view tests/test-rebase-cache.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 >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > mq=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog  = log -G --template "{rev}: '{desc}' {branches}\n"
  > theads = heads --template "{rev}: '{desc}' {branches}\n"
  > EOF

  $ hg init a
  $ cd a

  $ echo a > a
  $ hg ci -Am A
  adding a

  $ hg branch branch1
  marked working directory as branch branch1
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m 'branch1'

  $ echo b > b
  $ hg ci -Am B
  adding b

  $ hg up -q 0

  $ hg branch branch2
  marked working directory as branch branch2
  $ hg ci -m 'branch2'

  $ echo c > C
  $ hg ci -Am C
  adding C

  $ hg up -q 2

  $ hg branch -f branch2
  marked working directory as branch branch2
  $ echo d > d
  $ hg ci -Am D
  adding d
  created new head

  $ echo e > e
  $ hg ci -Am E
  adding e

  $ hg update default
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved

  $ hg branch branch3
  marked working directory as branch branch3
  $ hg ci -m 'branch3'

  $ echo f > f
  $ hg ci -Am F
  adding f

  $ cd ..


Rebase part of branch2 (5-6) onto branch3 (8):

  $ hg clone -q -u . a a1
  $ cd a1

  $ hg tglog
  @  8: 'F' branch3
  |
  o  7: 'branch3' branch3
  |
  | o  6: 'E' branch2
  | |
  | o  5: 'D' branch2
  | |
  | | o  4: 'C' branch2
  | | |
  +---o  3: 'branch2' branch2
  | |
  | o  2: 'B' branch1
  | |
  | o  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ hg branches
  branch3                        8:4666b71e8e32
  branch2                        6:5097051d331d
  branch1                        2:0a03079c47fd (inactive)
  default                        0:1994f17a630e (inactive)

  $ hg theads
  8: 'F' branch3
  6: 'E' branch2
  4: 'C' branch2
  2: 'B' branch1
  0: 'A' 

  $ hg rebase -s 5 -d 8
  rebasing 5:635859577d0b "D"
  rebasing 6:5097051d331d "E"
  saved backup bundle to $TESTTMP/a1/.hg/strip-backup/635859577d0b-89160bff-rebase.hg

  $ hg branches
  branch3                        8:466cdfb14b62
  branch2                        4:e4fdb121d036
  branch1                        2:0a03079c47fd
  default                        0:1994f17a630e (inactive)

  $ hg theads
  8: 'E' branch3
  4: 'C' branch2
  2: 'B' branch1
  0: 'A' 

  $ hg tglog
  o  8: 'E' branch3
  |
  o  7: 'D' branch3
  |
  @  6: 'F' branch3
  |
  o  5: 'branch3' branch3
  |
  | o  4: 'C' branch2
  | |
  | o  3: 'branch2' branch2
  |/
  | o  2: 'B' branch1
  | |
  | o  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ cd ..


Rebase head of branch3 (8) onto branch2 (6):

  $ hg clone -q -u . a a2
  $ cd a2

  $ hg tglog
  @  8: 'F' branch3
  |
  o  7: 'branch3' branch3
  |
  | o  6: 'E' branch2
  | |
  | o  5: 'D' branch2
  | |
  | | o  4: 'C' branch2
  | | |
  +---o  3: 'branch2' branch2
  | |
  | o  2: 'B' branch1
  | |
  | o  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ hg rebase -s 8 -d 6
  rebasing 8:4666b71e8e32 "F" (tip)
  saved backup bundle to $TESTTMP/a2/.hg/strip-backup/4666b71e8e32-fc1c4e96-rebase.hg

  $ hg branches
  branch2                        8:6b4bdc1b5ac0
  branch3                        7:653b9feb4616
  branch1                        2:0a03079c47fd (inactive)
  default                        0:1994f17a630e (inactive)

  $ hg theads
  8: 'F' branch2
  7: 'branch3' branch3
  4: 'C' branch2
  2: 'B' branch1
  0: 'A' 

  $ hg tglog
  @  8: 'F' branch2
  |
  | o  7: 'branch3' branch3
  | |
  o |  6: 'E' branch2
  | |
  o |  5: 'D' branch2
  | |
  | | o  4: 'C' branch2
  | | |
  | | o  3: 'branch2' branch2
  | |/
  o |  2: 'B' branch1
  | |
  o |  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ hg verify -q

  $ cd ..


Rebase entire branch3 (7-8) onto branch2 (6):

  $ hg clone -q -u . a a3
  $ cd a3

  $ hg tglog
  @  8: 'F' branch3
  |
  o  7: 'branch3' branch3
  |
  | o  6: 'E' branch2
  | |
  | o  5: 'D' branch2
  | |
  | | o  4: 'C' branch2
  | | |
  +---o  3: 'branch2' branch2
  | |
  | o  2: 'B' branch1
  | |
  | o  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ hg rebase -s 7 -d 6
  rebasing 7:653b9feb4616 "branch3"
  note: rebase of 7:653b9feb4616 created no changes to commit
  rebasing 8:4666b71e8e32 "F" (tip)
  saved backup bundle to $TESTTMP/a3/.hg/strip-backup/653b9feb4616-3c88de16-rebase.hg

  $ hg branches
  branch2                        7:6b4bdc1b5ac0
  branch1                        2:0a03079c47fd (inactive)
  default                        0:1994f17a630e (inactive)

  $ hg theads
  7: 'F' branch2
  4: 'C' branch2
  2: 'B' branch1
  0: 'A' 

  $ hg tglog
  @  7: 'F' branch2
  |
  o  6: 'E' branch2
  |
  o  5: 'D' branch2
  |
  | o  4: 'C' branch2
  | |
  | o  3: 'branch2' branch2
  | |
  o |  2: 'B' branch1
  | |
  o |  1: 'branch1' branch1
  |/
  o  0: 'A'
  
  $ hg verify -q

Stripping multiple branches in one go bypasses the fast-case code to
update the branch cache.

  $ hg strip 2
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/a3/.hg/strip-backup/0a03079c47fd-11b7c407-backup.hg

  $ hg tglog
  o  3: 'C' branch2
  |
  o  2: 'branch2' branch2
  |
  | @  1: 'branch1' branch1
  |/
  o  0: 'A'
  

  $ hg branches
  branch2                        3:e4fdb121d036
  branch1                        1:63379ac49655
  default                        0:1994f17a630e (inactive)

  $ hg theads
  3: 'C' branch2
  1: 'branch1' branch1
  0: 'A' 

Fast path branchcache code should not be invoked if branches stripped is not
the same as branches remaining.

  $ hg init b
  $ cd b

  $ hg branch branch1
  marked working directory as branch branch1
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m 'branch1'

  $ hg branch branch2
  marked working directory as branch branch2
  $ hg ci -m 'branch2'

  $ hg branch -f branch1
  marked working directory as branch branch1

  $ echo a > A
  $ hg ci -Am A
  adding A
  created new head

  $ hg tglog
  @  2: 'A' branch1
  |
  o  1: 'branch2' branch2
  |
  o  0: 'branch1' branch1
  

  $ hg theads
  2: 'A' branch1
  1: 'branch2' branch2

  $ hg strip 2
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/a3/b/.hg/strip-backup/a5b4b27ed7b4-a3b6984e-backup.hg

  $ hg theads
  1: 'branch2' branch2
  0: 'branch1' branch1


Make sure requesting to strip a revision already stripped does not confuse things.
Try both orders.

  $ cd ..

  $ hg init c
  $ cd c

  $ echo a > a
  $ hg ci -Am A
  adding a
  $ echo b > b
  $ hg ci -Am B
  adding b
  $ echo c > c
  $ hg ci -Am C
  adding c
  $ echo d > d
  $ hg ci -Am D
  adding d
  $ echo e > e
  $ hg ci -Am E
  adding e

  $ hg tglog
  @  4: 'E'
  |
  o  3: 'D'
  |
  o  2: 'C'
  |
  o  1: 'B'
  |
  o  0: 'A'
  

  $ hg strip 3 4
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/a3/c/.hg/strip-backup/67a385d4e6f2-b9243789-backup.hg

  $ hg theads
  2: 'C' 

  $ hg strip 2 1
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/a3/c/.hg/strip-backup/6c81ed0049f8-a687065f-backup.hg

  $ hg theads
  0: 'A' 

Make sure rebase does not break for phase/filter related reason
----------------------------------------------------------------
(issue3858)

  $ cd ..

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > logtemplate={rev} {desc} {phase}\n
  > EOF


  $ hg init c4
  $ cd c4

  $ echo a > a
  $ hg ci -Am A
  adding a
  $ echo b > b
  $ hg ci -Am B
  adding b
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c > c
  $ hg ci -Am C
  adding c
  created new head
  $ hg up 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m d
  $ hg up 2
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo e > e
  $ hg ci -Am E
  adding e
  created new head
  $ hg merge 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m F
  $ hg up 3
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo g > g
  $ hg ci -Am G
  adding g
  created new head
  $ echo h > h
  $ hg ci -Am H
  adding h
  $ hg up 5
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo i > i
  $ hg ci -Am I
  adding i

Turn most changeset public

  $ hg ph -p 7

  $ hg heads
  8 I draft
  7 H public
  $ hg log -G
  @  8 I draft
  |
  | o  7 H public
  | |
  | o  6 G public
  | |
  o |  5 F draft
  |\|
  o |  4 E draft
  | |
  | o  3 d public
  |/|
  o |  2 C public
  | |
  | o  1 B public
  |/
  o  0 A public
  

  $ cat > $TESTTMP/checkeditform.sh <<EOF
  > env | grep HGEDITFORM
  > true
  > EOF
  $ HGEDITOR="sh $TESTTMP/checkeditform.sh" hg rebase --dest 7 --source 5 -e
  rebasing 5:361a99976cc9 "F"
  HGEDITFORM=rebase.merge
  rebasing 8:326cfedc031c "I" (tip)
  HGEDITFORM=rebase.normal
  saved backup bundle to $TESTTMP/a3/c4/.hg/strip-backup/361a99976cc9-35e980d0-rebase.hg