Benchmark with disabled GIL build and -Xgil=1 isn't enabling GIL

[tonybaloney]

It seems that when you run PYTHON_GIL=1 python benchmark.py the benchmarked functions are being run with the GIL disabled and ignoring the flag.

Benchmark Code

import pyperf
from multiprocessing import Process
from threading import Thread
try:
    import _xxsubinterpreters as interpreters
except ImportError:
    import _interpreters as interpreters

import itertools

DEFAULT_DIGITS = 2000
icount = itertools.count
islice = itertools.islice

def gen_x():
    return map(lambda k: (k, 4 * k + 2, 0, 2 * k + 1), icount(1))


def compose(a, b):
    aq, ar, as_, at = a
    bq, br, bs, bt = b
    return (aq * bq,
            aq * br + ar * bt,
            as_ * bq + at * bs,
            as_ * br + at * bt)


def extract(z, j):
    q, r, s, t = z
    return (q * j + r) // (s * j + t)


def gen_pi_digits():
    z = (1, 0, 0, 1)
    x = gen_x()
    while 1:
        y = extract(z, 3)
        while y != extract(z, 4):
            z = compose(z, next(x))
            y = extract(z, 3)
        z = compose((10, -10 * y, 0, 1), z)
        yield y


def calc_ndigits(n=DEFAULT_DIGITS):
    return list(islice(gen_pi_digits(), n))

test ="""
import itertools

DEFAULT_DIGITS = 2000
icount = itertools.count
islice = itertools.islice

def gen_x():
    return map(lambda k: (k, 4 * k + 2, 0, 2 * k + 1), icount(1))


def compose(a, b):
    aq, ar, as_, at = a
    bq, br, bs, bt = b
    return (aq * bq,
            aq * br + ar * bt,
            as_ * bq + at * bs,
            as_ * br + at * bt)


def extract(z, j):
    q, r, s, t = z
    return (q * j + r) // (s * j + t)


def gen_pi_digits():
    z = (1, 0, 0, 1)
    x = gen_x()
    while 1:
        y = extract(z, 3)
        while y != extract(z, 4):
            z = compose(z, next(x))
            y = extract(z, 3)
        z = compose((10, -10 * y, 0, 1), z)
        yield y


def calc_ndigits(n=DEFAULT_DIGITS):
    return list(islice(gen_pi_digits(), n))
calc_ndigits()
"""

def bench_threading(n):
    # Code to launch specific model
    threads = []
    for _ in range(n):
        t = Thread(target=calc_ndigits)
        t.start()
        threads.append(t)
    for thread in threads:
        thread.join()

def bench_subinterpreters(n, site=True):
    # Code to launch specific model
    def _spawn_sub():
        sid = interpreters.create()
        interpreters.run_string(sid, test)
        interpreters.destroy(sid)

    threads = []
    for _ in range(n):
        t = Thread(target=_spawn_sub)
        t.start()
        threads.append(t)
    for thread in threads:
        thread.join()

def bench_multiprocessing(n):
    # Code to launch specific model
    processes = []
    for _ in range(n):
        t = Process(target=calc_ndigits)
        t.start()
        processes.append(t)
    for process in processes:
        process.join()

if __name__ == "__main__":
    runner = pyperf.Runner()
    runner.metadata['description'] = "Benchmark execution models"
    n = 10
    runner.bench_func('threading', bench_threading, n)
    runner.bench_func('subinterpreters', bench_subinterpreters, n)
    runner.bench_func('multiprocessing', bench_multiprocessing, n)

Results when running a CPython without --disable-gil:

Running the benchmark with PYTHON_GIL=0:

Running the benchmark with a no-gil build, but PYTHON_GIL=1 uses all 4 CPU cores and gives the fastest result (faster than PYTHON_GIL=0) which is wrong--

[tonybaloney]

From python/cpython#118874

[tonybaloney]

@corona10 I saw some mentions from you in the backlog on this topic

[corona10]

Okay this should be fixed, since I am busy before PyCon US, if you want to submit the patch before, you can send it :)
Or I will take a look at it during the PyCon US.

[colesbury]

I'd suggest looking at:

pyperf/pyperf/_utils.py

Line 270 in 555a168

copy_env = ["PATH", "PYTHONPATH", "HOME", "TEMP", "COMSPEC", "SystemRoot", "SystemDrive"]

IIRC, pyperf prevents workers from inheriting environment variables by default, which I've always found more confusing than helpful.

-Xgil is probably also not propagated.

[corona10]

Yeah today, I am working on.

[tonybaloney]

@corona10 there is no rush from me. I just wanted to report the issue