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
This test tries to exercise the ssh functionality with a dummy script
$ checknewrepo()
> {
> name=$1
> if [ -d "$name"/.hg/store ]; then
> echo store created
> fi
> if [ -f "$name"/.hg/00changelog.i ]; then
> echo 00changelog.i created
> fi
> cat "$name"/.hg/requires
> }
creating 'local'
$ hg init local
$ checknewrepo local
store created
00changelog.i created
dotencode
exp-dirstate-v2 (dirstate-v2 !)
fncache
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
$ echo this > local/foo
$ hg ci --cwd local -A -m "init"
adding foo
test custom revlog chunk cache sizes
$ hg --config format.chunkcachesize=0 log -R local -pv
abort: revlog chunk cache size 0 is not greater than 0
[50]
$ hg --config format.chunkcachesize=1023 log -R local -pv
abort: revlog chunk cache size 1023 is not a power of 2
[50]
$ hg --config format.chunkcachesize=1024 log -R local -pv
changeset: 0:08b9e9f63b32
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files: foo
description:
init
diff -r 000000000000 -r 08b9e9f63b32 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 @@
+this
creating repo with format.usestore=false
$ hg --config format.usestore=false init old
$ checknewrepo old
exp-dirstate-v2 (dirstate-v2 !)
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
testonly-simplestore (reposimplestore !)
sparserevlog
creating repo with format.usefncache=false
$ hg --config format.usefncache=false init old2
$ checknewrepo old2
store created
00changelog.i created
exp-dirstate-v2 (dirstate-v2 !)
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
creating repo with format.dotencode=false
$ hg --config format.dotencode=false init old3
$ checknewrepo old3
store created
00changelog.i created
exp-dirstate-v2 (dirstate-v2 !)
fncache
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
creating repo with format.dotencode=false
$ hg --config format.generaldelta=false --config format.usegeneraldelta=false --config format.sparse-revlog=no init old4
$ checknewrepo old4
store created
00changelog.i created
dotencode
exp-dirstate-v2 (dirstate-v2 !)
fncache
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
store
testonly-simplestore (reposimplestore !)
test failure
$ hg init local
abort: repository local already exists
[255]
init+push to remote2
$ hg init -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote2
$ hg incoming -R remote2 local
comparing with local
changeset: 0:08b9e9f63b32
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: init
$ hg push -R local -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote2
pushing to ssh://user@dummy/remote2
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
clone to remote1
$ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remote1
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
The largefiles extension doesn't crash
$ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remotelf --config extensions.largefiles=
The fsmonitor extension is incompatible with the largefiles extension and has been disabled. (fsmonitor !)
The fsmonitor extension is incompatible with the largefiles extension and has been disabled. (fsmonitor !)
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
init to existing repo
$ hg init -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/remote1
abort: repository remote1 already exists
abort: could not create remote repo
[255]
clone to existing repo
$ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remote1
abort: repository remote1 already exists
abort: could not create remote repo
[255]
output of dummyssh
$ cat dummylog
Got arguments 1:user@dummy 2:hg init remote2
Got arguments 1:user@dummy 2:hg -R remote2 serve --stdio
Got arguments 1:user@dummy 2:hg -R remote2 serve --stdio
Got arguments 1:user@dummy 2:hg init remote1
Got arguments 1:user@dummy 2:hg -R remote1 serve --stdio
Got arguments 1:user@dummy 2:hg init remotelf
Got arguments 1:user@dummy 2:hg -R remotelf serve --stdio
Got arguments 1:user@dummy 2:hg init remote1
Got arguments 1:user@dummy 2:hg init remote1
comparing repositories
$ hg tip -q -R local
0:08b9e9f63b32
$ hg tip -q -R remote1
0:08b9e9f63b32
$ hg tip -q -R remote2
0:08b9e9f63b32
check names for repositories (clashes with URL schemes, special chars)
$ for i in bundle file hg http https old-http ssh static-http "with space"; do
> printf "hg init \"$i\"... "
> hg init "$i"
> test -d "$i" -a -d "$i/.hg" && echo "ok" || echo "failed"
> done
hg init "bundle"... ok
hg init "file"... ok
hg init "hg"... ok
hg init "http"... ok
hg init "https"... ok
hg init "old-http"... ok
hg init "ssh"... ok
hg init "static-http"... ok
hg init "with space"... ok
#if eol-in-paths
/* " " is not a valid name for a directory on Windows */
$ hg init " "
$ test -d " "
$ test -d " /.hg"
#endif
creating 'local/sub/repo'
$ hg init local/sub/repo
$ checknewrepo local/sub/repo
store created
00changelog.i created
dotencode
exp-dirstate-v2 (dirstate-v2 !)
fncache
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
prepare test of init of url configured from paths
$ echo '[paths]' >> $HGRCPATH
$ echo "somewhere = `pwd`/url from paths" >> $HGRCPATH
$ echo "elsewhere = `pwd`/another paths url" >> $HGRCPATH
init should (for consistency with clone) expand the url
$ hg init somewhere
$ checknewrepo "url from paths"
store created
00changelog.i created
dotencode
exp-dirstate-v2 (dirstate-v2 !)
fncache
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
verify that clone also expand urls
$ hg clone somewhere elsewhere
updating to branch default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ checknewrepo "another paths url"
store created
00changelog.i created
dotencode
exp-dirstate-v2 (dirstate-v2 !)
fncache
generaldelta
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
sparserevlog
store
testonly-simplestore (reposimplestore !)
clone bookmarks
$ hg -R local bookmark test
$ hg -R local bookmarks
* test 0:08b9e9f63b32
$ hg clone -e "\"$PYTHON\" \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remote-bookmarks
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
exporting bookmark test
$ hg -R remote-bookmarks bookmarks
test 0:08b9e9f63b32
Check format constraint
-----------------------
$ hg init issue6056 --config format.usegeneraldelta=0 --config format.sparse-revlog=0
$ cd issue6056
$ echo foo > 1
$ echo foo > 2
$ echo foo > 3
$ echo foo > 4
$ echo foo > 5
$ hg add *
Build a bogus repository (sparserevlog without general delta)
$ hg commit -m 'initial changesets'
$ echo 'sparserevlog' >> .hg/requires
$ for x in `$TESTDIR/seq.py 100`; do
> echo $x >> `expr $x % 5 + 1`
> hg commit -m $x
> done
$ cd ..