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
#require icasefs
$ hg debugfs | grep 'case-sensitive:'
case-sensitive: no
test file addition with bad case
$ hg init repo1
$ cd repo1
$ echo a > a
$ hg add A
$ hg st
A a
$ hg ci -m adda
$ hg manifest
a
$ cd ..
test case collision on rename (issue750)
$ hg init repo2
$ cd repo2
$ echo a > a
$ hg --debug ci -Am adda
adding a
committing files:
a
committing manifest
committing changelog
updating the branch cache
committed changeset 0:07f4944404050f47db2e5c5071e0e84e7a27bba9
Case-changing renames should work:
$ hg mv a A
$ hg mv A a
$ hg st
addremove after case-changing rename has no effect (issue4590)
$ hg mv a A
$ hg addremove
recording removal of a as rename to A (100% similar)
$ hg revert --all
forgetting A
undeleting a
test changing case of path components
$ mkdir D
$ echo b > D/b
$ hg ci -Am addb D/b
$ hg mv D/b d/b
D/b: not overwriting - file already committed
('hg rename --force' to replace the file by recording a rename)
[1]
$ hg mv D/b d/c
$ hg st
A D/c
R D/b
$ mv D temp
$ mv temp d
$ hg st
A D/c
R D/b
$ hg revert -aq
$ rm d/c
$ echo c > D/c
$ hg add D/c
$ hg st
A D/c
$ hg ci -m addc D/c
$ hg mv d/b d/e
$ hg st
A D/e
R D/b
$ hg revert -aq
$ rm d/e
$ hg mv d/b D/B
$ hg st
A D/B
R D/b
$ cd ..
test case collision between revisions (issue912)
$ hg init repo3
$ cd repo3
$ echo a > a
$ hg ci -Am adda
adding a
$ hg rm a
$ hg ci -Am removea
$ echo A > A
on linux hfs keeps the old case stored, force it
$ mv a aa
$ mv aa A
$ hg ci -Am addA
adding A
used to fail under case insensitive fs
$ hg up -C 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg up -C
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
no clobbering of untracked files with wrong casing
$ hg up -r null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo gold > a
$ hg up
A: untracked file differs
abort: untracked files in working directory differ from files in requested revision
[20]
$ cat a
gold
$ rm a
test that normal file in different case on target context is not
unlinked by largefiles extension.
$ cat >> .hg/hgrc <<EOF
> [extensions]
> largefiles=
> EOF
$ hg update -q -C 1
$ hg status -A
$ echo 'A as largefiles' > A
$ hg add --large A
$ hg commit -m '#3'
created new head
$ hg manifest -r 3
.hglf/A
$ hg manifest -r 0
a
$ hg update -q -C 0
$ hg status -A
C a
$ hg update -q -C 3
$ hg update -q 0
$ hg up -C -r 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv A a
$ hg diff -g > rename.diff
$ hg ci -m 'A -> a'
$ hg up -q '.^'
$ hg import rename.diff -m "import rename A -> a"
applying rename.diff
$ hg st
? rename.diff
$ hg files
a
$ find * | sort
a
rename.diff
$ rm rename.diff
$ cd ..
issue 3342: file in nested directory causes unexpected abort
$ hg init issue3342
$ cd issue3342
$ mkdir -p a/B/c/D
$ echo e > a/B/c/D/e
$ hg add a/B/c/D/e
$ hg ci -m 'add e'
issue 4481: revert across case only renames
$ hg mv a/B/c/D/e a/B/c/d/E
$ hg ci -m "uppercase E"
$ echo 'foo' > a/B/c/D/E
$ hg ci -m 'e content change'
$ hg revert --all -r 0
removing a/B/c/D/E
adding a/B/c/D/e
$ find * | sort
a
a/B
a/B/c
a/B/c/D
a/B/c/D/e
a/B/c/D/e.orig
$ cd ..
issue 3340: mq does not handle case changes correctly
in addition to reported case, 'hg qrefresh' is also tested against
case changes.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init issue3340
$ cd issue3340
$ echo a > mIxEdCaSe
$ hg add mIxEdCaSe
$ hg commit -m '#0'
$ hg rename mIxEdCaSe tmp
$ hg rename tmp MiXeDcAsE
$ hg status -A
A MiXeDcAsE
mIxEdCaSe
R mIxEdCaSe
$ hg qnew changecase
$ hg status -A
C MiXeDcAsE
$ hg qpop -a
popping changecase
patch queue now empty
$ hg qnew refresh-casechange
$ hg status -A
C mIxEdCaSe
$ hg rename mIxEdCaSe tmp
$ hg rename tmp MiXeDcAsE
$ hg status -A
A MiXeDcAsE
mIxEdCaSe
R mIxEdCaSe
$ hg qrefresh
$ hg status -A
C MiXeDcAsE
$ hg qpop -a
popping refresh-casechange
patch queue now empty
$ hg qnew refresh-pattern
$ hg status
$ echo A > A
$ hg add
adding A
$ hg qrefresh a # issue 3271, qrefresh with file handled case wrong
$ hg status # empty status means the qrefresh worked
#if osx
We assume anyone running the tests on a case-insensitive volume on OS
X will be using HFS+. If that's not true, this test will fail.
$ rm A
>>> open(u'a\u200c'.encode('utf-8'), 'w').write('unicode is fun') and None
$ hg status
M A
#endif
$ cd ..