fix ci error (#1921)

* fix ci error

* fix ci error

* add comments

* add comments

.github/workflows/test_qlib_from_pip.yml

@@ -38,9 +38,13 @@ jobs:
       run: |
         python -m pip install pywinpty --only-binary=:all:
 
+    # # joblib was released on 2025-05-04 with version 1.5.0, in which _backend_args was removed and replaced by _backend_kwargs.
+    # This change caused the application to fail, so the version of joblib is restricted here. 
+    # This restriction will be removed in the next release. The current qlib version is: 0.9.6
     - name: Qlib installation test
       run: |
         python -m pip install pyqlib
+        python -m pip install "joblib<=1.4.2"
 
     - name: Install Lightgbm for MacOS
       if: ${{ matrix.os == 'macos-13' || matrix.os == 'macos-14' || matrix.os == 'macos-15' }}

qlib/utils/paral.py

@@ -6,6 +6,7 @@ from functools import partial
 from threading import Thread
 from typing import Callable, Text, Union
 
+import joblib
 from joblib import Parallel, delayed
 from joblib._parallel_backends import MultiprocessingBackend
 import pandas as pd
@@ -21,7 +22,12 @@ class ParallelExt(Parallel):
         maxtasksperchild = kwargs.pop("maxtasksperchild", None)
         super(ParallelExt, self).__init__(*args, **kwargs)
         if isinstance(self._backend, MultiprocessingBackend):
-            self._backend_args["maxtasksperchild"] = maxtasksperchild
+            # 2025-05-04 joblib released version 1.5.0, in which _backend_args was removed and replaced by _backend_kwargs.
+            # Ref: https://github.com/joblib/joblib/pull/1525/files#diff-e4dff8042ce45b443faf49605b75a58df35b8c195978d4a57f4afa695b406bdc
+            if joblib.__version__ < "1.5.0":
+                self._backend_args["maxtasksperchild"] = maxtasksperchild  # pylint: disable=E1101
+            else:
+                self._backend_kwargs["maxtasksperchild"] = maxtasksperchild  # pylint: disable=E1101
 
 
 def datetime_groupby_apply(