hgwebdir: avoid systematic full garbage collection
Forcing a systematic full garbage collection upon each request
can serioulsy harm performance. This is reported as
https://bz.mercurial-scm.org/show_bug.cgi?id=6075
With this change we're performing the full collection according
to a new setting, `experimental.web.full-garbage-collection-rate`.
The default value is 1, which doesn't change the behavior and will
allow us to test on real use cases. If the value is 0, no full garbage
collection occurs.
Regardless of the value of the setting, a partial garbage collection
still occurs upon each request (not attempting to collect objects from
the oldest generation). This should be enough to take care of
reference cycles that have been created by the last request
(assessment of this requires changing the setting, not to be 1).
In my experience chasing memory leaks in Mercurial servers,
the full collection never reclaimed any memory, but this is with
Python 3 and biased towards small repositories.
On the other hand, as explained in the Python developer docs [1],
frequent full collections are very harmful in terms of performance if
lots of objects survive the collection, and hence stay in the
oldest generation. Note that `gc.collect()` is indeed trying to
collect the oldest generation [2]. This happens usually in two cases:
- unwanted lingering objects (i.e., an actual memory leak that
the GC cannot do anything about). Sadly, we have lots of those
these days.
- desireable long-term objects, typically in caches (not inner caches
carried by repositories, which should be collected with them). This
is a subject of interest for the Heptapod project.
In short, the flat rate that this change still permits is
probably a bad idea in most cases, and the default value can
be tweaked later on (or even be set to 0) according to experiments
in the wild.
The test is inspired from test-hgwebdir-paths.py
[1] https://devguide.python.org/garbage_collector/#collecting-the-oldest-generation
[2] https://docs.python.org/3/library/gc.html#gc.collect
Differential Revision: https://phab.mercurial-scm.org/D11204
$ cat <<EOF >> $HGRCPATH
> [ui]
> commitsubrepos = Yes
> [extensions]
> mq =
> record =
> [diff]
> nodates = 1
> EOF
$ stdin=`pwd`/stdin.tmp
fn to create new repository w/dirty subrepo, and cd into it
$ mkrepo() {
> hg init $1
> cd $1
> hg qinit
> }
fn to create dirty subrepo
$ mksubrepo() {
> hg init $1
> cd $1
> echo a > a
> hg add
> cd ..
> }
$ testadd() {
> cat - > "$stdin"
> mksubrepo sub
> echo sub = sub >> .hgsub
> hg add .hgsub
> echo % abort when adding .hgsub w/dirty subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> echo [$?]
> hg -R sub ci -m0sub
> echo % update substate when adding .hgsub w/clean updated subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> hg debugsub
> }
$ testmod() {
> cat - > "$stdin"
> mksubrepo sub2
> echo sub2 = sub2 >> .hgsub
> echo % abort when modifying .hgsub w/dirty subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> echo [$?]
> hg -R sub2 ci -m0sub2
> echo % update substate when modifying .hgsub w/clean updated subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> hg debugsub
> }
$ testrm1() {
> cat - > "$stdin"
> mksubrepo sub3
> echo sub3 = sub3 >> .hgsub
> hg ci -Aqmsub3
> $EXTRA
> echo b >> sub3/a
> hg rm .hgsub
> echo % update substate when removing .hgsub w/dirty subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> echo % debugsub should be empty
> hg debugsub
> }
$ testrm2() {
> cat - > "$stdin"
> mksubrepo sub4
> echo sub4 = sub4 >> .hgsub
> hg ci -Aqmsub4
> $EXTRA
> hg rm .hgsub
> echo % update substate when removing .hgsub w/clean updated subrepo
> hg status -S
> echo '%' $*
> cat "$stdin" | hg $*
> echo % debugsub should be empty
> hg debugsub
> }
handle subrepos safely on qnew
$ mkrepo repo-2499-qnew
$ testadd qnew -X path:no-effect -m0 0.diff
adding a
% abort when adding .hgsub w/dirty subrepo
A .hgsub
A sub/a
% qnew -X path:no-effect -m0 0.diff
abort: uncommitted changes in subrepository "sub"
[255]
% update substate when adding .hgsub w/clean updated subrepo
A .hgsub
A sub/a
% qnew -X path:no-effect -m0 0.diff
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
$ testmod qnew --cwd .. -R repo-2499-qnew -X path:no-effect -m1 1.diff
adding a
% abort when modifying .hgsub w/dirty subrepo
M .hgsub
A sub2/a
% qnew --cwd .. -R repo-2499-qnew -X path:no-effect -m1 1.diff
abort: uncommitted changes in subrepository "sub2"
[255]
% update substate when modifying .hgsub w/clean updated subrepo
M .hgsub
A sub2/a
% qnew --cwd .. -R repo-2499-qnew -X path:no-effect -m1 1.diff
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
path sub2
source sub2
revision 1f94c7611cc6b74f5a17b16121a1170d44776845
$ hg qpop -qa
patch queue now empty
$ testrm1 qnew -m2 2.diff
adding a
% update substate when removing .hgsub w/dirty subrepo
M sub3/a
R .hgsub
% qnew -m2 2.diff
% debugsub should be empty
$ hg qpop -qa
patch queue now empty
$ testrm2 qnew -m3 3.diff
adding a
% update substate when removing .hgsub w/clean updated subrepo
R .hgsub
% qnew -m3 3.diff
% debugsub should be empty
$ cd ..
handle subrepos safely on qrefresh
$ mkrepo repo-2499-qrefresh
$ hg qnew -m0 0.diff
$ testadd qrefresh
adding a
% abort when adding .hgsub w/dirty subrepo
A .hgsub
A sub/a
% qrefresh
abort: uncommitted changes in subrepository "sub"
[255]
% update substate when adding .hgsub w/clean updated subrepo
A .hgsub
A sub/a
% qrefresh
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
$ hg qnew -m1 1.diff
$ testmod qrefresh
adding a
% abort when modifying .hgsub w/dirty subrepo
M .hgsub
A sub2/a
% qrefresh
abort: uncommitted changes in subrepository "sub2"
[255]
% update substate when modifying .hgsub w/clean updated subrepo
M .hgsub
A sub2/a
% qrefresh
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
path sub2
source sub2
revision 1f94c7611cc6b74f5a17b16121a1170d44776845
$ hg qpop -qa
patch queue now empty
$ EXTRA='hg qnew -m2 2.diff'
$ testrm1 qrefresh
adding a
% update substate when removing .hgsub w/dirty subrepo
M sub3/a
R .hgsub
% qrefresh
% debugsub should be empty
$ hg qpop -qa
patch queue now empty
$ EXTRA='hg qnew -m3 3.diff'
$ testrm2 qrefresh
adding a
% update substate when removing .hgsub w/clean updated subrepo
R .hgsub
% qrefresh
% debugsub should be empty
$ EXTRA=
$ cd ..
handle subrepos safely on qpush/qpop
(and we cannot qpop / qpush with a modified subrepo)
$ mkrepo repo-2499-qpush
$ mksubrepo sub
adding a
$ hg -R sub ci -m0sub
$ echo sub = sub > .hgsub
$ hg add .hgsub
$ hg commit -m0
$ hg debugsub
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
$ echo foo > ./sub/a
$ hg -R sub commit -m foo
$ hg commit -m1
$ hg qimport -r "0:tip"
$ hg -R sub id --id
aa037b301eba
qpop
$ hg -R sub update 0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg qpop
abort: local changed subrepos found, qrefresh first
[255]
$ hg revert sub
reverting subrepo sub
adding sub/a
$ hg qpop
popping 1
now at: 0
$ hg status -AS
C .hgsub
C .hgsubstate
C sub/a
$ hg -R sub id --id
b2fdb12cd82b
qpush
$ hg -R sub update 0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg qpush
abort: local changed subrepos found, qrefresh first
[255]
$ hg revert sub
reverting subrepo sub
adding sub/a
$ hg qpush
applying 1
subrepository sub diverged (local revision: b2fdb12cd82b, remote revision: aa037b301eba)
you can (m)erge, keep (l)ocal or keep (r)emote.
what do you want to do? m
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
now at: 1
$ hg status -AS
C .hgsub
C .hgsubstate
C sub/a
$ hg -R sub id --id
aa037b301eba
$ cd ..
handle subrepos safely on qrecord
$ mkrepo repo-2499-qrecord
$ testadd qrecord --config ui.interactive=1 -m0 0.diff <<EOF
> y
> y
> EOF
adding a
% abort when adding .hgsub w/dirty subrepo
A .hgsub
A sub/a
% qrecord --config ui.interactive=1 -m0 0.diff
abort: uncommitted changes in subrepository "sub"
[255]
% update substate when adding .hgsub w/clean updated subrepo
A .hgsub
A sub/a
% qrecord --config ui.interactive=1 -m0 0.diff
diff --git a/.hgsub b/.hgsub
new file mode 100644
examine changes to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
@@ -0,0 +1,1 @@
+sub = sub
record this change to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
warning: subrepo spec file '.hgsub' not found
warning: subrepo spec file '.hgsub' not found
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
$ testmod qrecord --config ui.interactive=1 -m1 1.diff <<EOF
> y
> y
> EOF
adding a
% abort when modifying .hgsub w/dirty subrepo
M .hgsub
A sub2/a
% qrecord --config ui.interactive=1 -m1 1.diff
abort: uncommitted changes in subrepository "sub2"
[255]
% update substate when modifying .hgsub w/clean updated subrepo
M .hgsub
A sub2/a
% qrecord --config ui.interactive=1 -m1 1.diff
diff --git a/.hgsub b/.hgsub
1 hunks, 1 lines changed
examine changes to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
@@ -1,1 +1,2 @@
sub = sub
+sub2 = sub2
record this change to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
path sub
source sub
revision b2fdb12cd82b021c3b7053d67802e77b6eeaee31
path sub2
source sub2
revision 1f94c7611cc6b74f5a17b16121a1170d44776845
$ hg qpop -qa
patch queue now empty
$ testrm1 qrecord --config ui.interactive=1 -m2 2.diff <<EOF
> y
> y
> EOF
adding a
% update substate when removing .hgsub w/dirty subrepo
M sub3/a
R .hgsub
% qrecord --config ui.interactive=1 -m2 2.diff
diff --git a/.hgsub b/.hgsub
deleted file mode 100644
examine changes to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
% debugsub should be empty
$ hg qpop -qa
patch queue now empty
$ testrm2 qrecord --config ui.interactive=1 -m3 3.diff <<EOF
> y
> y
> EOF
adding a
% update substate when removing .hgsub w/clean updated subrepo
R .hgsub
% qrecord --config ui.interactive=1 -m3 3.diff
diff --git a/.hgsub b/.hgsub
deleted file mode 100644
examine changes to '.hgsub'?
(enter ? for help) [Ynesfdaq?] y
% debugsub should be empty
$ cd ..
correctly handle subrepos with patch queues
$ mkrepo repo-subrepo-with-queue
$ mksubrepo sub
adding a
$ hg -R sub qnew sub0.diff
$ echo sub = sub >> .hgsub
$ hg add .hgsub
$ hg qnew 0.diff
$ cd ..
check whether MQ operations can import updated .hgsubstate correctly
both into 'revision' and 'patch file under .hg/patches':
$ hg init importing-hgsubstate
$ cd importing-hgsubstate
$ echo a > a
$ hg commit -u test -d '0 0' -Am '#0 in parent'
adding a
$ hg init sub
$ echo sa > sub/sa
$ hg -R sub commit -u test -d '0 0' -Am '#0 in sub'
adding sa
$ echo 'sub = sub' > .hgsub
$ touch .hgsubstate
$ hg add .hgsub .hgsubstate
$ hg qnew -u test -d '0 0' import-at-qnew
$ hg -R sub parents --template '{node} sub\n'
b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
$ cat .hgsubstate
b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
$ hg diff -c tip
diff -r f499373e340c -r f69e96d86e75 .hgsub
--- /dev/null
+++ b/.hgsub
@@ -0,0 +1,1 @@
+sub = sub
diff -r f499373e340c -r f69e96d86e75 .hgsubstate
--- /dev/null
+++ b/.hgsubstate
@@ -0,0 +1,1 @@
+b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
$ cat .hg/patches/import-at-qnew
# HG changeset patch
# User test
# Date 0 0
# Parent f499373e340cdca5d01dee904aeb42dd2a325e71
diff -r f499373e340c -r f69e96d86e75 .hgsub
--- /dev/null
+++ b/.hgsub
@@ -0,0 +1,1 @@
+sub = sub
diff -r f499373e340c -r f69e96d86e75 .hgsubstate
--- /dev/null
+++ b/.hgsubstate
@@ -0,0 +1,1 @@
+b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
$ hg parents --template '{node}\n'
f69e96d86e75a6d4fd88285dc9697acb23951041
$ hg parents --template '{files}\n'
.hgsub .hgsubstate
check also whether qnew not including ".hgsubstate" explicitly causes
as same result (in node hash) as one including it.
$ hg qpop -a -q
patch queue now empty
$ hg qdelete import-at-qnew
$ echo 'sub = sub' > .hgsub
$ hg add .hgsub
$ rm -f .hgsubstate
$ hg qnew -u test -d '0 0' import-at-qnew
$ hg parents --template '{node}\n'
f69e96d86e75a6d4fd88285dc9697acb23951041
$ hg parents --template '{files}\n'
.hgsub .hgsubstate
check whether qrefresh imports updated .hgsubstate correctly
$ hg qpop
popping import-at-qnew
patch queue now empty
$ hg qpush
applying import-at-qnew
now at: import-at-qnew
$ hg parents --template '{files}\n'
.hgsub .hgsubstate
$ hg qnew import-at-qrefresh
$ echo sb > sub/sb
$ hg -R sub commit -u test -d '0 0' -Am '#1 in sub'
adding sb
$ hg qrefresh -u test -d '0 0'
$ hg -R sub parents --template '{node} sub\n'
88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ cat .hgsubstate
88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg diff -c tip
diff -r 05b056bb9c8c -r d987bec230f4 .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ cat .hg/patches/import-at-qrefresh
# HG changeset patch
# User test
# Date 0 0
# Parent 05b056bb9c8c05ff15258b84fd42ab3527271033
diff -r 05b056bb9c8c .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg parents --template '{files}\n'
.hgsubstate
$ hg qrefresh -u test -d '0 0'
$ cat .hgsubstate
88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg diff -c tip
diff -r 05b056bb9c8c -r d987bec230f4 .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ cat .hg/patches/import-at-qrefresh
# HG changeset patch
# User test
# Date 0 0
# Parent 05b056bb9c8c05ff15258b84fd42ab3527271033
diff -r 05b056bb9c8c .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg parents --template '{files}\n'
.hgsubstate
$ hg update -C tip
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg qpop -a
popping import-at-qrefresh
popping import-at-qnew
patch queue now empty
$ hg -R sub update -C 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo 'sub = sub' > .hgsub
$ hg commit -Am '#1 in parent'
adding .hgsub
$ hg -R sub update -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg commit -Am '#2 in parent (but will be rolled back soon)'
$ hg rollback
repository tip rolled back to revision 1 (undo commit)
working directory now based on revision 1
$ hg status
M .hgsubstate
$ hg qnew -u test -d '0 0' checkstate-at-qnew
$ hg -R sub parents --template '{node} sub\n'
88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ cat .hgsubstate
88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg diff -c tip
diff -r 4d91eb2fa1d1 -r 1259c112d884 .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ cat .hg/patches/checkstate-at-qnew
# HG changeset patch
# User test
# Date 0 0
# Parent 4d91eb2fa1d1b22ec513347b9cd06f6b49d470fa
diff -r 4d91eb2fa1d1 -r 1259c112d884 .hgsubstate
--- a/.hgsubstate
+++ b/.hgsubstate
@@ -1,1 +1,1 @@
-b6f6e9c41f3dfd374a6d2ed4535c87951cf979cf sub
+88ac1bef5ed43b689d1d200b59886b675dec474b sub
$ hg parents --template '{files}\n'
.hgsubstate
check whether qrefresh not including ".hgsubstate" explicitly causes
as same result (in node hash) as one including it.
$ hg update -C -q 0
$ hg qpop -a -q
patch queue now empty
$ hg qnew -u test -d '0 0' add-hgsub-at-qrefresh
$ echo 'sub = sub' > .hgsub
$ echo > .hgsubstate
$ hg add .hgsub .hgsubstate
$ hg qrefresh -u test -d '0 0'
$ hg parents --template '{node}\n'
7c48c35501aae6770ed9c2517014628615821a8e
$ hg parents --template '{files}\n'
.hgsub .hgsubstate
$ hg qpop -a -q
patch queue now empty
$ hg qdelete add-hgsub-at-qrefresh
$ hg qnew -u test -d '0 0' add-hgsub-at-qrefresh
$ echo 'sub = sub' > .hgsub
$ hg add .hgsub
$ rm -f .hgsubstate
$ hg qrefresh -u test -d '0 0'
$ hg parents --template '{node}\n'
7c48c35501aae6770ed9c2517014628615821a8e
$ hg parents --template '{files}\n'
.hgsub .hgsubstate
$ cd ..
$ cd ..