I have a per-user DB architecture like so:
There is around 200 user DBs and each has a continuous replication link to the master couch. ( All within the same couch instance) The problem is the CPU usage at any given time is always close to 100%.
The DBs are idle, so no data is getting written/read from them.There's only a few KB of data per DB so I don't think the load is an issue at this point. The master DB size is less than 10 MB.
How can I go about debugging this performance issue?
You should have a look at https://github.com/redgeoff/spiegel - it's a tool to handle many CouchDB replications in a scalable way. Basically it achieves that by listening to the _global_changes endpoint and creating replications only when needed.
In recent CouchDB versions (2.1.0+), the replicator has been improved, but I think for replicating per-user databases it still makes sense to use an external mechanism like Spiegel to manage the number of active replications.
Just as a reminder, there are some security flaws in CouchDB 2.1.0 and you might need to upgrade to 2.1.1. Maybe you've been hacked like this one.
