Performance plateau when keepalives enabled
mdounin at mdounin.ru
Tue Mar 9 01:05:36 MSK 2010
On Mon, Mar 08, 2010 at 11:30:52AM -0500, powderhound wrote:
> When I run the benchmark with keepalive_timeout 65, nginx is
> very slow (5-20 seconds delay) to accept new connections as soon
> as it reaches 1500 concurrent connections. It plateaus here: it
> completes all the requests but it never exceeds approximately
> 1500 concurrent connections.
> Is this normal? Everywhere I read tells me to leave keepalive
> on and it shouldn't make any difference in nginx. So is this a
> keepalive problem, or a problem handling >1500 concurrent
> connections? What should I look at to fix it?
Most likely you hit some network-related limit of your OS or some
firewall inbetween. Check if firewalls have enough number of
state entries, your OS isn't limited by number of sockets, network
buffers and so on.
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