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 > foo
$ hg ci -Am m
adding foo
$ cd ..
$ hg clone t tt
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd tt
$ echo 1.1 > foo
$ hg ci -Am m
$ cd ../t
$ echo 1.2 > foo
$ hg ci -Am m
Should not update to the other topological branch:
$ hg pull -u ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 other heads for branch "default"
$ cd ../tt
Should not update to the other branch:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 other heads for branch "default"
$ HGMERGE=true hg merge
merging foo
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -mm
$ cd ../t
Should work:
$ hg pull -u ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (-1 heads)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Similarity between "hg update" and "hg pull -u" in handling bookmark
====================================================================
Test that updating activates the bookmark, which matches with the
explicit destination of the update.
$ echo 4 >> foo
$ hg commit -m "#4"
$ hg bookmark active-after-pull
$ cd ../tt
(1) activating by --rev BOOKMARK
$ hg bookmark -f active-before-pull
$ hg bookmarks
* active-before-pull 3:483b76ad4309
$ hg pull -u -r active-after-pull
pulling from $TESTTMP/t (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
adding remote bookmark active-after-pull
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark active-after-pull)
$ hg parents -q
4:f815b3da6163
$ hg bookmarks
* active-after-pull 4:f815b3da6163
active-before-pull 3:483b76ad4309
(discard pulled changes)
$ hg update -q 483b76ad4309
$ hg rollback -q
(2) activating by URL#BOOKMARK
$ hg bookmark -f active-before-pull
$ hg bookmarks
* active-before-pull 3:483b76ad4309
$ hg pull -u $TESTTMP/t#active-after-pull
pulling from $TESTTMP/t (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
adding remote bookmark active-after-pull
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark active-after-pull)
$ hg parents -q
4:f815b3da6163
$ hg bookmarks
* active-after-pull 4:f815b3da6163
active-before-pull 3:483b76ad4309
(discard pulled changes)
$ hg update -q 483b76ad4309
$ hg rollback -q
Test that updating deactivates current active bookmark, if the
destination of the update is explicitly specified, and it doesn't
match with the name of any exsiting bookmarks.
$ cd ../t
$ hg bookmark -d active-after-pull
$ hg branch bar -q
$ hg commit -m "#5 (bar #1)"
$ cd ../tt
(1) deactivating by --rev REV
$ hg bookmark -f active-before-pull
$ hg bookmarks
* active-before-pull 3:483b76ad4309
$ hg pull -u -r b5e4babfaaa7
pulling from $TESTTMP/t (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark active-before-pull)
$ hg parents -q
5:b5e4babfaaa7
$ hg bookmarks
active-before-pull 3:483b76ad4309
(discard pulled changes)
$ hg update -q 483b76ad4309
$ hg rollback -q
(2) deactivating by --branch BRANCH
$ hg bookmark -f active-before-pull
$ hg bookmarks
* active-before-pull 3:483b76ad4309
$ hg pull -u -b bar
pulling from $TESTTMP/t (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark active-before-pull)
$ hg parents -q
5:b5e4babfaaa7
$ hg bookmarks
active-before-pull 3:483b76ad4309
(discard pulled changes)
$ hg update -q 483b76ad4309
$ hg rollback -q
(3) deactivating by URL#ANOTHER-BRANCH
$ hg bookmark -f active-before-pull
$ hg bookmarks
* active-before-pull 3:483b76ad4309
$ hg pull -u $TESTTMP/t#bar
pulling from $TESTTMP/t (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark active-before-pull)
$ hg parents -q
5:b5e4babfaaa7
$ hg bookmarks
active-before-pull 3:483b76ad4309
$ cd ..