how to limit concurrent uptream requests

[meto]

There is a module for that: http://wiki.nginx.org/Nginx3rdPartyModules#EY_Balancer_Module

But, personally i haven't tried it. Some time ago i used nginx+haproxy for queue handling.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,4562,4567#msg-4567