FIX: Set force=True in multiprocessing.set_start_method('forkserver')

from pytorch/pytorch#3492 (comment)

Author: sebastientourbier

run.py

@@ -43,7 +43,7 @@
 warnings.filterwarnings("ignore", message="numpy.ufunc size changed")
 
 # Set forkserver mode to enable a hard-limited memory-scope
-multiprocessing.set_start_method('forkserver')
+multiprocessing.set_start_method('forkserver', force=True)
 
 
 def report_usage(event_category, event_action, event_label, verbose=False):