Maintenance tab is incredibly laggy

[gregorydlogan]

Try setting your server to maintenance mode. Just wait, it'll happen eventually...

It's reflected in the backend immediately, but the UI is very slow to react. 30+ seconds by my count.

[Arnei]

The cause for this seems to lie with the backend. The admin ui backend caches server information for 60 seconds before getting new information, so it can take up to a minute before the admin ui is informed about any changes: https://github.com/opencast/opencast/blob/74b784d5f68b0c8bad7c47b453718b6c5b670799/modules/admin-ui/src/main/java/org/opencastproject/adminui/endpoint/ServerEndpoint.java#L269

Quoting the commit that introduced the caching:

Cache Server Statistics

This add caching to the admin interface's server statistics endpoint to
avoid putting a high load on the database by having this open multiple
times.
(opencast/opencast#2851)

So we probably don't want to remove caching. A higher refresh rate might work, but also increases the risk of overwhelming the database. Alternatively, figuring out why this in particular generates such a high load and make it not do that is probably the ideal, but also more time-consuming approach.

[KatrinIhler]

Just fell over this as well. The old Admin UI also refreshed according to a set interval iirc, but the checkbox could be immediately checked or unchecked by the user (and would then be updated during the next refresh). Can we somehow reproduce this? The way it is now, the user (aka me) is tempted to click multiple times because nothing seems to be happening.