contrib/perf-utils/search-discovery-case

stream-clone: disable gc for the initial section for the v3 format

The number of small container created turn Python in a gc-frenzy that seriously
impact performance.

This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:

base-line:   35.04 seconds
prev-change: 24.51 seconds (-30%)
prev-change: 20.88 seconds (-40%)
this-change: 14.22 seconds (-60% from baseline; -31% from prev)

#!/usr/bin/env python3
# Search for interesting discovery instance
#
#  search-discovery-case REPO [REPO]…
#
# This use a subsetmaker extension (next to this script) to generate a steam of
# random discovery instance. When interesting case are discovered, information
# about them are print on the stdout.

import json
import os
import queue
import random
import signal
import subprocess
import sys
import threading

this_script = os.path.abspath(sys.argv[0])
this_dir = os.path.dirname(this_script)
hg_dir = os.path.join(this_dir, '..', '..')
HG_REPO = os.path.normpath(hg_dir)
HG_BIN = os.path.join(HG_REPO, 'hg')

JOB = int(os.environ.get('NUMBER_OF_PROCESSORS', 8))


SLICING = ('scratch', 'randomantichain', 'rev')


def nb_revs(repo_path):
    cmd = [
        HG_BIN,
        '--repository',
        repo_path,
        'log',
        '--template',
        '{rev}',
        '--rev',
        'tip',
    ]
    s = subprocess.Popen(cmd, stdout=subprocess.PIPE)
    out, err = s.communicate()
    return int(out)


repos = []
for repo in sys.argv[1:]:
    size = nb_revs(repo)
    repos.append((repo, size))


def pick_one(repo):
    pick = random.choice(SLICING)
    seed = random.randint(0, 100000)
    if pick == 'scratch':
        start = int(repo[1] * 0.3)
        end = int(repo[1] * 0.7)
        nb = random.randint(start, end)
        return ('scratch', nb, seed)
    elif pick == 'randomantichain':
        return ('randomantichain', seed)
    elif pick == 'rev':
        start = int(repo[1] * 0.3)
        end = int(repo[1])
        rev = random.randint(start, end)
        return ('rev', rev)
    else:
        assert False


done = threading.Event()
cases = queue.Queue(maxsize=10 * JOB)
results = queue.Queue()


def worker():
    while not done.is_set():
        c = cases.get()
        if c is None:
            return
        try:
            res = process(c)
            results.put((c, res))
        except Exception as exc:
            print('processing-failed: %s %s' % (c, exc), file=sys.stderr)
        c = (c[0], c[2], c[1])
        try:
            res = process(c)
            results.put((c, res))
        except Exception as exc:
            print('processing-failed: %s %s' % (c, exc), file=sys.stderr)


SUBSET_PATH = os.path.join(HG_REPO, 'contrib', 'perf-utils', 'subsetmaker.py')


CMD_BASE = (
    HG_BIN,
    'debugdiscovery',
    '--template',
    'json',
    '--config',
    'extensions.subset=%s' % SUBSET_PATH,
)
#    '--local-as-revs "$left" --local-as-revs "$right"'
#    > /data/discovery-references/results/disco-mozilla-unified-$1-$2.txt
#        )


def to_revsets(case):
    t = case[0]
    if t == 'scratch':
        return 'not scratch(all(), %d, "%d")' % (case[1], case[2])
    elif t == 'randomantichain':
        return '::randomantichain(all(), "%d")' % case[1]
    elif t == 'rev':
        return '::%d' % case[1]
    else:
        assert False


def process(case):
    (repo, left, right) = case
    cmd = list(CMD_BASE)
    cmd.append('-R')
    cmd.append(repo[0])
    cmd.append('--local-as-revs')
    cmd.append(to_revsets(left))
    cmd.append('--remote-as-revs')
    cmd.append(to_revsets(right))
    s = subprocess.Popen(cmd, stdout=subprocess.PIPE)
    out, err = s.communicate()
    return json.loads(out)[0]


def interesting_boundary(res):
    """check if a case is interesting or not

    For now we are mostly interrested in case were we do multiple roundstrip
    and where the boundary is somewhere in the middle of the undecided set.

    Ideally, we would make this configurable, but this is not a focus for now

    return None or (
        round-trip,
        undecided-common,
        undecided-missing,
        total-revs,
        common-revs,
        missing-revs,
    )
    """
    roundtrips = res["total-roundtrips"]
    if roundtrips <= 1:
        return None
    total_revs = res["nb-revs"]
    common_revs = res["nb-revs-common"]
    missing_revs = res["nb-revs-missing"]
    undecided_common = res["nb-ini_und-common"]
    undecided_missing = res["nb-ini_und-missing"]
    if undecided_common == 0:
        return None
    if undecided_missing == 0:
        return None
    return (
        roundtrips,
        undecided_common,
        undecided_missing,
        total_revs,
        common_revs,
        missing_revs,
    )


def end(*args, **kwargs):
    done.set()


def format_case(case):
    return '-'.join(str(s) for s in case)


signal.signal(signal.SIGINT, end)

for i in range(JOB):
    threading.Thread(target=worker).start()

nb_cases = 0
while not done.is_set():
    repo = random.choice(repos)
    left = pick_one(repo)
    right = pick_one(repo)
    cases.put((repo, left, right))
    while not results.empty():
        # results has a single reader so this is fine
        c, res = results.get_nowait()
        boundary = interesting_boundary(res)
        if boundary is not None:
            print(c[0][0], format_case(c[1]), format_case(c[2]), *boundary)
            sys.stdout.flush()

    nb_cases += 1
    if not nb_cases % 100:
        print('[%d cases generated]' % nb_cases, file=sys.stderr)

for i in range(JOB):
    try:
        cases.put_nowait(None)
    except queue.Full:
        pass

print('[%d cases generated]' % nb_cases, file=sys.stderr)
print('[ouput generation is over]' % nb_cases, file=sys.stderr)