Add mp_context check

src/spikeinterface/postprocessing/principal_component.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import warnings
+import platform
 from pathlib import Path
 from tqdm.auto import tqdm
 
@@ -418,6 +419,11 @@ def _fit_by_channel_local(self, n_jobs, progress_bar, max_threads_per_process, m
 
         p = self.params
 
+        if mp_context is not None and platform.system() == "Windows":
+            assert mp_context != "fork", "'fork' mp_context not supported on Windows!"
+        elif mp_context == "fork" and platform.system() == "Darwin":
+            warnings.warn('As of Python 3.8 "fork" is no longer considered safe on macOS')
+
         unit_ids = self.sorting_analyzer.unit_ids
         channel_ids = self.sorting_analyzer.channel_ids
         # there is one PCA per channel for independent fit per channel

src/spikeinterface/postprocessing/tests/test_principal_component.py

@@ -25,7 +25,7 @@ def test_multi_processing(self):
         sorting_analyzer = self._prepare_sorting_analyzer(
             format="memory", sparse=False, extension_class=ComputePrincipalComponents
         )
-        sorting_analyzer.compute("principal_components", mode="by_channel_local", n_jobs=2, mp_context="fork")
+        sorting_analyzer.compute("principal_components", mode="by_channel_local", n_jobs=2)
         sorting_analyzer.compute(
             "principal_components", mode="by_channel_local", n_jobs=2, max_threads_per_process=4, mp_context="spawn"
         )