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Cause of performance bottleneck on my server ?
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Cause of performance bottleneck on my server ?

SaahibSaahib Host Rep, Veteran

Hi,
I have a server with nginx as reverse proxy for apache, it is running rather average (not so good custom php app). With nginx and other tweaks, it was able to server about 5000-6000 request easily. But suddenly from last few days, as soon as reaches 1000 req/sec , site starts to crawl and becomes unresponsive (with random 502 error).
However, thing is that there are no server load, no disk load or anything. But on nginx error log, I see "request timed out from upstream" (ie. apache) but there are no error logs on apache.

Have done lot more than to diagnose , now I am out of ideas, can't figure out what to look, if script to be blamed then there should be spike in server load.

What I see that when it crosses 1000+ req/sec, apache simply stops feeding nginx requests.. but without any error logs in apache, I am clueless.

Can you suggest your checklist in such situation to resolve issue other than hardware upgrade or script optimization (php) ?

Comments

  • exception0x876exception0x876 Member, Host Rep, LIR

    Do you have keepalive enabled on apache? If yes then you might want to disable it since apache might be simply running out of available processes (yet it is weird that there are no error logs).

  • SaahibSaahib Host Rep, Veteran
    edited April 2017

    @exception0x876 said:
    Do you have keepalive enabled on apache? If yes then you might want to disable it since apache might be simply running out of available processes (yet it is weird that there are no error logs).

    Already disabled when had first done tweak for this server.

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