I agree with you in theory, in practice, my experience has been a bit different. Specifically,
1. Since Mongo has a database (or maybe collection now) level lock, doing rebalancing under a heavy write load is impossible.
3. Mongos creates one thread per connection. This means that if you've got to be very careful about the number of clients you start up at any given time (or in total).
1. Since Mongo has a database (or maybe collection now) level lock, doing rebalancing under a heavy write load is impossible.
3. Mongos creates one thread per connection. This means that if you've got to be very careful about the number of clients you start up at any given time (or in total).