Add `join_threads()` (#10086)

utils/__init__.py

@@ -37,6 +37,16 @@ def threaded(func):
     return wrapper
 
 
+def join_threads(verbose=False):
+    # Join all daemon threads, i.e. atexit.register(lambda: join_threads())
+    main_thread = threading.current_thread()
+    for t in threading.enumerate():
+        if t is not main_thread:
+            if verbose:
+                print(f'Joining thread {t.name}')
+            t.join()
+
+
 def notebook_init(verbose=True):
     # Check system software and hardware
     print('Checking setup...')