process silence with processes instead of threads

- might help memory issues?
+ fix double slash problem on windows?

app/utils/threading.py

@@ -1,4 +1,5 @@
 import threading
+from multiprocessing import Process, Pipe
 
 
 def background(func):
@@ -12,23 +13,30 @@ def background(func):
     return background_func
 
 
-class ThreadWithReturnValue(threading.Thread):
-    """
-    A thread class that returns a value on join.
 
-    Credit: https://stackoverflow.com/a/6894023
+class ProcessWithReturnValue(Process):
+    """
+    A process class that returns a value on join.
+    Uses a pipe to communicate the return value back to the parent process.
     """
 
     def __init__(
         self, group=None, target=None, name=None, args=(), kwargs={}, Verbose=None
     ):
-        threading.Thread.__init__(self, group, target, name, args, kwargs)
-        self._return = None
+        Process.__init__(self, group=group, target=target, name=name, args=args, kwargs=kwargs)
+        self._parent_conn, self._child_conn = Pipe()
+        self._target = target
+        self._args = args
+        self._kwargs = kwargs
 
     def run(self):
         if self._target is not None:
-            self._return = self._target(*self._args, **self._kwargs)
+            result = self._target(*self._args, **self._kwargs)
+            self._child_conn.send(result)
+        self._child_conn.close()
 
     def join(self, *args):
-        threading.Thread.join(self, *args)
-        return self._return
+        Process.join(self, *args)
+        if self._parent_conn.poll():
+            return self._parent_conn.recv()
+        return None