Today thumbor in production filled up its disks with error logs in the form of "Too many open files", this is similar to what we've seen in T156913: Thumbor keeps too many file descriptors open though the leak appears to be pipes only.
I've restarted all instances on thumbor1002 and left thumbor1001 as is for now for inspection. It looks like only two instances on 1001 have hit the limit now (8836 / 8837) but all instances leak. For example 8827 is approaching its fd limit, I've captured some earlier log output in P4926. The errors seems related either not finding a suitable engine (recurring, seems to be normal) or some swift-related 401 / Unauthorized while PUTting thumbs. I _think_ the unauthorized might be related to having long-running swift tokens that eventually expire and the need to get authorized tokens again.