High response time at high concurrent connections

[Yichun Zhang (agentzh)]

Hello!

On Fri, Oct 4, 2013 at 7:48 AM, laltin wrote:
> My backend logs show response times generally less than 2ms and with 4
> instances backends can handle 2000 reqs/sec.
> But when I look at nginx logs I see response times around 200ms and i think
> nginx is the main problem with my situation.
>

As I've suggested, use the off-CPU and on-CPU flamegraph tool to check
your loaded Nginx worker processes. It could easily be a configuration
issue or something. Please do that.

See

    https://github.com/agentzh/nginx-systemtap-toolkit#sample-bt

and

    https://github.com/agentzh/nginx-systemtap-toolkit#sample-bt-off-cpu

Also, ensure your Nginx is not flooding your Nginx's error log file,
which is very expensive. If it is, you can also clearly see it in the
flame graphs anyway.

Stop guessing, start tracing! :)

Best regards,
-agentzh