Fix multiprocessing fork warnings (Python 3.13, Linux) by setting spawn method early

Author: PierreRaybaut

datalab/__init__.py

@@ -11,8 +11,19 @@
 .. _PlotPyStack: https://github.com/PlotPyStack
 """
 
+import multiprocessing
 import os
 
+# Set multiprocessing start method to 'spawn' early to avoid fork-related warnings
+# on Linux systems when using Qt and multithreading. This must be done before
+# any multiprocessing.Pool is created.
+try:
+    multiprocessing.set_start_method("spawn")
+except RuntimeError:
+    # This exception is raised if the method is already set (this may happen because
+    # this module is imported more than once, e.g. when running tests)
+    pass
+
 __version__ = "0.21.0"
 __docurl__ = __homeurl__ = "https://datalab-platform.com/"
 __supporturl__ = "https://github.com/DataLab-Platform/DataLab/issues/new/choose"