I've migrated a Rails app that I didn't build to a new server for a
customer. Now there are certain pages which are timing out almost
exactly at 10 seconds. They do not report an error, they just go to a
blank white page.
I know they're timing out and not erring out b/c when I reduce the size
of the query by limit and the page loads fine every time. Also this is
happening with file uploads. Small files upload fine, larger one's that
require processing go to a white screen at 10 seconds.
This sounds like your load balancer (the thing that proxies requests
to your mongrels) giving up.