linux - What alternative is there to Nginx that supports http keep-alive between backends?

I recently asked a question about how to keep a backend connection persistent using Nginx, but found out it wasn't possible anyway,

It is an HTTP/1.0 proxy without the ability for keep-alive requests yet. (As a result, backend connections are created and destroyed on every request.)

It works all fine right now (since the connection between client and Nginx is kept alive and the result is simply the same), but I don't want to establish a new connection every single time a new request is received ,even if it's on a unix domain socket.

So, what software (preferably open-source and not too tedious to configure) do you recommend to accomplish that such connections ?