commandserver: add new forking server implemented without using SocketServer
SocketServer.ForkingMixIn of Python 2.x has a couple of issues, such as:
- race condition that leads to 100% CPU usage (Python 2.6)
https://bugs.python.org/
issue21491
- can't wait for children belonging to different process groups (Python 2.6)
- leaves at least one zombie process (Python 2.6, 2.7)
https://bugs.python.org/
issue11109
The first two are critical because we do setpgid(0, 0) in child process to
isolate terminal signals. The last one isn't, but ForkingMixIn seems to be
doing silly. So there are two choices:
a) backport and maintain SocketServer until we can drop support for Python 2.x
b) replace SocketServer by simpler one and eliminate glue codes
I chose (b) because it's great time for getting rid of utterly complicated
SocketServer stuff, and preparing for future move towards prefork service.
New unixforkingservice is implemented loosely based on chg
531f8ef64be6. It
is monolithic but much simpler than SocketServer. unixservicehandler provides
customizing points for chg, and it will be shared with future prefork service.
Old unixservice class is still used by chgserver. It will be removed later.
Thanks to Jun Wu for investigating these issues.
$ hg init t
$ cd t
$ echo 1 > a
$ hg ci -qAm "first"
$ hg cp a b
$ hg mv a c
$ echo 2 >> b
$ echo 2 >> c
$ hg ci -qAm "second"
$ hg co -C 0
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo 0 > a
$ echo 1 >> a
$ hg ci -qAm "other"
$ hg merge --debug
searching for copies back to rev 1
unmatched files in other:
b
c
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a' -> dst: 'b' *
src: 'a' -> dst: 'c' *
checking for directory renames
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: b8bf91eeebbc, local: add3f11052fa+, remote: 17c05bb7fcb6
preserving a for resolve of b
preserving a for resolve of c
removing a
starting 4 threads for background file closing (?)
b: remote moved from a -> m (premerge)
picked tool ':merge' for b (binary False symlink False changedelete False)
merging a and b to b
my b@add3f11052fa+ other b@17c05bb7fcb6 ancestor a@b8bf91eeebbc
premerge successful
c: remote moved from a -> m (premerge)
picked tool ':merge' for c (binary False symlink False changedelete False)
merging a and c to c
my c@add3f11052fa+ other c@17c05bb7fcb6 ancestor a@b8bf91eeebbc
premerge successful
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
file b
$ cat b
0
1
2
file c
$ cat c
0
1
2
Test disabling copy tracing
- first verify copy metadata was kept
$ hg up -qC 2
$ hg rebase --keep -d 1 -b 2 --config extensions.rebase=
rebasing 2:add3f11052fa "other" (tip)
merging b and a to b
merging c and a to c
$ cat b
0
1
2
- next verify copy metadata is lost when disabled
$ hg strip -r . --config extensions.strip=
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
saved backup bundle to $TESTTMP/t/.hg/strip-backup/550bd84c0cd3-fc575957-backup.hg (glob)
$ hg up -qC 2
$ hg rebase --keep -d 1 -b 2 --config extensions.rebase= --config experimental.disablecopytrace=True --config ui.interactive=True << EOF
> c
> EOF
rebasing 2:add3f11052fa "other" (tip)
remote changed a which local deleted
use (c)hanged version, leave (d)eleted, or leave (u)nresolved? c
$ cat b
1
2
$ cd ..
Verify disabling copy tracing still keeps copies from rebase source
$ hg init copydisable
$ cd copydisable
$ touch a
$ hg ci -Aqm 'add a'
$ touch b
$ hg ci -Aqm 'add b, c'
$ hg cp b x
$ echo x >> x
$ hg ci -qm 'copy b->x'
$ hg up -q 1
$ touch z
$ hg ci -Aqm 'add z'
$ hg log -G -T '{rev} {desc}\n'
@ 3 add z
|
| o 2 copy b->x
|/
o 1 add b, c
|
o 0 add a
$ hg rebase -d . -b 2 --config extensions.rebase= --config experimental.disablecopytrace=True
rebasing 2:6adcf8c12e7d "copy b->x"
saved backup bundle to $TESTTMP/copydisable/.hg/strip-backup/6adcf8c12e7d-ce4b3e75-backup.hg (glob)
$ hg up -q 3
$ hg log -f x -T '{rev} {desc}\n'
3 copy b->x
1 add b, c
$ cd ../
Verify we duplicate existing copies, instead of detecting them
$ hg init copydisable3
$ cd copydisable3
$ touch a
$ hg ci -Aqm 'add a'
$ hg cp a b
$ hg ci -Aqm 'copy a->b'
$ hg mv b c
$ hg ci -Aqm 'move b->c'
$ hg up -q 0
$ hg cp a b
$ echo b >> b
$ hg ci -Aqm 'copy a->b (2)'
$ hg log -G -T '{rev} {desc}\n'
@ 3 copy a->b (2)
|
| o 2 move b->c
| |
| o 1 copy a->b
|/
o 0 add a
$ hg rebase -d 2 -s 3 --config extensions.rebase= --config experimental.disablecopytrace=True
rebasing 3:47e1a9e6273b "copy a->b (2)" (tip)
saved backup bundle to $TESTTMP/copydisable3/.hg/strip-backup/47e1a9e6273b-2d099c59-backup.hg (glob)
$ hg log -G -f b
@ changeset: 3:76024fb4b05b
: tag: tip
: user: test
: date: Thu Jan 01 00:00:00 1970 +0000
: summary: copy a->b (2)
:
o changeset: 0:ac82d8b1f7c4
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add a