view tests/test-exchange-obsmarkers-case-A1.t @ 33207:895ecec31c70

revlog: add an experimental option to mitigated delta issues (issue5480)

The general delta heuristic to select a delta do not scale with the number of
branch. The delta base is frequently too far away to be able to reuse a chain
according to the "distance" criteria. This leads to insertion of larger delta (or
even full text) that themselves push the bases for the next delta further away
leading to more large deltas and full texts. This full text and frequent
recomputation throw Mercurial performance in disarray.

For example of a slightly large repository

  280 000 files (2 150 000 versions)
  430 000 changesets (10 000 topological heads)

Number below compares repository with and without the distance criteria:

manifest size:
    with:    21.4 GB
    without:  0.3 GB

store size:
    with:    28.7 GB
    without   7.4 GB

bundle last 15 00 revisions:
    with:    800 seconds
             971 MB
    without:  50 seconds
              73 MB

unbundle time (of the last 15K revisions):
    with:    1150 seconds (~19 minutes)
    without:   35 seconds

Similar issues has been observed in other repositories.


Adding a new option or "feature" on stable is uncommon. However, given that this
issues is making Mercurial practically unusable, I'm exceptionally targeting
this patch for stable.

What is actually needed is a full rework of the delta building and reading
logic. However, that will be a longer process and churn not suitable for stable.

In the meantime, we introduces a quick and dirty mitigation of this in the
'experimental' config space. The new option introduces a way to set the maximum
amount of memory usable to store a diff in memory. This extend the ability for
Mercurial to create chains without removing all safe guard regarding memory
access. The option should be phased out when core has a more proper solution
available.

Setting the limit to '0' remove all limits, setting it to '-1' use the default
limit (textsize x 4).

============================================
Testing obsolescence markers push: Cases A.1
============================================

Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).

This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.

Category A: simple cases
TestCase 1: pushing a single head
Subcases:
# A.1.1 pushing a single head (2 variants)
# A.1.2 pushing multiple changesets into a single head (2 variants)

Case: A.1.1 pushing a single head
=================================
..
.. {{{
..     ⇠◔ A
..      |
..      ● O
.. }}}
..
.. Marker exists from:
..
..  * A
..
.. Commands run:
..
..  * hg push -r A
..  * hg push
..
.. Expected exchange:
..
..  * chain from A

Setup
-----

  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh

initial

  $ setuprepos A.1.1
  creating test repo for test case A.1.1
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A)'`
  $ hg log -G
  @  f5bc6836db60 (draft): A
  |
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

setup both variants

  $ cp -R A.1.1 A.1.1.a
  $ cp -R A.1.1 A.1.1.b

Variant a: push -r A
--------------------

  $ dotest A.1.1.a A
  ## Running testcase A.1.1.a
  # testing echange of "A" (f5bc6836db60)
  ## initial state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "A" from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling "f5bc6836db60" from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  1 new obsolescence markers
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}

Variant b: push
---------------

  $ dotest A.1.1.b
  ## Running testcase A.1.1.b
  ## initial state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  1 new obsolescence markers
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}

A.1.2 pushing multiple changesets into a single head
====================================================

.. {{{
..      ◔ B
..      |
..     ⇠◔ A
..      |
..      ● O
.. }}}
..
.. Marker exist from:
..
..  * A
..
.. Command run:
..
..  * hg push -r B
..  * hg push
..
.. Expected exchange:
..
..  * chain from A

Setup
-----

initial

  $ setuprepos A.1.2
  creating test repo for test case A.1.2
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A
  $ mkcommit B
  $ hg log -G
  @  f6fbb35d8ac9 (draft): B
  |
  o  f5bc6836db60 (draft): A
  |
  o  a9bdc8b26820 (public): O
  
  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A)'`
  $ inspect_obsmarkers
  obsstore content
  ================
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

setup both variants

  $ cp -R A.1.2 A.1.2.a
  $ cp -R A.1.2 A.1.2.b

Variant a: push -r A
--------------------

  $ dotest A.1.2.a B
  ## Running testcase A.1.2.a
  # testing echange of "B" (f6fbb35d8ac9)
  ## initial state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "B" from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 2 changesets with 2 changes to 2 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling "f6fbb35d8ac9" from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  1 new obsolescence markers
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}

Variant b: push
---------------

  $ dotest A.1.2.b
  ## Running testcase A.1.2.b
  ## initial state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 2 changesets with 2 changes to 2 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  1 new obsolescence markers
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}