Update loky to 3.5.1. (#11341)

Author: trivialfis

ops/conda_env/aarch64_test.yml

@@ -26,7 +26,7 @@ dependencies:
 - awscli
 - numba
 - llvmlite
-- loky
+- loky>=3.5.1
 - pyarrow
 - pyspark>=3.4.0
 - cloudpickle

ops/conda_env/linux_cpu_test.yml

@@ -34,7 +34,7 @@ dependencies:
 - boto3
 - awscli
 - py-ubjson
-- loky
+- loky>=3.5.1
 - pyarrow
 - protobuf
 - cloudpickle

ops/conda_env/macos_cpu_test.yml

@@ -6,8 +6,6 @@ dependencies:
 - pip
 - wheel
 - pyyaml
-- cpplint
-- pylint
 - numpy
 - scipy
 - llvm-openmp
@@ -20,22 +18,17 @@ dependencies:
 - python-graphviz
 - hypothesis
 - astroid
-- sphinx
 - sh
-- recommonmark
-- mock
-- breathe
 - pytest
 - pytest-cov
+- pytest-timeout
 - python-kubernetes
 - urllib3
 - jsonschema
 - boto3
 - awscli
-- loky
+- loky>=3.5.1
 - pyarrow
-- pyspark>=3.4.0
 - cloudpickle
 - pip:
   - setuptools
-  - sphinx_rtd_theme

ops/conda_env/win64_test.yml

@@ -16,5 +16,5 @@ dependencies:
 - python-graphviz
 - pip
 - py-ubjson
-- loky
+- loky>=3.5.1
 - pyarrow

tests/python/test_collective.py

@@ -3,7 +3,6 @@
 
 import numpy as np
 import pytest
-from loky import get_reusable_executor
 
 import xgboost as xgb
 from xgboost import RabitTracker, build_info, federated
@@ -25,10 +24,13 @@ def run_rabit_worker(rabit_env: dict, world_size: int) -> int:
 
 @pytest.mark.skipif(**tm.no_loky())
 def test_rabit_communicator() -> None:
+    from loky import get_reusable_executor
+
     world_size = 2
     tracker = RabitTracker(host_ip="127.0.0.1", n_workers=world_size)
     tracker.start()
     workers = []
+
     with get_reusable_executor(max_workers=world_size) as pool:
         for _ in range(world_size):
             worker = pool.submit(
@@ -60,6 +62,8 @@ def run_federated_worker(port: int, world_size: int, rank: int) -> int:
 @pytest.mark.skipif(**tm.skip_win())
 @pytest.mark.skipif(**tm.no_loky())
 def test_federated_communicator() -> None:
+    from loky import get_reusable_executor
+
     if not build_info()["USE_FEDERATED"]:
         pytest.skip("XGBoost not built with federated learning enabled")