Deprecate loky.

Author: tobiasraabe

.pre-commit-config.yaml

@@ -27,7 +27,7 @@ repos:
     rev: v3.11.0
     hooks:
     -   id: reorder-python-imports
-        args: [--py37-plus, --add-import, 'from __future__ import annotations']
+        args: [--py38-plus, --add-import, 'from __future__ import annotations']
 -   repo: https://github.com/asottile/setup-cfg-fmt
     rev: v2.4.0
     hooks:

CHANGES.md

@@ -7,7 +7,7 @@ releases are available on [PyPI](https://pypi.org/project/pytask-parallel) and
 
 ## 0.4.0 - 2023-xx-xx
 
-- {pull}`62` deprecates Python 3.7.
+- {pull}`62` deprecates Python 3.7 and remove loky.
 
 ## 0.3.1 - 2023-05-27
 

README.md

@@ -30,10 +30,6 @@ $ conda install -c conda-forge pytask-parallel
 
 By default, the plugin uses `concurrent.futures.ProcessPoolExecutor`.
 
-It is also possible to select the executor from loky or `ThreadPoolExecutor` from the
-[concurrent.futures](https://docs.python.org/3/library/concurrent.futures.html) module
-as backends to execute tasks asynchronously.
-
 ## Usage
 
 To parallelize your tasks across many workers, pass an integer greater than 1 or
@@ -65,7 +61,7 @@ You can also set the options in a `pyproject.toml`.
 
 [tool.pytask.ini_options]
 n_workers = 1
-parallel_backend = "processes"  # or loky or threads
+parallel_backend = "processes"  # or threads
 ```
 
 ## Some implementation details

environment.yml

@@ -18,7 +18,6 @@ dependencies:
   # Package dependencies
   - pytask >=0.3
   - cloudpickle
-  - loky
   - pybaum >=0.1.1
 
   # Misc

pyproject.toml

@@ -25,7 +25,7 @@ ignore_errors = true
 
 
 [tool.ruff]
-target-version = "py37"
+target-version = "py38"
 select = ["ALL"]
 fix = true
 extend-ignore = [

setup.cfg

@@ -26,7 +26,6 @@ packages = find:
 install_requires =
     click
     cloudpickle
-    loky
     pybaum>=0.1.1
     pytask>=0.3
 python_requires = >=3.8

src/pytask_parallel/backends.py

@@ -23,7 +23,8 @@ def deserialize_and_run_with_cloudpickle(
 class CloudpickleProcessPoolExecutor(ProcessPoolExecutor):
     """Patches the standard executor to serialize functions with cloudpickle."""
 
-    # The type signature is wrong for version above Py3.7. Fix when 3.7 is deprecated.
+    # The type signature has issues. See https://github.com/python/typeshed/issues/7750
+    # for more information.
     def submit(  # type: ignore[override]
         self, fn: Callable[..., Any], *args: Any, **kwargs: Any  # noqa: ARG002
     ) -> Future[Any]:
@@ -35,39 +36,16 @@ def submit(  # type: ignore[override]
         )
 
 
-try:
-    from loky import get_reusable_executor
+class ParallelBackendChoices(enum.Enum):
+    """Choices for parallel backends."""
 
-except ImportError:
+    PROCESSES = "processes"
+    THREADS = "threads"
 
-    class ParallelBackendChoices(enum.Enum):
-        """Choices for parallel backends."""
 
-        PROCESSES = "processes"
-        THREADS = "threads"
-
-    PARALLEL_BACKENDS = {
-        ParallelBackendChoices.PROCESSES: CloudpickleProcessPoolExecutor,
-        ParallelBackendChoices.THREADS: ThreadPoolExecutor,
-    }
-
-else:
-
-    class ParallelBackendChoices(enum.Enum):  # type: ignore[no-redef]
-        """Choices for parallel backends."""
-
-        PROCESSES = "processes"
-        THREADS = "threads"
-        LOKY = "loky"
-
-    PARALLEL_BACKENDS_DEFAULT = ParallelBackendChoices.PROCESSES
-
-    PARALLEL_BACKENDS = {
-        ParallelBackendChoices.PROCESSES: CloudpickleProcessPoolExecutor,
-        ParallelBackendChoices.THREADS: ThreadPoolExecutor,
-        ParallelBackendChoices.LOKY: (  # type: ignore[attr-defined]
-            get_reusable_executor
-        ),
-    }
+PARALLEL_BACKENDS = {
+    ParallelBackendChoices.PROCESSES: CloudpickleProcessPoolExecutor,
+    ParallelBackendChoices.THREADS: ThreadPoolExecutor,
+}
 
 PARALLEL_BACKENDS_DEFAULT = ParallelBackendChoices.PROCESSES

tests/test_execute.py

@@ -132,7 +132,6 @@ def myfunc():
         backend_name_space = {
             ParallelBackendChoices.PROCESSES: ProcessesNameSpace,
             ParallelBackendChoices.THREADS: DefaultBackendNameSpace,
-            ParallelBackendChoices.LOKY: DefaultBackendNameSpace,
         }[parallel_backend]
 
         future = backend_name_space.pytask_execute_task(session, task)

tox.ini

@@ -7,7 +7,6 @@ usedevelop = true
 [testenv:pytest]
 conda_deps =
     cloudpickle
-    loky
     pytask >=0.3.0
     pytest
     pytest-cov