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 > loop.py <<EOF
> from __future__ import absolute_import
> import time
> from mercurial import commands, registrar
>
> cmdtable = {}
> command = registrar.command(cmdtable)
>
> class incrementingtime(object):
> def __init__(self):
> self._time = 0.0
> def __call__(self):
> self._time += 0.25
> return self._time
> time.time = incrementingtime()
>
> @command(b'loop',
> [(b'', b'total', b'', b'override for total'),
> (b'', b'nested', False, b'show nested results'),
> (b'', b'parallel', False, b'show parallel sets of results'),
> (b'', b'warn', False, b'show warning if step divisible by 3')],
> b'hg loop LOOPS',
> norepo=True)
> def loop(ui, loops, **opts):
> loops = int(loops)
> total = None
> if loops >= 0:
> total = loops
> if opts.get('total', None):
> total = int(opts.get('total'))
> nested = False
> if opts.get('nested', None):
> nested = True
> loops = abs(loops)
> showwarn = opts.get('warn', False)
>
> progress = ui.makeprogress(topiclabel, unit=b'loopnum', total=total)
> other = ui.makeprogress(b'other', unit=b'othernum', total=total)
> for i in range(loops):
> progress.update(i, item=getloopitem(i))
> if opts.get('parallel'):
> other.update(i, item=b'other.%d' % i)
> if nested:
> nested_steps = 2
> if i and i % 4 == 0:
> nested_steps = 5
> nested = ui.makeprogress(b'nested', unit=b'nestnum',
> total=nested_steps)
> for j in range(nested_steps):
> nested.update(j, item=b'nested.%d' % j)
> nested.complete()
> if showwarn and i % 3 == 0:
> ui.warn(b'reached step %d\n' %i)
> progress.complete()
>
> topiclabel = b'loop'
> def getloopitem(i):
> return b'loop.%d' % i
>
> EOF
$ cp $HGRCPATH $HGRCPATH.orig
$ echo "[extensions]" >> $HGRCPATH
$ echo "progress=" >> $HGRCPATH
$ echo "loop=`pwd`/loop.py" >> $HGRCPATH
$ echo "[progress]" >> $HGRCPATH
$ echo "format = topic bar number" >> $HGRCPATH
$ echo "assume-tty=1" >> $HGRCPATH
$ echo "width=60" >> $HGRCPATH
test default params, display nothing because of delay
$ hg -y loop 3
$ echo "delay=0" >> $HGRCPATH
$ echo "refresh=0" >> $HGRCPATH
test with delay=0, refresh=0
$ hg -y loop 3
\r (no-eol) (esc)
loop [ ] 0/3\r (no-eol) (esc)
loop [===============> ] 1/3\r (no-eol) (esc)
loop [===============================> ] 2/3\r (no-eol) (esc)
\r (no-eol) (esc)
no progress with --quiet
$ hg -y loop 3 --quiet
test plain mode exception
$ HGPLAINEXCEPT=progress hg -y loop 1
\r (no-eol) (esc)
loop [ ] 0/1\r (no-eol) (esc)
\r (no-eol) (esc)
test nested short-lived topics (which shouldn't display with nestdelay):
$ hg -y loop 3 --nested
\r (no-eol) (esc)
loop [ ] 0/3\r (no-eol) (esc)
loop [===============> ] 1/3\r (no-eol) (esc)
loop [===============================> ] 2/3\r (no-eol) (esc)
\r (no-eol) (esc)
Test nested long-lived topic which has the same name as a short-lived
peer. We shouldn't get stuck showing the short-lived inner steps, and
should go back to skipping the inner steps when the slow nested step
finishes.
$ hg -y loop 7 --nested
\r (no-eol) (esc)
loop [ ] 0/7\r (no-eol) (esc)
loop [=====> ] 1/7\r (no-eol) (esc)
loop [============> ] 2/7\r (no-eol) (esc)
loop [===================> ] 3/7\r (no-eol) (esc)
loop [==========================> ] 4/7\r (no-eol) (esc)
nested [==========================> ] 3/5\r (no-eol) (esc)
nested [===================================> ] 4/5\r (no-eol) (esc)
loop [=================================> ] 5/7\r (no-eol) (esc)
loop [========================================> ] 6/7\r (no-eol) (esc)
\r (no-eol) (esc)
$ hg --config progress.changedelay=0 -y loop 3 --nested
\r (no-eol) (esc)
loop [ ] 0/3\r (no-eol) (esc)
nested [ ] 0/2\r (no-eol) (esc)
nested [======================> ] 1/2\r (no-eol) (esc)
loop [===============> ] 1/3\r (no-eol) (esc)
nested [ ] 0/2\r (no-eol) (esc)
nested [======================> ] 1/2\r (no-eol) (esc)
loop [===============================> ] 2/3\r (no-eol) (esc)
nested [ ] 0/2\r (no-eol) (esc)
nested [======================> ] 1/2\r (no-eol) (esc)
\r (no-eol) (esc)
test two topics being printed in parallel (as when we're doing a local
--pull clone, where you get the unbundle and bundle progress at the
same time):
$ hg loop 3 --parallel
\r (no-eol) (esc)
loop [ ] 0/3\r (no-eol) (esc)
loop [===============> ] 1/3\r (no-eol) (esc)
loop [===============================> ] 2/3\r (no-eol) (esc)
\r (no-eol) (esc)
test refresh is taken in account
$ hg -y --config progress.refresh=100 loop 3
test format options 1
$ hg -y --config 'progress.format=number topic item+2' loop 2
\r (no-eol) (esc)
0/2 loop lo\r (no-eol) (esc)
1/2 loop lo\r (no-eol) (esc)
\r (no-eol) (esc)
test format options 2
$ hg -y --config 'progress.format=number item-3 bar' loop 2
\r (no-eol) (esc)
0/2 p.0 [ ]\r (no-eol) (esc)
1/2 p.1 [=======================> ]\r (no-eol) (esc)
\r (no-eol) (esc)
test format options and indeterminate progress
$ hg -y --config 'progress.format=number item bar' loop -- -2
\r (no-eol) (esc)
0 loop.0 [ <=> ]\r (no-eol) (esc)
1 loop.1 [ <=> ]\r (no-eol) (esc)
\r (no-eol) (esc)
make sure things don't fall over if count > total
$ hg -y loop --total 4 6
\r (no-eol) (esc)
loop [ ] 0/4\r (no-eol) (esc)
loop [===========> ] 1/4\r (no-eol) (esc)
loop [=======================> ] 2/4\r (no-eol) (esc)
loop [===================================> ] 3/4\r (no-eol) (esc)
loop [===============================================>] 4/4\r (no-eol) (esc)
loop [ <=> ] 5/4\r (no-eol) (esc)
\r (no-eol) (esc)
test interaction with ui.warn
$ hg loop --warn 6
\r (no-eol) (esc)
loop [ ] 0/6\r (no-eol) (esc)
\r (no-eol) (esc)
reached step 0
\r (no-eol) (esc)
loop [=======> ] 1/6\r (no-eol) (esc)
loop [===============> ] 2/6\r (no-eol) (esc)
loop [=======================> ] 3/6\r (no-eol) (esc)
\r (no-eol) (esc)
reached step 3
\r (no-eol) (esc)
loop [===============================> ] 4/6\r (no-eol) (esc)
loop [=======================================> ] 5/6\r (no-eol) (esc)
\r (no-eol) (esc)
test interaction with ui.timestamp-output
XXX: The timestamp on Windows with py2 hg is in 1970, and py3 hg is now. But
the py2/py3 checks here test the test runner, not the binary. The Windows lines
can be dropped when switching to py3-only.
$ hg loop --warn --config ui.timestamp-output=true 6
\r (no-eol) (esc)
loop [ ] 0/6\r (no-eol) (esc)
\r (no-eol) (esc)
[*T*] reached step 0 (glob) (windows !)
\[20[2-9][0-9]-[01][0-9]-[0-3][0-9]T[0-5][0-9]:[0-5][0-9]:[0-5][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9]\] reached step 0 (re) (no-windows !)
\r (no-eol) (esc)
loop [=======> ] 1/6\r (no-eol) (esc)
loop [===============> ] 2/6\r (no-eol) (esc)
loop [=======================> ] 3/6\r (no-eol) (esc)
\r (no-eol) (esc)
[*T*] reached step 3 (glob) (windows !)
\[20[2-9][0-9]-[01][0-9]-[0-3][0-9]T[0-5][0-9]:[0-5][0-9]:[0-5][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9]\] reached step 3 (re) (no-windows !)
\r (no-eol) (esc)
loop [===============================> ] 4/6\r (no-eol) (esc)
loop [=======================================> ] 5/6\r (no-eol) (esc)
\r (no-eol) (esc)
test immediate progress completion
$ hg -y loop 0
test delay time estimates
#if no-chg
$ cp $HGRCPATH.orig $HGRCPATH
$ echo "[extensions]" >> $HGRCPATH
$ echo "mocktime=$TESTDIR/mocktime.py" >> $HGRCPATH
$ echo "progress=" >> $HGRCPATH
$ echo "loop=`pwd`/loop.py" >> $HGRCPATH
$ echo "[progress]" >> $HGRCPATH
$ echo "assume-tty=1" >> $HGRCPATH
$ echo "delay=25" >> $HGRCPATH
$ echo "width=60" >> $HGRCPATH
$ MOCKTIME=11 hg -y loop 8
\r (no-eol) (esc)
loop [=========> ] 2/8 1m07s\r (no-eol) (esc)
loop [===============> ] 3/8 56s\r (no-eol) (esc)
loop [=====================> ] 4/8 45s\r (no-eol) (esc)
loop [==========================> ] 5/8 34s\r (no-eol) (esc)
loop [================================> ] 6/8 23s\r (no-eol) (esc)
loop [=====================================> ] 7/8 12s\r (no-eol) (esc)
\r (no-eol) (esc)
$ MOCKTIME=10000 hg -y loop 4
\r (no-eol) (esc)
loop [ ] 0/4\r (no-eol) (esc)
loop [=========> ] 1/4 8h21m\r (no-eol) (esc)
loop [====================> ] 2/4 5h34m\r (no-eol) (esc)
loop [==============================> ] 3/4 2h47m\r (no-eol) (esc)
\r (no-eol) (esc)
$ MOCKTIME=1000000 hg -y loop 4
\r (no-eol) (esc)
loop [ ] 0/4\r (no-eol) (esc)
loop [=========> ] 1/4 5w00d\r (no-eol) (esc)
loop [====================> ] 2/4 3w03d\r (no-eol) (esc)
loop [=============================> ] 3/4 11d14h\r (no-eol) (esc)
\r (no-eol) (esc)
$ MOCKTIME=14000000 hg -y loop 4
\r (no-eol) (esc)
loop [ ] 0/4\r (no-eol) (esc)
loop [=========> ] 1/4 1y18w\r (no-eol) (esc)
loop [===================> ] 2/4 46w03d\r (no-eol) (esc)
loop [=============================> ] 3/4 23w02d\r (no-eol) (esc)
\r (no-eol) (esc)
Non-linear progress:
$ MOCKTIME='20 20 20 20 20 20 20 20 20 20 500 500 500 500 500 20 20 20 20 20' hg -y loop 20
\r (no-eol) (esc)
loop [=> ] 1/20 6m21s\r (no-eol) (esc)
loop [===> ] 2/20 6m01s\r (no-eol) (esc)
loop [=====> ] 3/20 5m41s\r (no-eol) (esc)
loop [=======> ] 4/20 5m21s\r (no-eol) (esc)
loop [=========> ] 5/20 5m01s\r (no-eol) (esc)
loop [===========> ] 6/20 4m41s\r (no-eol) (esc)
loop [=============> ] 7/20 4m21s\r (no-eol) (esc)
loop [===============> ] 8/20 4m01s\r (no-eol) (esc)
loop [================> ] 9/20 25m40s\r (no-eol) (esc)
loop [===================> ] 10/20 1h06m\r (no-eol) (esc)
loop [=====================> ] 11/20 1h13m\r (no-eol) (esc)
loop [=======================> ] 12/20 1h07m\r (no-eol) (esc)
loop [========================> ] 13/20 58m19s\r (no-eol) (esc)
loop [===========================> ] 14/20 7m09s\r (no-eol) (esc)
loop [=============================> ] 15/20 3m38s\r (no-eol) (esc)
loop [===============================> ] 16/20 2m15s\r (no-eol) (esc)
loop [=================================> ] 17/20 1m27s\r (no-eol) (esc)
loop [====================================> ] 18/20 52s\r (no-eol) (esc)
loop [======================================> ] 19/20 25s\r (no-eol) (esc)
\r (no-eol) (esc)
Time estimates should not fail when there's no end point:
$ MOCKTIME=11 hg -y loop -- -4
\r (no-eol) (esc)
loop [ <=> ] 2\r (no-eol) (esc)
loop [ <=> ] 3\r (no-eol) (esc)
\r (no-eol) (esc)
#endif
test line trimming by '[progress] width', when progress topic contains
multi-byte characters, of which length of byte sequence and columns in
display are different from each other.
$ cp $HGRCPATH.orig $HGRCPATH
$ cat >> $HGRCPATH <<EOF
> [extensions]
> progress=
> loop=`pwd`/loop.py
> [progress]
> assume-tty = 1
> delay = 0
> refresh = 0
> EOF
$ rm -f loop.pyc
$ cat >> loop.py <<EOF
> # use non-ascii characters as topic label of progress
> # 2 x 4 = 8 columns, but 3 x 4 = 12 bytes
> topiclabel = u'\u3042\u3044\u3046\u3048'.encode('utf-8')
> EOF
$ cat >> $HGRCPATH <<EOF
> [progress]
> format = topic number
> width= 12
> EOF
$ hg --encoding utf-8 -y loop --total 3 3
\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 0/3\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 1/3\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 2/3\r (no-eol) (esc)
\r (no-eol) (esc)
test calculation of bar width, when progress topic contains multi-byte
characters, of which length of byte sequence and columns in display
are different from each other.
$ cat >> $HGRCPATH <<EOF
> [progress]
> format = topic bar
> width= 21
> # progwidth should be 9 (= 21 - (8+1) - 3)
> EOF
$ hg --encoding utf-8 -y loop --total 3 3
\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 [ ]\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 [==> ]\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88 [=====> ]\r (no-eol) (esc)
\r (no-eol) (esc)
test trimming progress items, when they contain multi-byte characters,
of which length of byte sequence and columns in display are different
from each other.
$ rm -f loop.pyc
$ rm -Rf __pycache__
$ cat >> loop.py <<EOF
> # use non-ascii characters as loop items of progress
> loopitems = [
> u'\u3042\u3044'.encode('utf-8'), # 2 x 2 = 4 columns
> u'\u3042\u3044\u3046'.encode('utf-8'), # 2 x 3 = 6 columns
> u'\u3042\u3044\u3046\u3048'.encode('utf-8'), # 2 x 4 = 8 columns
> ]
> def getloopitem(i):
> return loopitems[i % len(loopitems)]
> EOF
$ cat >> $HGRCPATH <<EOF
> [progress]
> # trim at tail side
> format = item+6
> EOF
$ hg --encoding utf-8 -y loop --total 3 3
\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84 \r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\r (no-eol) (esc)
\r (no-eol) (esc)
$ cat >> $HGRCPATH <<EOF
> [progress]
> # trim at left side
> format = item-6
> EOF
$ hg --encoding utf-8 -y loop --total 3 3
\r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84 \r (no-eol) (esc)
\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\r (no-eol) (esc)
\xe3\x81\x84\xe3\x81\x86\xe3\x81\x88\r (no-eol) (esc)
\r (no-eol) (esc)