view tests/test-ssh-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

This test tries to exercise the ssh functionality with a dummy script

#testcases sshv1 sshv2

#if sshv2
  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > sshpeer.advertise-v2 = true
  > sshserver.support-v2 = true
  > EOF
#endif

creating 'remote' repo

  $ 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
  $ cd ..

clone remote via stream

  $ for i in 0 1 2 3 4 5 6 7 8; do
  >    hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" --stream -r "$i" ssh://user@dummy/remote test-"$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 -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" -r 4 ssh://user@dummy/remote
  pulling from ssh://user@dummy/remote
  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 -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote
  pulling from ssh://user@dummy/remote
  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 -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" -r 5 ssh://user@dummy/remote
  pulling from ssh://user@dummy/remote
  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 -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote
  pulling from ssh://user@dummy/remote
  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 ..