nginx in high concurrency setups

merlin corey merlincorey at
Mon Dec 14 23:16:49 MSK 2009

On Mon, Dec 14, 2009 at 11:16 AM, Dennis J. <dennisml at> wrote:
> Hi,
> I'm currently experimenting how many concurrent connections nginx can
> handle. The problem I'm running into is that for each request I send to the
> server I get a connection in TIME_WAIT state. If I do this using
> benchmarking tools like httperf or ab I quickly seem to hit a ceiling. Once
> the number of TIME_WAIT connections reaches about 16000 the benchmarking
> tools just freeze and I have to wait until that number comes down again.
> What is the reason for these TIME_WAIT connections and how can I get rid of
> them faster? I'm only serving small static files and the delivery is not
> supposed to take longer than say 300ms so any connection that takes longer
> than that can be aborted if that is necessary to make room for new incoming
> connections.
> Does anyone have experience with serving lots of small static requests using
> nginx?
> Regards,
>  Dennis
> _______________________________________________
> nginx mailing list
> nginx at


You will need to tune your OS's TCP and socket settings, I do believe.
 It is dependent on your OS what exactly you must do.

Also, keep in mind, that when you are doing these tests, ideally you
should be sending the test-load from multiple machines that are not
the same machine that is serving.  This is to rule out the
benchmarking program fighting for resources with nginx and to rule out
a single machine's ceilings.


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