hg update 1 -q
  $ echo cp0-bad >> fp0
  $ hg add fp0
  $ hg qpush -e
  abort: local changes found
  [255]
  $ hg qpush -ef
  applying p0
  file fp0 already exists
  1 out of 1 hunks FAILED -- saving rejects to file fp0.rej
  patch failed, unable to continue (try -v)
  patch failed, rejects left in working directory
  errors during apply, please fix and qrefresh p0
  [2]
  $ cat fp0
  cp0-bad
  $ cat fp0.rej
  --- fp0
  +++ fp0
  @@ -0,0 +1,1 @@
  +cp0
  $ hg qpop -aqf
  patch queue now empty
  $ rm fp0
  $ rm fp0.rej

  $ hg update 1 -q
  $ echo cp1-bad >> fp1
  $ hg add fp1
  $ hg qpush -e p1
  abort: local changes found
  [255]
  $ hg qpush -e p1 -f
  applying p0
  applying p1
  file fp1 already exists
  1 out of 1 hunks FAILED -- saving rejects to file fp1.rej
  patch failed, unable to continue (try -v)
  patch failed, rejects left in working directory
  errors during apply, please fix and qrefresh p1
  [2]
  $ cat fp1
  cp1-bad
  $ cat fp1.rej
  --- fp1
  +++ fp1
  @@ -0,0 +1,1 @@
  +cp1
  $ hg qpop -aqf
  patch queue now empty
  $ hg forget fp1
  $ rm fp1
  $ rm fp1.rej

qpush --exact when already at a patch

  $ hg update 1
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg qpush -e p0
  applying p0
  now at: p0
  $ hg qpush -e p1
  abort: cannot push --exact with applied patches
  [255]
  $ hg qpop -aq
  patch queue now empty

qpush --exact --move should fail

  $ hg qpush -e --move p1
  abort: cannot use --exact and --move together
  [255]

qpush --exact a patch without a parent recorded

  $ hg qpush -q
  now at: p0
  $ grep -v '# Parent' .hg/patches/p0 > p0.new
  $ mv p0.new .hg/patches/p0
  $ hg qpop -aq
  patch queue now empty
  $ hg qpush -e
  abort: p0 does not have a parent recorded
  [255]
  $ hg qpush -e p0
  abort: p0 does not have a parent recorded
  [255]
  $ hg qpush -e p1
  abort: p0 does not have a parent recorded
  [255]
  $ hg qpush -ea
  abort: p0 does not have a parent recorded
  [255]

  $ cd ..