I've got 32 snapshots in a 21GB subvolume with 3189 directories and 2077439 files. The 24 hour diff between snapshots is only about 5MB. The hourly diff between snapshots is about 160-320KB.
When I start deleting some of the hourly snapshots, the memory usage goes up to at least 2GB (and then the VM runs out of memory). If I add additional memory it can survive but with high disk I/O and a lot of blocked processes. I've created a sanitised btrfs-image of it (with unsanitised snapshot paths) and can reproduce the out of memory condition with a 1GB Ubuntu 16.04 rescue VM (see attached screenshots). Could someone restore the image and investigate why this behaviour occurs? -- Simon Arlott
