Downloading feeds stopped for several hours this afternoon, but everything is working fine right now.
The problem was quite interesting:
- we have an SQL query that brings back N feeds to download, where N is the number of threads,
- but if a feed has no "subscribers" -- i.e. one or more accounts listening to it -- we basically do nothing, including updating the next check date
What was happening was the query was bringing back the same N feeds every time, all with nothing to do. There's probably two or three fixes need to make this work right, but the simplest (but not long term) solution is to remove the LIMIT N from the SQL query.