Add InterpreterPoolExecutor support for Python 3.14+

Co-authored-by: akhmerov <2069677+akhmerov@users.noreply.github.com>

Author: Copilot

adaptive/_types.py

@@ -2,7 +2,8 @@
 # Workaround described in https://github.com/agronholm/typeguard/issues/456
 
 import concurrent.futures as concurrent
-from typing import TypeAlias
+import sys
+from typing import TYPE_CHECKING, TypeAlias
 
 import distributed
 import ipyparallel
@@ -11,14 +12,31 @@
 
 from adaptive.utils import SequentialExecutor
 
-ExecutorTypes: TypeAlias = (
-    concurrent.ProcessPoolExecutor
-    | concurrent.ThreadPoolExecutor
-    | SequentialExecutor
-    | loky.reusable_executor._ReusablePoolExecutor
-    | distributed.Client
-    | distributed.cfexecutor.ClientExecutor
-    | mpi4py.futures.MPIPoolExecutor
-    | ipyparallel.Client
-    | ipyparallel.client.view.ViewExecutor
-)
+# For Python 3.14+, include InterpreterPoolExecutor in the type alias
+if sys.version_info >= (3, 14):
+    if TYPE_CHECKING:
+        # Type checkers will see this when checking Python 3.14+ code
+        ExecutorTypes: TypeAlias = (
+            concurrent.ProcessPoolExecutor
+            | concurrent.ThreadPoolExecutor
+            | concurrent.InterpreterPoolExecutor  # type: ignore[attr-defined]
+            | SequentialExecutor
+            | loky.reusable_executor._ReusablePoolExecutor
+            | distributed.Client
+            | distributed.cfexecutor.ClientExecutor
+            | mpi4py.futures.MPIPoolExecutor
+            | ipyparallel.Client
+            | ipyparallel.client.view.ViewExecutor
+        )
+else:
+    ExecutorTypes: TypeAlias = (
+        concurrent.ProcessPoolExecutor
+        | concurrent.ThreadPoolExecutor
+        | SequentialExecutor
+        | loky.reusable_executor._ReusablePoolExecutor
+        | distributed.Client
+        | distributed.cfexecutor.ClientExecutor
+        | mpi4py.futures.MPIPoolExecutor
+        | ipyparallel.Client
+        | ipyparallel.client.view.ViewExecutor
+    )

adaptive/runner.py

@@ -44,7 +44,14 @@
 
 
 # -- Runner definitions
-if platform.system() == "Linux":
+# Check if InterpreterPoolExecutor is available (Python 3.14+)
+_has_interpreter_pool = hasattr(concurrent, "InterpreterPoolExecutor")
+
+if _has_interpreter_pool:
+    # Use InterpreterPoolExecutor for Python 3.14+
+    # It provides better isolation and performance than ProcessPoolExecutor
+    _default_executor = concurrent.InterpreterPoolExecutor  # type: ignore[misc,attr-defined]
+elif platform.system() == "Linux":
     _default_executor = concurrent.ProcessPoolExecutor  # type: ignore[misc]
 else:
     # On Windows and MacOS functions, the __main__ module must be
@@ -1025,6 +1032,8 @@ def _get_ncores(
         return len(ex.view)
     elif isinstance(ex, concurrent.ProcessPoolExecutor | concurrent.ThreadPoolExecutor):
         return ex._max_workers  # type: ignore[union-attr]
+    elif _has_interpreter_pool and isinstance(ex, concurrent.InterpreterPoolExecutor):  # type: ignore[attr-defined]
+        return ex._max_workers  # type: ignore[union-attr]
     elif isinstance(ex, loky.reusable_executor._ReusablePoolExecutor):
         return ex._max_workers  # type: ignore[union-attr]
     elif isinstance(ex, SequentialExecutor):

adaptive/tests/test_runner.py

@@ -263,3 +263,27 @@ def counting_ask(self, n, tell_pending=True):
     finally:
         # Restore original method
         Learner1D.ask = original_ask
+
+
+def test_interpreter_pool_executor_detection():
+    """Test that InterpreterPoolExecutor is detected and used in Python 3.14+."""
+    import concurrent.futures as concurrent
+    import sys
+
+    from adaptive.runner import _default_executor, _has_interpreter_pool
+
+    if sys.version_info >= (3, 14) and hasattr(concurrent, "InterpreterPoolExecutor"):
+        # On Python 3.14+, InterpreterPoolExecutor should be available and used
+        assert _has_interpreter_pool is True
+        assert _default_executor == concurrent.InterpreterPoolExecutor
+    else:
+        # On older Python versions, it should not be available
+        assert _has_interpreter_pool is False
+        # Should fall back to ProcessPoolExecutor on Linux or loky on others
+        if OPERATING_SYSTEM == "Linux":
+            assert _default_executor == concurrent.ProcessPoolExecutor
+        else:
+            import loky
+
+            assert _default_executor == loky.get_reusable_executor
+