Get the basic tests passing on 3.11; add it to the CI matrix to see what we see there.

Haven't tried any of the 3.11-specific tests yet.

.github/workflows/ci.yml

@@ -148,7 +148,7 @@ jobs:
         # 3.10 needs more work: dnspython for example doesn't work
         # with it. That means for the bulk of our testing we need to
         # stick to 3.9.
-        python-version: [2.7, pypy-2.7, pypy-3.7, 3.6, 3.7, 3.8, 3.9, '3.10']
+        python-version: [2.7, pypy-2.7, pypy-3.7, 3.6, 3.7, 3.8, 3.9, '3.10', '3.11.0-rc.2']
         # ubuntu-latest is at least 20.04. But this breaks the SSL
         # tests because Ubuntu increased the default OpenSSL
         # strictness.
@@ -178,6 +178,8 @@ jobs:
             python-version: 3.9
           - os: ubuntu-18.04
             python-version: '3.10'
+          - os: ubuntu-18.04
+            python-version: '3.11-rc.2'
     steps:
       - name: checkout
         uses: actions/checkout@v2

docs/changes/1867.feature

+Added preliminary support for Python 3.11 (rc2 and later).
+
+Some platforms may or may not have binary wheels at this time.
+
+.. important:: Support for legacy versions of Python, including 2.7
+               and 3.6, will be ending soon. The
+               maintenance burden has become too great and the
+               maintainer's time is too limited.
+
+               Ideally, there will be a release of gevent compatible
+               with a final release of greenlet 2.0 that still
+               supports those legacy versions, but that may not be
+               possible; this may be the final release to support them.

src/gevent/_compat.py

@@ -19,6 +19,7 @@ PY36 = sys.version_info[:2] >= (3, 6)
 PY37 = sys.version_info[:2] >= (3, 7)
 PY38 = sys.version_info[:2] >= (3, 8)
 PY39 = sys.version_info[:2] >= (3, 9)
+PY311 = sys.version_info[:2] >= (3, 11)
 PYPY = hasattr(sys, 'pypy_version_info')
 WIN = sys.platform.startswith("win")
 LINUX = sys.platform.startswith('linux')

src/gevent/greenlet.py

@@ -375,7 +375,7 @@ class Greenlet(greenlet):
     @property
     def loop(self):
         # needed by killall
-        hub = get_my_hub(self) # type:SwitchOutGreenletWithLoop pylint:disable=undefined-variable
+        hub = get_my_hub(self) # pylint:disable=undefined-variable
         return hub.loop
 
     def __nonzero__(self):
@@ -619,7 +619,7 @@ class Greenlet(greenlet):
         """Schedule the greenlet to run in this loop iteration"""
         if self._start_event is None:
             _call_spawn_callbacks(self)
-            hub = get_my_hub(self) # type:SwitchOutGreenletWithLoop pylint:disable=undefined-variable
+            hub = get_my_hub(self) # pylint:disable=undefined-variable
             self._start_event = hub.loop.run_callback(self.switch)
 
     def start_later(self, seconds):
@@ -1151,7 +1151,7 @@ def killall(greenlets, exception=GreenletExit, block=True, timeout=None):
         Now accepts raw greenlets created by :func:`gevent.spawn_raw`.
     """
 
-    need_killed = [] # type: list
+    need_killed = []
     for glet in greenlets:
         # Quick pass through to prevent any greenlet from
         # actually being switched to if it hasn't already.

src/gevent/socket.py

@@ -14,6 +14,7 @@ as well as the constants from the :mod:`socket` module are imported into this mo
 # pylint: disable=undefined-variable
 
 from gevent._compat import PY3
+from gevent._compat import PY311
 from gevent._compat import exc_clear
 from gevent._util import copy_globals
 
@@ -59,9 +60,9 @@ except AttributeError:
     _GLOBAL_DEFAULT_TIMEOUT = object()
 
 
-def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=None):
+def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=None, **kwargs):
     """
-    create_connection(address, timeout=None, source_address=None) -> socket
+    create_connection(address, timeout=None, source_address=None, *, all_errors=False) -> socket
 
     Connect to *address* and return the :class:`gevent.socket.socket`
     object.
@@ -80,9 +81,18 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=N
         If the host part of the address includes an IPv6 scope ID,
         it will be used instead of ignored, if the platform supplies
         :func:`socket.inet_pton`.
+    .. versionchanged:: NEXT
+        Add the *all_errors* argument. This only has meaning on Python 3.11;
+        it is a programming error to pass it on earlier versions.
     """
+    all_errors = False
+    if PY311:
+        all_errors = kwargs.pop('all_errors', False)
+    if kwargs:
+        raise TypeError("Too many keyword arguments to create_connection", kwargs)
 
     host, port = address
+    exceptions = []
     # getaddrinfo is documented as returning a list, but our interface
     # is pluggable, so be sure it does.
     addrs = list(getaddrinfo(host, port, 0, SOCK_STREAM))
@@ -99,12 +109,25 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=N
             if source_address:
                 sock.bind(source_address)
             sock.connect(sa)
-        except error:
+
+        except error as exc:
+            if not all_errors:
+                exceptions = [exc] # raise only the last error
+            else:
+                exceptions.append(exc)
+            del exc # cycle
             if sock is not None:
                 sock.close()
             sock = None
             if res is addrs[-1]:
-                raise
+                if not all_errors:
+                    del exceptions[:]
+                    raise
+                try:
+                    raise ExceptionGroup("create_connection failed", exceptions)
+                finally:
+                    # Break explicitly a reference cycle
+                    del exceptions[:]
             # without exc_clear(), if connect() fails once, the socket
             # is referenced by the frame in exc_info and the next
             # bind() fails (see test__socket.TestCreateConnection)
@@ -122,6 +145,8 @@ def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT, source_address=N
             sock = None
             raise
         else:
+            # break reference cycles
+            del exceptions[:]
             try:
                 return sock
             finally:

src/gevent/testing/testcase.py

@@ -431,9 +431,12 @@ class TestCase(TestCaseMetaClass("NewBase",
             if hasattr(sig, 'keywords'): # the old version
                 self.assertEqual(sig.keywords, gevent_sig.keywords, func_name)
             else:
-                # The new hotness
-                self.assertEqual(sig.kwonlyargs, gevent_sig.kwonlyargs)
-                self.assertEqual(sig.kwonlydefaults, gevent_sig.kwonlydefaults)
+                # The new hotness. Unfortunately, we can't actually check these things
+                # until we drop Python 2 support from the shared code. The only known place
+                # this is a problem is python 3.11 socket.create_connection(), which we manually
+                # ignore. So the checks all pass as is.
+                self.assertEqual(sig.kwonlyargs, gevent_sig.kwonlyargs, func_name)
+                self.assertEqual(sig.kwonlydefaults, gevent_sig.kwonlydefaults, func_name)
             # Should deal with others: https://docs.python.org/3/library/inspect.html#inspect.getfullargspec
 
     def assertEqualFlakyRaceCondition(self, a, b):

src/gevent/tests/test__socket.py

@@ -581,6 +581,10 @@ class TestFunctions(greentest.TestCase):
             exclude.append('gethostbyname')
             exclude.append('gethostbyname_ex')
             exclude.append('gethostbyaddr')
+        if sys.version_info[:2] == (3, 11):
+            # Be careful not to exclude this on 3.12, etc, in case of
+            # more changes.
+            exclude.append('create_connection')
         self.assertMonkeyPatchedFuncSignatures('socket', exclude=exclude)
 
     def test_resolve_ipv6_scope_id(self):