Performance issues in group chats

[cfdp]

The users are complaining that the chat gets slow after a group chat with many users has been running for a while (> 30 mins).

It is reported that it takes a long time before text entered in the message field is displayed in the chat stream after sending it to the server. Sometimes the users are even disconnected including the administrator, rendering the chat useless. It has been reported that this typically happens when banned users try to access the chat.

The following needs to be done:

• Reproduce the issue
• Analyze the way functions involved in synchronizing the chat messages and identify the culprits
• Check for memory leaks front end and back end
• Check if banned users connecting again causes problems
• Come up with suggestions for optimizations.

Note that if the "Chat history" feature is enabled, the entire contents of the chat history of the chat room is synched between all users.

[benjamin-dk]

When setting up a group chat and adding two users (one on Windows 8, Edge 11, the other on Android, Chrome) I managed to reproduce significant lagging in the synchronization of the messages between the users.

It happened after sending large messages back and forth for a couple of minutes, and turning the mobile connection on and off on the Android device to simulate an unstable connection. Sometimes it would take 3-6 seconds before the message was synced. It also seemed that messages were not synced immediately to "sleeping windows" (ie. tabs not in focus). When the window comes into focus the messages are synced.