view tests/test-basic.t @ 51681:522b4d729e89

mmap: populate the mapping by default Without pre-population, accessing all data through a mmap can result in many pagefault, reducing performance significantly. If the mmap is prepopulated, the performance can no longer get slower than a full read. (See benchmark number below) In some cases were very few data is read, prepopulating can be overkill and slower than populating on access (through page fault). So that behavior can be controlled when the caller can pre-determine the best behavior. (See benchmark number below) In addition, testing with populating in a secondary thread yield great result combining the best of each approach. This might be implemented in later changesets. In all cases, using mmap has a great effect on memory usage when many processes run in parallel on the same machine. ### Benchmarks # What did I run A couple of month back I ran a large benchmark campaign to assess the impact of various approach for using mmap with the revlog (and other files), it highlighted a few benchmarks that capture the impact of the changes well. So to validate this change I checked the following: - log command displaying various revisions (read the changelog index) - log command displaying the patch of listed revisions (read the changelog index, the manifest index and a few files indexes) - unbundling a few revisions (read and write changelog, manifest and few files indexes, and walk the graph to update some cache) - pushing a few revisions (read and write changelog, manifest and few files indexes, walk the graph to update some cache, performs various accesses locally and remotely during discovery) Benchmarks were run using the default module policy (c+py) and the rust one. No significant difference were found between the two implementation, so we will present result using the default policy (unless otherwise specified). I ran them on a few repositories : - mercurial: a "public changeset only" copy of mercurial from 2018-08-01 using zstd compression and sparse-revlog - pypy: a copy of pypy from 2018-08-01 using zstd compression and sparse-revlog - netbeans: a copy of netbeans from 2018-08-01 using zstd compression and sparse-revlog - mozilla-try: a copy of mozilla-try from 2019-02-18 using zstd compression and sparse-revlog - mozilla-try persistent-nodemap: Same as the above but with a persistent nodemap. Used for the log --patch benchmark only # Results For the smaller repositories (mercurial, pypy), the impact of mmap is almost imperceptible, other cost dominating the operation. The impact of prepopulating is undiscernible in the benchmark we ran. For larger repositories the benchmark support explanation given above: On netbeans, the log can be about 1% faster without repopulation (for a difference < 100ms) but unbundle becomes a bit slower, even when small. ### data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog # benchmark.name = hg.command.unbundle # benchmark.variants.issue6528 = disabled # benchmark.variants.reuse-external-delta-parent = yes # benchmark.variants.revs = any-1-extra-rev # benchmark.variants.source = unbundle # benchmark.variants.verbosity = quiet with-populate: 0.240157 no-populate: 0.265087 (+10.38%, +0.02) # benchmark.variants.revs = any-100-extra-rev with-populate: 1.459518 no-populate: 1.481290 (+1.49%, +0.02) ## benchmark.name = hg.command.push # benchmark.variants.explicit-rev = none # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.reuse-external-delta-parent = yes # benchmark.variants.revs = any-1-extra-rev with-populate: 0.771919 no-populate: 0.792025 (+2.60%, +0.02) # benchmark.variants.revs = any-100-extra-rev with-populate: 1.459518 no-populate: 1.481290 (+1.49%, +0.02) For mozilla-try, the "slow down" from pre-populate for small `hg log` is more visible, but still small in absolute time. (using rust value for the persistent nodemap value to be relevant). ### data-env-vars.name = mozilla-try-2019-02-18-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # benchmark.variants.patch = yes # benchmark.variants.limit-rev = 1 with-populate: 0.237813 no-populate: 0.229452 (-3.52%, -0.01) # benchmark.variants.limit-rev = 10 # benchmark.variants.patch = yes with-populate: 1.213578 no-populate: 1.205189 ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.variants.limit-rev = 1000 # benchmark.variants.patch = no # benchmark.variants.rev = tip with-populate: 0.198607 no-populate: 0.195038 (-1.80%, -0.00) However pre-populating provide a significant boost on more complex operations like unbundle or push: ### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog # benchmark.name = hg.command.push # benchmark.variants.explicit-rev = none # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.reuse-external-delta-parent = yes # benchmark.variants.revs = any-1-extra-rev with-populate: 4.798632 no-populate: 4.953295 (+3.22%, +0.15) # benchmark.variants.revs = any-100-extra-rev with-populate: 4.903618 no-populate: 5.014963 (+2.27%, +0.11) ## benchmark.name = hg.command.unbundle # benchmark.variants.revs = any-1-extra-rev with-populate: 1.423411 no-populate: 1.585365 (+11.38%, +0.16) # benchmark.variants.revs = any-100-extra-rev with-populate: 1.537909 no-populate: 1.688489 (+9.79%, +0.15)
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Thu, 11 Apr 2024 00:02:07 +0200
parents c84844cd523a
children
line wrap: on
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Create a repository:

#if no-extraextensions
  $ hg config
  chgserver.idletimeout=60
  devel.all-warnings=true
  devel.default-date=0 0
  extensions.fsmonitor= (fsmonitor !)
  format.use-dirstate-v2=1 (dirstate-v2 !)
  largefiles.usercache=$TESTTMP/.cache/largefiles
  lfs.usercache=$TESTTMP/.cache/lfs
  ui.slash=True
  ui.interactive=False
  ui.detailed-exit-code=True
  ui.merge=internal:merge
  ui.mergemarkers=detailed
  ui.promptecho=True
  ui.ssh=* (glob)
  ui.timeout.warn=15
  web.address=localhost
  web\.ipv6=(?:True|False) (re)
  web.server-header=testing stub value
#endif

  $ hg init t
  $ cd t

Prepare a changeset:

  $ echo a > a
  $ hg add a

  $ hg status
  A a

Writes to stdio succeed and fail appropriately

#if devfull
  $ hg status 2>/dev/full
  A a

  $ hg status >/dev/full
  abort: No space left on device* (glob)
  [255]
#endif

#if devfull
  $ hg status >/dev/full 2>&1
  [255]

  $ hg status ENOENT 2>/dev/full
  [255]
#endif

On Python 3, stdio may be None:

  $ hg debuguiprompt --config ui.interactive=true 0<&-
   abort: Bad file descriptor (no-rhg !)
   abort: response expected (rhg !)
  [255]
  $ hg version -q 0<&-
  Mercurial Distributed SCM * (glob)

#if py3 no-rhg
  $ hg version -q 1>&-
  abort: Bad file descriptor
  [255]
#else
  $ hg version -q 1>&-
#endif
  $ hg unknown -q 1>&-
  hg: unknown command 'unknown'
  (did you mean debugknown?)
  [10]

  $ hg version -q 2>&-
  Mercurial Distributed SCM * (glob)
  $ hg unknown -q 2>&-
  [10]

  $ hg commit -m test

This command is ancient:

  $ hg history
  changeset:   0:acb14030fe0a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     test
  

Verify that updating to revision 0 via commands.update() works properly

  $ cat <<EOF > update_to_rev0.py
  > from mercurial import commands, hg, ui as uimod
  > myui = uimod.ui.load()
  > repo = hg.repository(myui, path=b'.')
  > commands.update(myui, repo, rev=b"0")
  > EOF
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ "$PYTHON" ./update_to_rev0.py
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg identify -n
  0


Poke around at hashes:

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a

  $ hg cat a
  a

Verify should succeed:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checking dirstate
  checked 1 changesets with 1 changes to 1 files

Repository root:

  $ hg root
  $TESTTMP/t
  $ hg log -l1 -T '{reporoot}\n'
  $TESTTMP/t
  $ hg root -Tjson | sed 's|\\\\|\\|g'
  [
   {
    "hgpath": "$TESTTMP/t/.hg",
    "reporoot": "$TESTTMP/t",
    "storepath": "$TESTTMP/t/.hg/store"
   }
  ]

At the end...

  $ cd ..

Status message redirection:

  $ hg init empty

 status messages are sent to stdout by default:

  $ hg outgoing -R t empty -Tjson 2>/dev/null
  comparing with empty
  searching for changes
  [
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "test",
    "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
    "parents": ["0000000000000000000000000000000000000000"],
    "phase": "draft",
    "rev": 0,
    "tags": ["tip"],
    "user": "test"
   }
  ]

 which can be configured to send to stderr, so the output wouldn't be
 interleaved:

  $ cat <<'EOF' >> "$HGRCPATH"
  > [ui]
  > message-output = stderr
  > EOF
  $ hg outgoing -R t empty -Tjson 2>/dev/null
  [
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "test",
    "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
    "parents": ["0000000000000000000000000000000000000000"],
    "phase": "draft",
    "rev": 0,
    "tags": ["tip"],
    "user": "test"
   }
  ]
  $ hg outgoing -R t empty -Tjson >/dev/null
  comparing with empty
  searching for changes

 this option should be turned off by HGPLAIN= since it may break scripting use:

  $ HGPLAIN= hg outgoing -R t empty -Tjson 2>/dev/null
  comparing with empty
  searching for changes
  [
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "test",
    "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
    "parents": ["0000000000000000000000000000000000000000"],
    "phase": "draft",
    "rev": 0,
    "tags": ["tip"],
    "user": "test"
   }
  ]

 but still overridden by --config:

  $ HGPLAIN= hg outgoing -R t empty -Tjson --config ui.message-output=stderr \
  > 2>/dev/null
  [
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "test",
    "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
    "parents": ["0000000000000000000000000000000000000000"],
    "phase": "draft",
    "rev": 0,
    "tags": ["tip"],
    "user": "test"
   }
  ]

Invalid ui.message-output option:

  $ hg log -R t --config ui.message-output=bad
  abort: invalid ui.message-output destination: bad
  [255]

Underlying message streams should be updated when ui.fout/ferr are set:

  $ cat <<'EOF' > capui.py
  > import io
  > from mercurial import registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'capui', norepo=True)
  > def capui(ui):
  >     out = ui.fout
  >     ui.fout = io.BytesIO()
  >     ui.status(b'status\n')
  >     ui.ferr = io.BytesIO()
  >     ui.warn(b'warn\n')
  >     out.write(b'stdout: %s' % ui.fout.getvalue())
  >     out.write(b'stderr: %s' % ui.ferr.getvalue())
  > EOF
  $ hg --config extensions.capui=capui.py --config ui.message-output=stdio capui
  stdout: status
  stderr: warn