Speed up emulated manylinux builds

- don't compile Cython as recommended at https://cython.readthedocs.io/en/latest/src/quickstart/install.html
- don't install test extras we will not need

scripts/releases/make-manylinux

@@ -45,6 +45,11 @@ if [ -n "$GITHUB_ACTIONS" ]; then
         SLOW_BUILD=1
         GEVENTTEST_SKIP_ALL=1
         export GEVENTSETUP_DISABLE_ARES=1
+        # ccache has been seen to have some issues here with too many open files?
+        unset CC
+        unset LDSHARED
+        unset LDCCSHARED
+        unset LDCXXSHARED
     fi
 else
     OPTIMIZATION_FLAGS="-pipe -O3"
@@ -63,6 +68,8 @@ export LDFLAGS="$LIBS"
 # a fallback loop.
 export GEVENT_LOOP="libev-cext"
 
+SEP="~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
+
 if [ -d /gevent -a -d /opt/python ]; then
     # Running inside docker
     # Set a cache directory for pip. This was
@@ -75,13 +82,16 @@ if [ -d /gevent -a -d /opt/python ]; then
     # pip to disable the cache when it detects that the owner doesn't match.
     # The below is an attempt to fix that, taken frob bcrypt. It seems to work on
     # Github Actions.
+    echo $SEP
     if [ -n "$GITHUB_ACTIONS" ]; then
-        echo Adjusting pip cache permissions
+        echo Adjusting pip cache permissions: $(whoami)
         mkdir -p $XDG_CACHE_HOME/pip
         chown -R $(whoami) $XDG_CACHE_HOME
     fi
     ls -ld /cache
     ls -ld /cache/pip
+    echo $SEP
+    echo "Installing Build Deps"
     if [ -e /usr/bin/yum ]; then
         yum -y install libffi-devel
         # Some images/archs (specificaly 2014_aarch64) don't have ccache;
@@ -100,9 +110,12 @@ if [ -d /gevent -a -d /opt/python ]; then
         # the muslinux image
         apk add --no-cache build-base libffi-dev ccache
     fi
+    echo $SEP
 
-    echo Current environment
+    echo  Current environment
+    echo $SEP
     env | sort
+    echo $SEP
 
     mkdir /tmp/build
     cd /tmp/build
@@ -114,12 +127,35 @@ if [ -d /gevent -a -d /opt/python ]; then
     else
         echo Not configuring c-ares because it is disabled
     fi
+    echo $SEP
     rm -rf /gevent/wheelhouse
     mkdir /gevent/wheelhouse
     OPATH="$PATH"
     which auditwheel
-    for variant in `ls -d /opt/python/cp{310,38,39,311,312}*`; do
+    # June 2023: 3.8, 3.9, and 3.10 are in security-fix only mode, ending support in
+    # 2024, 2025, and 2026, respectively. Only 3.11+ are in active support mode.
+    # Building a variant in emulation takes at least 9 minutes on Github Actions,
+    # plus many minutes to build the deps (Cython) and then many more minutes to build and
+    # install test dependencies; a complete build for ppc64le with 3.8, 9, 10, 11, and 12
+    # took 1.5 hours. Multiply that times all the SLOW_BUILD images, and you've got a lot of time.
+    #
+    # So, for SLOW_BUILD environments:
+    # - skip security-fix only versions; users still on those versions are the least likely to
+    #   upgrade dependencies
+    # - skip running most tests and installing test extras (which we don't need because we only run
+    #   a tiny subset of tests)
+    echo Possible Builds
+    ls -l /opt/python/
+    for variant in /opt/python/cp{38,39,310,311,312}*; do
+        echo $SEP
         export PATH="$variant/bin:$OPATH"
+        if [ -n "$SLOW_BUILD" ]; then
+            is_security_fix_only=$(python -c 'import sys; print(sys.version_info[:2] < (3, 10))')
+            if [ "$is_security_fix_only" == "True" ]; then
+                echo "Skipping build of $variant"
+                continue
+            fi
+        fi
         echo "Building $variant $(python --version)"
 
         python -mpip install -U pip
@@ -127,14 +163,19 @@ if [ -d /gevent -a -d /opt/python ]; then
         # The downside is that we must install dependencies manually.
         # NOTE: We can't upgrade ``wheel`` because ``auditwheel`` depends on
         # it, and auditwheel is installed in one of these environments.
-        python -m pip install -U 'cython>=3.0b3; python_version < "3.12"' "Cython @ https://github.com/cython/cython/archive/37f4dcdc04547875e2836fda076f5707ec50e579.zip; python_version >= '3.12'"
-        python -mpip install -U cffi 'greenlet >= 2.0.0; python_version < "3.12"' 'greenlet >= 3.0a1; python_version >= "3.12"' setuptools
+        # If there is no Cython binary wheel available, don't try to build one; it takes
+        # forever!
+        time python -m pip install --config-settings='--install-option="--no-cython-compile"' -U 'cython>=3.0b3; python_version < "3.12"' "Cython @ https://github.com/cython/cython/archive/37f4dcdc04547875e2836fda076f5707ec50e579.zip; python_version >= '3.12'"
+        time python -mpip install -U cffi 'greenlet >= 2.0.0; python_version < "3.12"' 'greenlet >= 3.0a1; python_version >= "3.12"' setuptools
+        echo "$variant: Building wheel"
         time (python setup.py bdist_wheel)
         PATH="$OPATH" auditwheel repair dist/gevent*.whl
         cp wheelhouse/gevent*.whl /gevent/wheelhouse
-
-        python -mpip install -U --no-compile `ls dist/gevent*whl`[test]
-        echo 'Installation details'
+        # Install it and its deps to be sure that it can be done; no sense
+        # trying to publish a wheel that can't be installed.
+        time python -mpip install -U --no-compile $(ls dist/gevent*whl)
+        # Basic sanity checks
+        echo "$variant: Installation details"
         python -c 'from __future__ import print_function; import gevent; print(gevent, gevent.__version__)'
         python -c 'from __future__ import print_function; from gevent._compat import get_clock_info; print("clock info", get_clock_info("perf_counter"))'
         python -c 'from __future__ import print_function; import greenlet; print(greenlet, greenlet.__version__)'
@@ -147,6 +188,8 @@ if [ -d /gevent -a -d /opt/python ]; then
         fi
 
         if [ -z "$GEVENTTEST_SKIP_ALL" ]; then
+            # With the test extra
+            time python -mpip install -U --no-compile $(ls dist/gevent*whl)[test]
             python -mgevent.tests --second-chance
         else
             # Allow skipping the bulk of the tests. If we're emulating Arm,
@@ -165,15 +208,17 @@ fi
 # Mount the current directory as /gevent
 # Mount the pip cache directory as /cache
 # `pip cache` requires pip 20.1
+echo $SEP
 echo Setting up caching
 python --version
 python -mpip --version
 LCACHE="$(dirname `python -mpip cache dir`)"
 echo Sharing pip cache at $LCACHE $(ls -ld $LCACHE)
 echo Sharing ccache dir at $HOME/.ccache
-if [ ! -d $HOME/.ccache ]; then
-    mkdir $HOME/.ccache
+if [ ! -d "$HOME/.ccache" ]; then
+    mkdir "$HOME/.ccache"
 fi
+echo $SEP
 # Travis CI and locally we want `-ti`, but github actions doesn't have a TTY, so one
 # or the other of the arguments causes this to fail with 'input device is not a TTY'
 # Pas through whether we're running on github or not to help with caching.

src/gevent/tests/test__core.py

 
 from __future__ import absolute_import, print_function, division
 
+# Important: This file should have no dependencies that are part of the
+# ``test`` extra, because it is sometimes run for quick checks without those
+# installed.
+
 import unittest
 import sys
 import gevent.testing as greentest