Arch Linux

Description:
meson can be made to start up faster with a tweak to how it is packaged.

The meson package uses `setup.py install` to install, as recommended by the Python package guidelines:
https://wiki.archlinux.org/index.php/Python_package_guidelines#Installation_methods

This installation method creates an entry point (/usr/bin/meson) which looks like this:

----------
#!/usr/bin/python
# EASY-INSTALL-ENTRY-SCRIPT: 'meson==0.54.1','console_scripts','meson'
__requires__ = 'meson==0.54.1'
import re
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])
sys.exit(
load_entry_point('meson==0.54.1', 'console_scripts', 'meson')()
)
----------

Specifically, it imports the `pkg_resources` package which has a big memory and time overhead.
The issues with `pkg_resources` are discussed here: https://github.com/pypa/setuptools/issues/510
That issue is closed with a recommendation to use the `pip install` installation method instead,
which the package guidelines currently discourage in favor of the setuptools method. The pip
method generates the following entry point:

----------
#!/usr/bin/python
# -*- coding: utf-8 -*-
import re
import sys
from mesonbuild.mesonmain import main
if __name__ == '__main__':
sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
sys.exit(main())
----------

Note that this doesn't import `pkg_resources`.

On my computer, with the setuptools method `meson --version` takes 390ms, with the pip method it
takes 247ms, a significant difference for a command which is run often.

BTW, this issue affects all Python executables installed in this way, with the same fixed overhead,
so might be desirable to discuss in the context of the entire Python package guidelines.

Additional info:
* package version(s)
meson 0.54.1-1

* link to upstream bug report, if any
There is some ongoing discussion here: https://github.com/mesonbuild/meson/pull/6829#pullrequestreview-400775558

Steps to reproduce:

For the setuptools method, I used the 0.54.1-1 PKGBUILD.

For the pip method, I changed the PKGBUILD as follows:

--- PKGBUILD-old 2020-04-28 01:50:20.962641090 +0300
+++ PKGBUILD 2020-04-28 01:50:29.029399852 +0300
@@ -10,6 +10,7 @@
arch=('any')
license=('Apache')
depends=('python-setuptools' 'ninja')
+makedepends=('python-pip' 'python-wheel')
checkdepends=('gcc-objc' 'vala' 'rust' 'gcc-fortran' 'mono' 'boost' 'qt5-base' 'git' 'cython'
'gtkmm3' 'gtest' 'gmock' 'protobuf' 'wxgtk' 'python-gobject' 'gobject-introspection'
'itstool' 'gtk3' 'java-environment=8' 'gtk-doc' 'llvm' 'clang' 'sdl2' 'graphviz'
@@ -50,7 +51,9 @@

package() {
cd ${pkgname}-${pkgver}
- python setup.py install --root="${pkgdir}" --optimize=1 --skip-build
+ PIP_CONFIG_FILE=/dev/null pip install --isolated --root="$pkgdir" --ignore-installed --no-deps --no-warn-script-location .
+ local site_packages=$(python -c "import site; print(site.getsitepackages()[0])")
+ python -O -m compileall "${pkgdir}${site_packages}/mesonbuild"

install -d "${pkgdir}/usr/share/vim/vimfiles"
cp -rt "${pkgdir}/usr/share/vim/vimfiles" data/syntax-highlighting/vim/*/