view tests/test-purge.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

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > purge =
  > EOF

init

  $ hg init t
  $ cd t

setup

  $ echo r1 > r1
  $ hg ci -qAmr1 -d'0 0'
  $ mkdir directory
  $ echo r2 > directory/r2
  $ hg ci -qAmr2 -d'1 0'
  $ echo 'ignored' > .hgignore
  $ hg ci -qAmr3 -d'2 0'

delete an empty directory

  $ mkdir empty_dir
  $ hg purge -p -v
  empty_dir
  $ hg purge -v
  removing directory empty_dir
  $ ls
  directory
  r1

delete an untracked directory

  $ mkdir untracked_dir
  $ touch untracked_dir/untracked_file1
  $ touch untracked_dir/untracked_file2
  $ hg purge -p
  untracked_dir/untracked_file1
  untracked_dir/untracked_file2
  $ hg purge -v
  removing file untracked_dir/untracked_file1
  removing file untracked_dir/untracked_file2
  removing directory untracked_dir
  $ ls
  directory
  r1

delete an untracked file

  $ touch untracked_file
  $ touch untracked_file_readonly
  $ $PYTHON <<EOF
  > import os, stat
  > f= 'untracked_file_readonly'
  > os.chmod(f, stat.S_IMODE(os.stat(f).st_mode) & ~stat.S_IWRITE)
  > EOF
  $ hg purge -p
  untracked_file
  untracked_file_readonly
  $ hg purge -v
  removing file untracked_file
  removing file untracked_file_readonly
  $ ls
  directory
  r1

delete an untracked file in a tracked directory

  $ touch directory/untracked_file
  $ hg purge -p
  directory/untracked_file
  $ hg purge -v
  removing file directory/untracked_file
  $ ls
  directory
  r1

delete nested directories

  $ mkdir -p untracked_directory/nested_directory
  $ hg purge -p
  untracked_directory/nested_directory
  $ hg purge -v
  removing directory untracked_directory/nested_directory
  removing directory untracked_directory
  $ ls
  directory
  r1

delete nested directories from a subdir

  $ mkdir -p untracked_directory/nested_directory
  $ cd directory
  $ hg purge -p
  untracked_directory/nested_directory
  $ hg purge -v
  removing directory untracked_directory/nested_directory
  removing directory untracked_directory
  $ cd ..
  $ ls
  directory
  r1

delete only part of the tree

  $ mkdir -p untracked_directory/nested_directory
  $ touch directory/untracked_file
  $ cd directory
  $ hg purge -p ../untracked_directory
  untracked_directory/nested_directory
  $ hg purge -v ../untracked_directory
  removing directory untracked_directory/nested_directory
  removing directory untracked_directory
  $ cd ..
  $ ls
  directory
  r1
  $ ls directory/untracked_file
  directory/untracked_file
  $ rm directory/untracked_file

skip ignored files if --all not specified

  $ touch ignored
  $ hg purge -p
  $ hg purge -v
  $ ls
  directory
  ignored
  r1
  $ hg purge -p --all
  ignored
  $ hg purge -v --all
  removing file ignored
  $ ls
  directory
  r1

abort with missing files until we support name mangling filesystems

  $ touch untracked_file
  $ rm r1

hide error messages to avoid changing the output when the text changes

  $ hg purge -p 2> /dev/null
  untracked_file
  $ hg st
  ! r1
  ? untracked_file

  $ hg purge -p
  untracked_file
  $ hg purge -v 2> /dev/null
  removing file untracked_file
  $ hg st
  ! r1

  $ hg purge -v
  $ hg revert --all --quiet
  $ hg st -a

tracked file in ignored directory (issue621)

  $ echo directory >> .hgignore
  $ hg ci -m 'ignore directory'
  $ touch untracked_file
  $ hg purge -p
  untracked_file
  $ hg purge -v
  removing file untracked_file

skip excluded files

  $ touch excluded_file
  $ hg purge -p -X excluded_file
  $ hg purge -v -X excluded_file
  $ ls
  directory
  excluded_file
  r1
  $ rm excluded_file

skip files in excluded dirs

  $ mkdir excluded_dir
  $ touch excluded_dir/file
  $ hg purge -p -X excluded_dir
  $ hg purge -v -X excluded_dir
  $ ls
  directory
  excluded_dir
  r1
  $ ls excluded_dir
  file
  $ rm -R excluded_dir

skip excluded empty dirs

  $ mkdir excluded_dir
  $ hg purge -p -X excluded_dir
  $ hg purge -v -X excluded_dir
  $ ls
  directory
  excluded_dir
  r1
  $ rmdir excluded_dir

skip patterns

  $ mkdir .svn
  $ touch .svn/foo
  $ mkdir directory/.svn
  $ touch directory/.svn/foo
  $ hg purge -p -X .svn -X '*/.svn'
  $ hg purge -p -X re:.*.svn

  $ rm -R .svn directory r1

only remove files

  $ mkdir -p empty_dir dir
  $ touch untracked_file dir/untracked_file
  $ hg purge -p --files
  dir/untracked_file
  untracked_file
  $ hg purge -v --files
  removing file dir/untracked_file
  removing file untracked_file
  $ ls
  dir
  empty_dir
  $ ls dir

only remove dirs

  $ mkdir -p empty_dir dir
  $ touch untracked_file dir/untracked_file
  $ hg purge -p --dirs
  empty_dir
  $ hg purge -v --dirs
  removing directory empty_dir
  $ ls
  dir
  untracked_file
  $ ls dir
  untracked_file

remove both files and dirs

  $ mkdir -p empty_dir dir
  $ touch untracked_file dir/untracked_file
  $ hg purge -p --files --dirs
  dir/untracked_file
  untracked_file
  empty_dir
  $ hg purge -v --files --dirs
  removing file dir/untracked_file
  removing file untracked_file
  removing directory empty_dir
  removing directory dir
  $ ls

  $ cd ..