[BUG] setuptools.Distribution may be leaking references

[lysnikolaou]

setuptools version

67.8.0

Python version

3.11.3

OS

macOS

Description

Some background info: When adding the new PEG parser to CPython back in 3.9, we also added some tests that test the new parser generator. In order to do so, the tests build an extension module with a lot of different grammar, use that to parse a piece of code, and then compare the resulting syntax trees with the expected one.

Up until 3.11, we were using distutils to build the extension module. After the removal of distutils in 3.12, we recently migrated into using setuptools in python/cpython#104798. Since that PR was merged, some buildbots fail due to this test cause of some refleaks (example). Me and @pablogsal were able to bisect that down to the call to setuptools.Distribution in setup.py.

We're still not sure whether that's a true refleak in setuptools or some caching that setuptools does, which leads to the CPython test suite to fail, so I'm opening this issue to hopefully start a discussion on whether CPython needs to change something or setuptools.

I'm also including below a little script that reproduces this without the need of the CPython test suite or anything else.

Expected behavior

No refleaks.

How to Reproduce

Run the following script:

import sys

from setuptools import Extension, Distribution

int_pool = {value: value for value in range(-1000, 1000)}
def get_pooled_int(value):
    return int_pool.setdefault(value, value)


def build():
    with open("hello.c", "w") as f:
        f.write("int spam() {\n")
        f.write("    return 1;\n")
        f.write("}\n")
    extension = Extension(
        "something",
        sources=["hello.c"],
    )
    Distribution({"name": "something", "ext_modules": [extension]})

def main(run_build_between=False):
    build()
    build()
    build()

    getallocatedblocks = sys.getallocatedblocks
    gettotalrefcount = sys.gettotalrefcount
    getunicodeinternedsize = sys.getunicodeinternedsize

    interned_before = getunicodeinternedsize()
    alloc_before = getallocatedblocks() - interned_before
    rc_before = gettotalrefcount() - interned_before * 2

    if run_build_between:
        build()

    interned_after = getunicodeinternedsize()
    alloc_after = getallocatedblocks() - interned_after
    rc_after = gettotalrefcount() - interned_after * 2
    rc_delta = get_pooled_int(rc_after - rc_before)
    alloc_delta = get_pooled_int(alloc_after - alloc_before)
    print(f"{run_build_between=}: {rc_delta=} {alloc_delta=}")


if __name__ == "__main__":
    main(run_build_between=False)
    main(run_build_between=True)

Output

run_build_between=False: rc_delta=3 alloc_delta=3
run_build_between=True: rc_delta=238 alloc_delta=180

[abravalheri]

Hi @lysnikolaou, thank you very much for opening this issue.

I don't have access to a macOS machine, so I will not be able to help with this problem.

However I noticed that you reproducer script uses sys.gettotalrefcount and
sys.getunicodeinternedsize don't seem to be defined as public functions on the Python docs for 3.11. They also don't seem to be available on Linux.

Are those undocumented properties that only exist on macOS?

[erlend-aasland]

However I noticed that you reproducer script uses sys.gettotalrefcount and sys.getunicodeinternedsize don't seem to be defined as public functions on the Python docs for 3.11. They also don't seem to be available on Linux.

It's an attribute available (on all platforms) in debug builds only: https://docs.python.org/3/using/configure.html#python-debug-build

[abravalheri]

Hi @erlend-aasland, thank you very much for the clarification. sys.getunicodeinternedsize still does not seem to be available on Linux, Python 3.11.3, even when --with-pydebug is added to the config args:

I tried modifying the standard Dockerfile to add this option.

FROM buildpack-deps:bullseye

# ensure local python is preferred over distribution python
ENV PATH /usr/local/bin:$PATH

# http://bugs.python.org/issue19846
# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
ENV LANG C.UTF-8

# runtime dependencies
RUN set -eux; \
        apt-get update; \
        apt-get install -y --no-install-recommends \
                libbluetooth-dev \
                tk-dev \
                uuid-dev \
                vim \
                wget \
                curl \
        ; \
        rm -rf /var/lib/apt/lists/*

ENV GPG_KEY A035C8C19219BA821ECEA86B64E628F8D684696D
ENV PYTHON_VERSION 3.11.3

RUN set -eux; \
        \
        wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz"; \
        wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc"; \
        GNUPGHOME="$(mktemp -d)"; export GNUPGHOME; \
        gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY"; \
        gpg --batch --verify python.tar.xz.asc python.tar.xz; \
        gpgconf --kill all; \
        rm -rf "$GNUPGHOME" python.tar.xz.asc; \
        mkdir -p /usr/src/python; \
        tar --extract --directory /usr/src/python --strip-components=1 --file python.tar.xz; \
        rm python.tar.xz; \
        \
        cd /usr/src/python; \
        gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)"; \
        ./configure \
                --build="$gnuArch" \
                --enable-loadable-sqlite-extensions \
                --enable-optimizations \
                --enable-option-checking=fatal \
                --enable-shared \
                --with-lto \
                --with-system-expat \
                --without-ensurepip \
                --with-pydebug \
        ; \
        nproc="$(nproc)"; \
        EXTRA_CFLAGS="$(dpkg-buildflags --get CFLAGS)"; \
        LDFLAGS="$(dpkg-buildflags --get LDFLAGS)"; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:-}" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
        ; \
# https://github.com/docker-library/python/issues/784
# prevent accidental usage of a system installed libpython of the same version
        rm python; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:--Wl},-rpath='\$\$ORIGIN/../lib'" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
                python \
        ; \
        make install; \
        \
# enable GDB to load debugging data: https://github.com/docker-library/python/pull/701
        bin="$(readlink -ve /usr/local/bin/python3)"; \
        dir="$(dirname "$bin")"; \
        mkdir -p "/usr/share/gdb/auto-load/$dir"; \
        cp -vL Tools/gdb/libpython.py "/usr/share/gdb/auto-load/$bin-gdb.py"; \
        \
        cd /; \
        rm -rf /usr/src/python; \
        \
        find /usr/local -depth \
                \( \
                        \( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
                        -o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name 'libpython*.a' \) \) \
                \) -exec rm -rf '{}' + \
        ; \
        \
        ldconfig; \
        \
        python3 --version

# make some useful symlinks that are expected to exist ("/usr/local/bin/python" and friends)
RUN set -eux; \
        for src in idle3 pydoc3 python3 python3-config; do \
                dst="$(echo "$src" | tr -d 3)"; \
                [ -s "/usr/local/bin/$src" ]; \
                [ ! -e "/usr/local/bin/$dst" ]; \
                ln -svT "$src" "/usr/local/bin/$dst"; \
        done

# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
ENV PYTHON_PIP_VERSION 22.3.1
# https://github.com/docker-library/python/issues/365
ENV PYTHON_SETUPTOOLS_VERSION 67.8.0
# https://github.com/pypa/get-pip
ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/0d8570dc44796f4369b652222cf176b3db6ac70e/public/get-pip.py
ENV PYTHON_GET_PIP_SHA256 96461deced5c2a487ddc65207ec5a9cffeca0d34e7af7ea1afc470ff0d746207

RUN set -eux; \
        \
        wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
        echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum -c -; \
        \
        export PYTHONDONTWRITEBYTECODE=1; \
        \
        python get-pip.py \
                --disable-pip-version-check \
                --no-cache-dir \
                --no-compile \
                "pip==$PYTHON_PIP_VERSION" \
                "setuptools==$PYTHON_SETUPTOOLS_VERSION" \
        ; \
        rm -f get-pip.py; \
        \
        pip --version

WORKDIR /tmp/test_setuptools
COPY script.py .

CMD ["python3"]

But I still get an AttributeError: module 'sys' has no attribute 'getunicodeinternedsize' exception.

Sorry for insisting in this topic (even when I will not be able to test on a macOS machine). I just want to make sure that anyone that can investigate this issue has all the parameters for running the reproducer correctly.

@lysnikolaou would it be possible to edit the initial post to improve the instructions on how to reproduce the problem?

[abravalheri]

I did some tests on Linux (buildpack-deps:bullseye base docker image) using Python 3.12.0b2 and I could observe similar numbers for the rc_delta and alloc_delta reported.

I am not sure if this is also supposed to happen for this combination of system / Python version as they are different from the initial report.

I noticed one thing:

• There are some idioms used in setuptools/distutils:

  • Some parts of the code use "circular references", for example:

    • A Distribution object will hold references to command objects. Command objects hold a reference to the Distribution object. The same is also true for a setuptools.discovery.ConfigDiscovery object.
    • If I replace these "circular references" with a weakref.proxy the number of rc_delta goes down:

    run_build_between=False: rc_delta=3 alloc_delta=3
    run_build_between=True: rc_delta=66 alloc_delta=121
    

Is this something relevant? Is this idiom of using "circular references" something that the garbage collector has problems to deal with and should be manually replaced by weakrefs?

On top of this test with weakref, I tried to edit the script with the following:

- from setuptools import Extension, Distribution
+ import _distutils_hack.override
+ from distutils.core import Extension, Distribution

After running the script, the obtained rc_delta and alloc_delta were very similar to the result with the weakref replacement:

run_build_between=False: rc_delta=3 alloc_delta=3
run_build_between=True: rc_delta=66 alloc_delta=118

My conclusion is that the rest of the references were related to the MetaPathFinder used for redirecting distutils.
In particular, the MetaPathFinder imports setuptools._distutils, which imply that setuptools/__init__.py runs.

On top of that, I did another experiment: commenting the monkey.patch_all() line on the bottom of the setuptools/__init__.py file. When I run the modified benchmark script again, rc_delta and alloc_delta goes down again:

run_build_between=False: rc_delta=3 alloc_delta=3
run_build_between=True: rc_delta=9 alloc_delta=9

So it seems that the remaining objects are related to the monkey patching that setuptools does of distutils. Is there any chance the use of importlib_metadata.entry_points is involved with that? (It does use some caching, right?)

(I am using a git checkout of setuptools in an environment without setuptools installed, adding the benchmark script to the root of the project)

[erlend-aasland]

Hi @erlend-aasland, thank you very much for the clarification. sys.getunicodeinternedsize still does not seem to be available on Linux, Python 3.11.3, even when --with-pydebug is added to the config args:

Yes, that API was added in 3.12.

[abravalheri]

Yes, that API was added in 3.12.

Ok, that was a bit confusing because the original issue post specifies Python 3.11.3 on macOS.

---

Is there any chance the use of importlib_metadata.entry_points is involved with that? (It does use some caching, right?)

I was investigating this possibility, so I did run a modified version of the benchmark script:

# script.py -- modified to test `entry_points`
import sys
from importlib.metadata import entry_points

int_pool = {value: value for value in range(-1000, 1000)}
def get_pooled_int(value):
    return int_pool.setdefault(value, value)


def build():
    group = 'setuptools.finalize_distribution_options'
    entry_points(group=group)


def main(run_build_between=False):
    build()
    build()
    build()

    getallocatedblocks = sys.getallocatedblocks
    gettotalrefcount = sys.gettotalrefcount
    getunicodeinternedsize = sys.getunicodeinternedsize

    interned_before = getunicodeinternedsize()
    alloc_before = getallocatedblocks() - interned_before
    rc_before = gettotalrefcount() - interned_before * 2

    if run_build_between:
        build()

    interned_after = getunicodeinternedsize()
    alloc_after = getallocatedblocks() - interned_after
    rc_after = gettotalrefcount() - interned_after * 2
    rc_delta = get_pooled_int(rc_after - rc_before)
    alloc_delta = get_pooled_int(alloc_after - alloc_before)
    print(f"{run_build_between=}: {rc_delta=} {alloc_delta=}")


if __name__ == "__main__":
    main(run_build_between=False)
    main(run_build_between=True)

..and run it using this Dockerfile

FROM buildpack-deps:bullseye AS base

# ensure local python is preferred over distribution python
ENV PATH /usr/local/bin:$PATH

# http://bugs.python.org/issue19846
# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
ENV LANG C.UTF-8

# runtime dependencies
RUN set -eux; \
        apt-get update; \
        apt-get install -y --no-install-recommends \
                libbluetooth-dev \
                tk-dev \
                uuid-dev \
        ; \
        rm -rf /var/lib/apt/lists/*

ENV GPG_KEY 7169605F62C751356D054A26A821E680E5FA6305
ENV PYTHON_VERSION 3.12.0b2

RUN set -eux; \
        \
        wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz"; \
        wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc"; \
        GNUPGHOME="$(mktemp -d)"; export GNUPGHOME; \
        gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY"; \
        gpg --batch --verify python.tar.xz.asc python.tar.xz; \
        gpgconf --kill all; \
        rm -rf "$GNUPGHOME" python.tar.xz.asc; \
        mkdir -p /usr/src/python; \
        tar --extract --directory /usr/src/python --strip-components=1 --file python.tar.xz; \
        rm python.tar.xz; \
        \
        cd /usr/src/python; \
        gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)"; \
        ./configure \
                --build="$gnuArch" \
                --enable-loadable-sqlite-extensions \
                --enable-optimizations \
                --enable-option-checking=fatal \
                --enable-shared \
                --with-lto \
                --with-system-expat \
                --without-ensurepip \
                --with-pydebug \
        ; \
        nproc="$(nproc)"; \
        EXTRA_CFLAGS="$(dpkg-buildflags --get CFLAGS)"; \
        LDFLAGS="$(dpkg-buildflags --get LDFLAGS)"; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:-}" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
        ; \
# https://github.com/docker-library/python/issues/784
# prevent accidental usage of a system installed libpython of the same version
        rm python; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:--Wl},-rpath='\$\$ORIGIN/../lib'" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
                python \
        ; \
        make install; \
        \
# enable GDB to load debugging data: https://github.com/docker-library/python/pull/701
        bin="$(readlink -ve /usr/local/bin/python3)"; \
        dir="$(dirname "$bin")"; \
        mkdir -p "/usr/share/gdb/auto-load/$dir"; \
        cp -vL Tools/gdb/libpython.py "/usr/share/gdb/auto-load/$bin-gdb.py"; \
        \
        cd /; \
        rm -rf /usr/src/python; \
        \
        find /usr/local -depth \
                \( \
                        \( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
                        -o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name 'libpython*.a' \) \) \
                \) -exec rm -rf '{}' + \
        ; \
        \
        ldconfig; \
        \
        python3 --version

# make some useful symlinks that are expected to exist ("/usr/local/bin/python" and friends)
RUN set -eux; \
        for src in idle3 pydoc3 python3 python3-config; do \
                dst="$(echo "$src" | tr -d 3)"; \
                [ -s "/usr/local/bin/$src" ]; \
                [ ! -e "/usr/local/bin/$dst" ]; \
                ln -svT "$src" "/usr/local/bin/$dst"; \
        done

# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
ENV PYTHON_PIP_VERSION 23.1.2
# https://github.com/pypa/get-pip
ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/0d8570dc44796f4369b652222cf176b3db6ac70e/public/get-pip.py
ENV PYTHON_GET_PIP_SHA256 96461deced5c2a487ddc65207ec5a9cffeca0d34e7af7ea1afc470ff0d746207

RUN set -eux; \
        \
        wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
        echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum -c -; \
        \
        export PYTHONDONTWRITEBYTECODE=1; \
        \
        python get-pip.py \
                --disable-pip-version-check \
                --no-cache-dir \
                --no-compile \
                "pip==$PYTHON_PIP_VERSION" \
        ; \
        rm -f get-pip.py; \
        \
        pip --version


FROM base as test_env

RUN set -eux; \
        python -m pip uninstall setuptools

WORKDIR /tmp/test_refs
COPY script.py .

CMD ["/bin/bash"]

As a result, I can see

run_build_between=False: rc_delta=3 alloc_delta=3
run_build_between=True: rc_delta=31 alloc_delta=30

So some part of the increase in rc_delta and alloc_delta seem to be related to setuptools use of importlib.metadata.

[abravalheri]

Based on the previous results I ran the following test:

# script.py
import sys
from importlib.metadata import entry_points
from setuptools import Extension, Distribution

int_pool = {value: value for value in range(-1000, 1000)}
def get_pooled_int(value):
    return int_pool.setdefault(value, value)


def importlib_test():
    group = 'setuptools.finalize_distribution_options'
    entry_points(group=group)
    group = 'setuptools.setup_keywords'
    entry_points(group=group)


def build():
    with open("hello.c", "w") as f:
        f.write("int spam() {\n")
        f.write("    return 1;\n")
        f.write("}\n")
    extension = Extension(
        "something",
        sources=["hello.c"],
    )
    Distribution({"name": "something", "ext_modules": [extension]})


getallocatedblocks = sys.getallocatedblocks
gettotalrefcount = sys.gettotalrefcount
getunicodeinternedsize = sys.getunicodeinternedsize


def _test_rc(test_fn, run_in_between):
    rc_delta, alloc_delta = 0, 0
    while rc_delta <= 0 or alloc_delta <= 0:
        test_fn()
        test_fn()
        test_fn()

        interned_before = getunicodeinternedsize()
        alloc_before = getallocatedblocks() - interned_before
        rc_before = gettotalrefcount() - interned_before * 2

        if run_in_between:
            test_fn()

        interned_after = getunicodeinternedsize()
        alloc_after = getallocatedblocks() - interned_after
        rc_after = gettotalrefcount() - interned_after * 2
        rc_delta = get_pooled_int(rc_after - rc_before)
        alloc_delta = get_pooled_int(alloc_after - alloc_before)

    return rc_delta, alloc_delta


def test_rc(test_fn, run_in_between, n=100):
    results = [_test_rc(test_fn, run_in_between) for _ in range(n)]
    return [int(round(sum(x) / len(x))) for x in zip(*results)]


def main():
    without_setuptools_rc_delta, without_setuptools_alloc_delta = test_rc(build, False)
    with_setuptools_rc_delta, with_setuptools_alloc_delta = test_rc(build, True)
    importlib_rc_delta, importlib_alloc_delta = test_rc(importlib_test, True)

    print(f"{without_setuptools_rc_delta=} {without_setuptools_alloc_delta=}")
    print(f"{with_setuptools_rc_delta=} {with_setuptools_alloc_delta=}")
    print(f"{importlib_rc_delta=} {importlib_alloc_delta=}")


if __name__ == "__main__":
    main()

# patch.diff
diff --git a/setuptools/dist.py b/setuptools/dist.py
index e5a7b8ed..4494fa77 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -5,6 +5,7 @@ import sys
 import re
 import os
 import numbers
+import weakref
 import distutils.log
 import distutils.core
 import distutils.cmd
@@ -512,7 +513,7 @@ class Distribution(_Distribution):
         self._orig_install_requires = []
         self._tmp_extras_require = defaultdict(ordered_set.OrderedSet)

-        self.set_defaults = ConfigDiscovery(self)
+        self.set_defaults = ConfigDiscovery(weakref.proxy(self))

         self._set_metadata_defaults(attrs)

@@ -991,6 +992,9 @@ class Distribution(_Distribution):
         else:
             return _Distribution.get_command_class(self, command)

+    def get_command_obj(self, command, create=1):
+        return _Distribution.get_command_obj(weakref.proxy(self), command, create)
+
     def print_commands(self):
         for ep in metadata.entry_points(group='distutils.commands'):
             if ep.name not in self.cmdclass:

Dockerfile

FROM buildpack-deps:bullseye AS base

# ensure local python is preferred over distribution python
ENV PATH /usr/local/bin:$PATH

# http://bugs.python.org/issue19846
# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
ENV LANG C.UTF-8

# runtime dependencies
RUN set -eux; \
        apt-get update; \
        apt-get install -y --no-install-recommends \
                libbluetooth-dev \
                tk-dev \
                uuid-dev \
        ; \
        rm -rf /var/lib/apt/lists/*

ENV GPG_KEY 7169605F62C751356D054A26A821E680E5FA6305
ENV PYTHON_VERSION 3.12.0b2

RUN set -eux; \
        \
        wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz"; \
        wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc"; \
        GNUPGHOME="$(mktemp -d)"; export GNUPGHOME; \
        gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY"; \
        gpg --batch --verify python.tar.xz.asc python.tar.xz; \
        gpgconf --kill all; \
        rm -rf "$GNUPGHOME" python.tar.xz.asc; \
        mkdir -p /usr/src/python; \
        tar --extract --directory /usr/src/python --strip-components=1 --file python.tar.xz; \
        rm python.tar.xz; \
        \
        cd /usr/src/python; \
        gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)"; \
        ./configure \
                --build="$gnuArch" \
                --enable-loadable-sqlite-extensions \
                --enable-optimizations \
                --enable-option-checking=fatal \
                --enable-shared \
                --with-lto \
                --with-system-expat \
                --without-ensurepip \
                --with-pydebug \
        ; \
        nproc="$(nproc)"; \
        EXTRA_CFLAGS="$(dpkg-buildflags --get CFLAGS)"; \
        LDFLAGS="$(dpkg-buildflags --get LDFLAGS)"; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:-}" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
        ; \
# https://github.com/docker-library/python/issues/784
# prevent accidental usage of a system installed libpython of the same version
        rm python; \
        make -j "$nproc" \
                "EXTRA_CFLAGS=${EXTRA_CFLAGS:-}" \
                "LDFLAGS=${LDFLAGS:--Wl},-rpath='\$\$ORIGIN/../lib'" \
                "PROFILE_TASK=${PROFILE_TASK:-}" \
                python \
        ; \
        make install; \
        \
# enable GDB to load debugging data: https://github.com/docker-library/python/pull/701
        bin="$(readlink -ve /usr/local/bin/python3)"; \
        dir="$(dirname "$bin")"; \
        mkdir -p "/usr/share/gdb/auto-load/$dir"; \
        cp -vL Tools/gdb/libpython.py "/usr/share/gdb/auto-load/$bin-gdb.py"; \
        \
        cd /; \
        rm -rf /usr/src/python; \
        \
        find /usr/local -depth \
                \( \
                        \( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
                        -o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name 'libpython*.a' \) \) \
                \) -exec rm -rf '{}' + \
        ; \
        \
        ldconfig; \
        \
        python3 --version

# make some useful symlinks that are expected to exist ("/usr/local/bin/python" and friends)
RUN set -eux; \
        for src in idle3 pydoc3 python3 python3-config; do \
                dst="$(echo "$src" | tr -d 3)"; \
                [ -s "/usr/local/bin/$src" ]; \
                [ ! -e "/usr/local/bin/$dst" ]; \
                ln -svT "$src" "/usr/local/bin/$dst"; \
        done

# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
ENV PYTHON_PIP_VERSION 23.1.2
# https://github.com/pypa/get-pip
ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/0d8570dc44796f4369b652222cf176b3db6ac70e/public/get-pip.py
ENV PYTHON_GET_PIP_SHA256 96461deced5c2a487ddc65207ec5a9cffeca0d34e7af7ea1afc470ff0d746207

RUN set -eux; \
        \
        wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
        echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum -c -; \
        \
        export PYTHONDONTWRITEBYTECODE=1; \
        \
        python get-pip.py \
                --disable-pip-version-check \
                --no-cache-dir \
                --no-compile \
                "pip==$PYTHON_PIP_VERSION" \
        ; \
        rm -f get-pip.py; \
        \
        pip --version


FROM base as stest


RUN set -eux; \
        apt-get update; \
        apt-get install -y --no-install-recommends git vim; \
        python -m pip uninstall -y setuptools; \
        git clone https://github.com/pypa/setuptools.git /tmp/test_setuptools

WORKDIR /tmp/test_setuptools
COPY script.py patch.diff .
RUN git apply patch.diff

CMD ["/bin/bash"]

As a result, I obtain the following:

without_setuptools_rc_delta=3 without_setuptools_alloc_delta=3
with_setuptools_rc_delta=55 with_setuptools_alloc_delta=28
importlib_rc_delta=55 importlib_alloc_delta=25

Which seems to indicate that (after replacing the "circular references" with weakref.proxy) the increase in rc_delta and alloc_delta of setuptools are roughly equivalent to the ones found by importlib.metadata.entry_points.

@lysnikolaou is replacing the "circular references" (as explained in #3938 (comment)) with weakrefs something the users are expected to do? My other question is: have you investigated importlib.metadata.entry_points (it seems to be the other main responsible for the increase in rc_delta and alloc_delta in setuptools)?