Could not access any of my sites, not even via the cli. Checked my control panel and saw this. VPS memory is set at 400MB, which is where it maxed out. Server load has rarely been above 1.5; now it was at 40, which I have never seen before.
As I said, I couldn't even access the cli, so I had to reboot the server. I now have access, but I don't even know where to begin diagnosing this. Which server process could cause a VPS to use all of its available memory without going over the limit and triggering the stability robot to reboot it? What did I miss?