Bump minimum Python to 3.11, update linting, drop dead branches (#1553)

- requires-python = ">=3.11"; drop Python 3.10 from CI matrices
- remove code paths that only existed to support Python < 3.11:

Dropping 3.10 was done September of last year, so we are in schedule for
this to be merged just one year after and a bit before the release of
3.15, and just about when Python 3.10 will drop out out security-only
fixes.

note, 3.10 is also the first version that was released 12 month after
it's predecessor, before that it was 18 month.

---  

IPython is already 3.11+, and this will drop quite a number of CI items
to make the CI time bearable, until we start enabling 3.15 that will be
out in about a month.

Author: minrk

.github/workflows/ci.yml

@@ -26,7 +26,6 @@ jobs:
           - qt5
           - qt6
         python-version:
-          - "3.10"
           - "3.11"
           - "3.12"
           - "3.13"
@@ -153,7 +152,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        python-version: ["3.10"]
+        python-version: ["3.11"]
     steps:
       - name: Checkout
         uses: actions/checkout@v7
@@ -183,7 +182,7 @@ jobs:
 
       - uses: actions/setup-python@v7
         with:
-          python-version: "3.10"
+          python-version: "3.11"
 
       - name: Base Setup
         uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1

.pre-commit-config.yaml

@@ -73,7 +73,6 @@ repos:
         additional_dependencies:
           - "pyyaml"
           - "packaging"
-          - "tomli; python_version < '3.11'"
 
   - repo: https://github.com/adamchainz/blacken-docs
     rev: "1.20.0"

ipykernel/kernelbase.py

@@ -551,24 +551,14 @@ def schedule_next():
         # begin polling the eventloop
         schedule_next()
 
-    async def _create_control_lock(self):
-        # This can be removed when minimum python increases to 3.10
-        self._control_lock = asyncio.Lock()
-
     def start(self):
         """register dispatchers for streams"""
         self.io_loop = ioloop.IOLoop.current()
 
         if self.control_stream:
             self.control_stream.on_recv(self.dispatch_control, copy=False)
 
-        if self.control_thread and sys.version_info < (3, 10):
-            # Before Python 3.10 we need to ensure the _control_lock is created in the
-            # thread that uses it. When our minimum python is 3.10 we can remove this
-            # and always use the else below, or just assign it where it is declared.
-            self.control_thread.io_loop.add_callback(self._create_control_lock)
-        else:
-            self._control_lock = asyncio.Lock()
+        self._control_lock = asyncio.Lock()
 
         if self.shell_stream:
             if self.shell_channel_thread:

ipykernel/kernelspec.py

@@ -174,7 +174,7 @@ def install(
     python_arguments = None
 
     # addresses the debugger warning from debugpy about frozen modules
-    if sys.version_info >= (3, 11) and platform.python_implementation() == "CPython":
+    if platform.python_implementation() == "CPython":
         if not frozen_modules:
             # disable frozen modules
             python_arguments = ["-Xfrozen_modules=off"]

ipykernel/utils.py

@@ -3,11 +3,10 @@
 from __future__ import annotations
 
 import asyncio
-import sys
 import typing as t
 from collections.abc import Mapping
 from contextvars import copy_context
-from functools import partial, wraps
+from functools import wraps
 
 if t.TYPE_CHECKING:
     from collections.abc import Callable
@@ -46,36 +45,13 @@ def _async_in_context(
 ) -> Callable[..., t.Coroutine[T, U, V]]:
     """
     Wrapper to run a coroutine in a persistent ContextVar Context.
-
-    Backports asyncio.create_task(context=...) behavior from Python 3.11
     """
     if context is None:
         context = copy_context()
 
-    if sys.version_info >= (3, 11):
-
-        @wraps(f)
-        async def run_in_context(*args, **kwargs):
-            coro = f(*args, **kwargs)
-            return await asyncio.create_task(coro, context=context)
-
-        return run_in_context
-
-    # don't need this backport when we require 3.11
-    # context_holder so we have a modifiable container for later calls
-    context_holder = [context]  # type: ignore[unreachable]
-
-    async def preserve_context(f, *args, **kwargs):
-        """call a coroutine, preserving the context after it is called"""
-        try:
-            return await f(*args, **kwargs)
-        finally:
-            # persist changes to the context for future calls
-            context_holder[0] = copy_context()
-
     @wraps(f)
-    async def run_in_context_pre311(*args, **kwargs):
-        ctx = context_holder[0]
-        return await ctx.run(partial(asyncio.create_task, preserve_context(f, *args, **kwargs)))
+    async def run_in_context(*args, **kwargs):
+        coro = f(*args, **kwargs)
+        return await asyncio.create_task(coro, context=context)
 
-    return run_in_context_pre311
+    return run_in_context

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.11"
 dependencies = [
     "debugpy>=1.6.5",
     "ipython>=7.23.1",

scripts/check_mypy_deps.py

@@ -8,11 +8,7 @@
 from __future__ import annotations
 
 import sys
-
-try:
-    import tomllib
-except ImportError:
-    import tomli as tomllib  # type: ignore[no-reuse-def]
+import tomllib
 
 import yaml
 from packaging.requirements import Requirement

tests/test_eventloop.py

@@ -107,10 +107,6 @@ def test_cocoa_loop(kernel):
 def test_qt_enable_gui(gui, kernel, capsys):
     if os.getenv("GITHUB_ACTIONS", None) == "true" and gui == "qt5":
         pytest.skip("Qt5 and GitHub action crash CPython")
-    if gui == "qt6" and sys.version_info < (3, 10):
-        pytest.skip(
-            "qt6 fails on 3.9 with AttributeError: module 'PySide6.QtPrintSupport' has no attribute 'QApplication'"
-        )
     if sys.platform == "linux" and gui == "qt6" and os.getenv("GITHUB_ACTIONS", None) == "true":
         pytest.skip("qt6 fails on github CI with missing libEGL.so.1")
     enable_gui(gui, kernel)

tests/test_kernelspec.py

@@ -154,7 +154,7 @@ def test_install_env(tmp_path, env):
         assert "env" not in spec
 
 
-@pytest.mark.skipif(sys.version_info < (3, 11) or not is_cpython, reason="requires cPython 3.11")
+@pytest.mark.skipif(not is_cpython, reason="requires CPython")
 def test_install_frozen_modules_on():
     system_jupyter_dir = tempfile.mkdtemp()
 
@@ -168,7 +168,7 @@ def test_install_frozen_modules_on():
     assert "-Xfrozen_modules=off" not in spec["argv"]
 
 
-@pytest.mark.skipif(sys.version_info < (3, 11) or not is_cpython, reason="requires cPython 3.11")
+@pytest.mark.skipif(not is_cpython, reason="requires CPython")
 def test_install_frozen_modules_off():
     system_jupyter_dir = tempfile.mkdtemp()
 
@@ -182,13 +182,9 @@ def test_install_frozen_modules_off():
     assert spec["argv"][1] == "-Xfrozen_modules=off"
 
 
-@pytest.mark.skipif(
-    sys.version_info >= (3, 11) or is_cpython,
-    reason="checks versions older than 3.11 and other Python implementations",
-)
+@pytest.mark.skipif(is_cpython, reason="checks non-CPython implementations")
 def test_install_frozen_modules_no_op():
-    # ensure we do not add add Xfrozen_modules on older Python versions
-    # (although cPython does not error out on unknown X options as of 3.8)
+    # ensure we do not add -Xfrozen_modules on non-CPython implementations
     system_jupyter_dir = tempfile.mkdtemp()
 
     with mock.patch("jupyter_client.kernelspec.SYSTEM_JUPYTER_PATH", [system_jupyter_dir]):