My project to test Holster started hitting 100% CPU the other day during peak processing times, so have been doing some investigation. It's not a big server, but Holster shouldn't need the resources it was using and this was a great opportunity to identify what needed improving.

This has led to a few performance improvement releases this week. The first was that the caching radisk was doing was only for the most recent file. This doesn't do very much when keys come in randomly for different files, and each key caches a new file. Holster is currently not designed to hold heaps of data, so it now just caches all files, which was a big improvement as reading from disk is expensive.

Next was improving the client throttling to use an actual processing queue. It previously tried to throttle with timeouts but this just caused messages to build up later. The advantage of a processing queue is that you can also return an error if the queue gets too long, because there is probably something wrong with your Holster queries if this happens (ie requesting too much data.)

Lastly the Holster website got an update! It now has a nice little visualization of connected clients.