flush the prints in a separate thread

app.py

@@ -41,7 +41,7 @@ class WebPushService():
         - daily_notification_thread (threading.Thread): A thread to send daily notifications.
         """
 
-        # Setting the application instance        
+        # Setting the application instance
         self.app = app
         self.app.add_url_rule('/web-push/regenerate_vapid', view_func=self.regenerate_vapid, methods=['POST'])
 
@@ -156,7 +156,7 @@ class WebPushService():
         except WebPushException as ex:
             now = datetime.datetime.now().isoformat()
             endpoint = subscription_info['endpoint']
-            print(f"{now}: Failed to send push notification for {endpoint} -- {ex}")
+            print(f"{now}: Failed to send push notification for {endpoint} -- {ex}", flush=True)
 
             unsubscribed_msg = '410 Gone'
             if unsubscribed_msg in ex.args[0]:
@@ -166,11 +166,13 @@ class WebPushService():
                 if subscription:
                     db.session.delete(subscription)
                     db.session.commit()
-                    print(f"Committed delete of {subscription_info}")
+                    print(f"Committed delete of {subscription_info}", flush=True)
                 else:
-                    print(f"Could not find subscription at: {endpoint}")
+                    print(f"Could not find subscription at: {endpoint}", flush=True)
             else:
-                print("Wrong error.", ex.args[0])
+                print("Error other than unsubscribed/expired.", ex.args[0], flush=True)
+
+            return False
 
 
     def _send_daily_notifications(self) -> None:
@@ -193,7 +195,7 @@ class WebPushService():
         while True:
             
             now = datetime.datetime.now().isoformat()
-            print(f"{now} - Starting to send subscriptions...")
+            print(f"{now} - Starting to send subscriptions...", flush=True)
 
             # Creating a context for the application to enable database operations
             with self.app.app_context():
@@ -217,7 +219,7 @@ class WebPushService():
                         }
                     }
                     WebPushService._send_push_notification(subscription_info, message, vapid_key)
-                print(f"{now} - Finished sending {len(all_subscriptions)} subscriptions.")
+                print(f"{now} - Finished sending {len(all_subscriptions)} subscriptions.", flush=True)
 
             # Sleeping for 24 hours before sending the next set of notifications
             time.sleep(24 * 60 * 60)
@@ -387,11 +389,11 @@ class WebPushService():
         - If the subscription is not found in the database, an error message is returned with a 404 status code.
         """
 
-        # Retrieving the endpoint from the incoming request        
+        # Retrieving the endpoint from the incoming request
         content = request.json
         endpoint = content['endpoint']
 
-        # Searching for the subscription in the database using the endpoint        
+        # Searching for the subscription in the database using the endpoint
         subscription = Subscription.query.filter_by(endpoint=endpoint).first()
 
         # If the subscription is found, delete it from the database
@@ -406,4 +408,3 @@ class WebPushService():
 
 
 web_push_service = WebPushService(app, "app")
-