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
$ hg init repo
$ cd repo
$ touch foo
$ hg add foo
$ for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
> echo "foo-$i" >> foo
> hg ci -m "foo-$i"
> done
$ for out in "%nof%N" "%%%H" "%b-%R" "%h" "%r" "%m"; do
> echo
> echo "# foo-$out.patch"
> hg export -v -o "foo-$out.patch" 2:tip
> done
# foo-%nof%N.patch
exporting patches:
foo-01of10.patch
foo-02of10.patch
foo-03of10.patch
foo-04of10.patch
foo-05of10.patch
foo-06of10.patch
foo-07of10.patch
foo-08of10.patch
foo-09of10.patch
foo-10of10.patch
# foo-%%%H.patch
exporting patches:
foo-%617188a1c80f869a7b66c85134da88a6fb145f67.patch
foo-%dd41a5ff707a5225204105611ba49cc5c229d55f.patch
foo-%f95a5410f8664b6e1490a4af654e4b7d41a7b321.patch
foo-%4346bcfde53b4d9042489078bcfa9c3e28201db2.patch
foo-%afda8c3a009cc99449a05ad8aa4655648c4ecd34.patch
foo-%35284ce2b6b99c9d2ac66268fe99e68e1974e1aa.patch
foo-%9688c41894e6931305fa7165a37f6568050b4e9b.patch
foo-%747d3c68f8ec44bb35816bfcd59aeb50b9654c2f.patch
foo-%5f17a83f5fbd9414006a5e563eab4c8a00729efd.patch
foo-%f3acbafac161ec68f1598af38f794f28847ca5d3.patch
# foo-%b-%R.patch
exporting patches:
foo-repo-2.patch
foo-repo-3.patch
foo-repo-4.patch
foo-repo-5.patch
foo-repo-6.patch
foo-repo-7.patch
foo-repo-8.patch
foo-repo-9.patch
foo-repo-10.patch
foo-repo-11.patch
# foo-%h.patch
exporting patches:
foo-617188a1c80f.patch
foo-dd41a5ff707a.patch
foo-f95a5410f866.patch
foo-4346bcfde53b.patch
foo-afda8c3a009c.patch
foo-35284ce2b6b9.patch
foo-9688c41894e6.patch
foo-747d3c68f8ec.patch
foo-5f17a83f5fbd.patch
foo-f3acbafac161.patch
# foo-%r.patch
exporting patches:
foo-02.patch
foo-03.patch
foo-04.patch
foo-05.patch
foo-06.patch
foo-07.patch
foo-08.patch
foo-09.patch
foo-10.patch
foo-11.patch
# foo-%m.patch
exporting patches:
foo-foo_2.patch
foo-foo_3.patch
foo-foo_4.patch
foo-foo_5.patch
foo-foo_6.patch
foo-foo_7.patch
foo-foo_8.patch
foo-foo_9.patch
foo-foo_10.patch
foo-foo_11.patch
Doing it again clobbers the files rather than appending:
$ hg export -v -o "foo-%m.patch" 2:3
exporting patches:
foo-foo_2.patch
foo-foo_3.patch
$ grep HG foo-foo_2.patch | wc -l
\s*1 (re)
$ grep HG foo-foo_3.patch | wc -l
\s*1 (re)
Using bookmarks:
$ hg book -f -r 9 @
$ hg book -f -r 11 test
$ hg export -B test
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID 5f17a83f5fbd9414006a5e563eab4c8a00729efd
# Parent 747d3c68f8ec44bb35816bfcd59aeb50b9654c2f
foo-10
diff -r 747d3c68f8ec -r 5f17a83f5fbd foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -8,3 +8,4 @@
foo-7
foo-8
foo-9
+foo-10
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID f3acbafac161ec68f1598af38f794f28847ca5d3
# Parent 5f17a83f5fbd9414006a5e563eab4c8a00729efd
foo-11
diff -r 5f17a83f5fbd -r f3acbafac161 foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -9,3 +9,4 @@
foo-8
foo-9
foo-10
+foo-11
Exporting 4 changesets to a file:
$ hg export -o export_internal 1 2 3 4
$ grep HG export_internal | wc -l
\s*4 (re)
Doing it again clobbers the file rather than appending:
$ hg export -o export_internal 1 2 3 4
$ grep HG export_internal | wc -l
\s*4 (re)
Exporting 4 changesets to stdout:
$ hg export 1 2 3 4 | grep HG | wc -l
\s*4 (re)
Exporting revision -2 to a file:
$ hg export -- -2
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID 5f17a83f5fbd9414006a5e563eab4c8a00729efd
# Parent 747d3c68f8ec44bb35816bfcd59aeb50b9654c2f
foo-10
diff -r 747d3c68f8ec -r 5f17a83f5fbd foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -8,3 +8,4 @@
foo-7
foo-8
foo-9
+foo-10
Exporting wdir revision:
$ echo "foo-wdir" >> foo
$ hg export 'wdir()'
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID ffffffffffffffffffffffffffffffffffffffff
# Parent f3acbafac161ec68f1598af38f794f28847ca5d3
diff -r f3acbafac161 foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -10,3 +10,4 @@
foo-9
foo-10
foo-11
+foo-wdir
$ hg revert -q foo
Templated output to stdout:
$ hg export -Tjson 0
[
{
"branch": "default",
"date": [0, 0],
"desc": "foo-0",
"diff": "diff -r 000000000000 -r 871558de6af2 foo\n--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\n+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n@@ -0,0 +1,1 @@\n+foo-0\n",
"node": "871558de6af2e8c244222f8eea69b782c94ce3df",
"parents": [],
"user": "test"
}
]
Templated output to single file:
$ hg export -Tjson 0:1 -o out.json
$ cat out.json
[
{
"branch": "default",
"date": [0, 0],
"desc": "foo-0",
"diff": "diff -r 000000000000 -r 871558de6af2 foo\n--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\n+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n@@ -0,0 +1,1 @@\n+foo-0\n",
"node": "871558de6af2e8c244222f8eea69b782c94ce3df",
"parents": [],
"user": "test"
},
{
"branch": "default",
"date": [0, 0],
"desc": "foo-1",
"diff": "diff -r 871558de6af2 -r d1c9656e973c foo\n--- a/foo\tThu Jan 01 00:00:00 1970 +0000\n+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n@@ -1,1 +1,2 @@\n foo-0\n+foo-1\n",
"node": "d1c9656e973cfb5aebd5499bbd2cb350e3b12266",
"parents": ["871558de6af2e8c244222f8eea69b782c94ce3df"],
"user": "test"
}
]
Templated output to multiple files:
$ hg export -Tjson 0:1 -o 'out-{rev}.json'
$ cat out-0.json
[
{
"branch": "default",
"date": [0, 0],
"desc": "foo-0",
"diff": "diff -r 000000000000 -r 871558de6af2 foo\n--- /dev/null\tThu Jan 01 00:00:00 1970 +0000\n+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n@@ -0,0 +1,1 @@\n+foo-0\n",
"node": "871558de6af2e8c244222f8eea69b782c94ce3df",
"parents": [],
"user": "test"
}
]
$ cat out-1.json
[
{
"branch": "default",
"date": [0, 0],
"desc": "foo-1",
"diff": "diff -r 871558de6af2 -r d1c9656e973c foo\n--- a/foo\tThu Jan 01 00:00:00 1970 +0000\n+++ b/foo\tThu Jan 01 00:00:00 1970 +0000\n@@ -1,1 +1,2 @@\n foo-0\n+foo-1\n",
"node": "d1c9656e973cfb5aebd5499bbd2cb350e3b12266",
"parents": ["871558de6af2e8c244222f8eea69b782c94ce3df"],
"user": "test"
}
]
Template keywrods:
$ hg export 0 -T '# {node|shortest}\n\n{diff}'
# 8715
diff -r 000000000000 -r 871558de6af2 foo
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -0,0 +1,1 @@
+foo-0
No filename should be printed if stdout is specified explicitly:
$ hg export -v 1 -o -
exporting patch:
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID d1c9656e973cfb5aebd5499bbd2cb350e3b12266
# Parent 871558de6af2e8c244222f8eea69b782c94ce3df
foo-1
diff -r 871558de6af2 -r d1c9656e973c foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,2 @@
foo-0
+foo-1
Checking if only alphanumeric characters are used in the file name (%m option):
$ echo "line" >> foo
$ hg commit -m " !\"#$%&(,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]"'^'"_\`abcdefghijklmnopqrstuvwxyz{|}~"
$ hg export -v -o %m.patch tip
exporting patch:
___________0123456789_______ABCDEFGHIJKLMNOPQRSTUVWXYZ______abcdefghijklmnopqrstuvwxyz____.patch
Template fragments in file name:
$ hg export -v -o '{node|shortest}.patch' tip
exporting patch:
197e.patch
Backslash should be preserved because it is a directory separator on Windows:
$ mkdir out
$ hg export -v -o 'out\{node|shortest}.patch' tip
exporting patch:
out\197e.patch
Still backslash is taken as an escape character in inner template strings:
$ hg export -v -o '{"out\{foo}.patch"}' tip
exporting patch:
out{foo}.patch
Invalid pattern in file name:
$ hg export -o '%x.patch' tip
abort: invalid format spec '%x' in output filename
[255]
$ hg export -o '%' tip
abort: incomplete format spec in output filename
[255]
$ hg export -o '%{"foo"}' tip
abort: incomplete format spec in output filename
[255]
$ hg export -o '%m{' tip
hg: parse error at 3: unterminated template expansion
(%m{
^ here)
[10]
$ hg export -o '%\' tip
abort: invalid format spec '%\' in output filename
[255]
$ hg export -o '\%' tip
abort: incomplete format spec in output filename
[255]
Catch exporting unknown revisions (especially empty revsets, see issue3353)
$ hg export
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID 197ecd81a57f760b54f34a58817ad5b04991fa47
# Parent f3acbafac161ec68f1598af38f794f28847ca5d3
!"#$%&(,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
diff -r f3acbafac161 -r 197ecd81a57f foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -10,3 +10,4 @@
foo-9
foo-10
foo-11
+line
$ hg export ""
hg: parse error: empty query
[10]
$ hg export 999
abort: unknown revision '999'
[255]
$ hg export "not all()"
abort: export requires at least one changeset
[10]
Check for color output
$ cat <<EOF >> $HGRCPATH
> [color]
> mode = ansi
> [extensions]
> color =
> EOF
$ hg export --color always --nodates tip
# HG changeset patch
# User test
# Date 0 0
# Thu Jan 01 00:00:00 1970 +0000
# Node ID * (glob)
# Parent * (glob)
!"#$%&(,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
\x1b[0;1mdiff -r f3acbafac161 -r 197ecd81a57f foo\x1b[0m (esc)
\x1b[0;31;1m--- a/foo\x1b[0m (esc)
\x1b[0;32;1m+++ b/foo\x1b[0m (esc)
\x1b[0;35m@@ -10,3 +10,4 @@\x1b[0m (esc)
foo-9
foo-10
foo-11
\x1b[0;32m+line\x1b[0m (esc)
$ cd ..