Proxy upstream implementation with persistent connections?

[Brian Pane]

Has anyone made a module that supports keep-alive connections for HTTP
upstreams?

I'm working on an application where each request to nginx will result
in multiple subrequests to an upstream HTTP server, and the network
latency between nginx and the upstream server could be large (tens of
milliseconds), so reusing a connection to the upstream server would
help quite a bit.

Thanks,
-Brian