Reverted parallelism workaround

app.py

@@ -820,7 +820,7 @@ def get_reply(response, username = None, histories = {}, in_stepsize = 2.56, in_
     num_iterations = int(in_num_iterations)
     top_k = int(in_top_k)
     if response.endswith(("bye", "Bye", "bye.", "Bye.", "bye!", "Bye!")):
-        del histories[username]
+        histories[username] = None
         return "<div class='chatbot'>Chatbot restarted</div>", histories
     history = histories.get(username, None)
     convo_hist = (history if history != None else "How are you?<|endoftext|>") + response + eot_token
@@ -877,7 +877,7 @@ def get_reply(response, username = None, histories = {}, in_stepsize = 2.56, in_
             convo_hist = eot_token.join(convo_hist_split)
 
         except:
-            del histories[username]
+            histories[username] = None
             return "<div class='chatbot'>Error occured, chatbot restarted</div>", histories
     histories[username] = convo_hist
     return html, histories