Re: postgresql + apache under heavy load - Mailing list pgsql-general

From Alex Madon
Subject Re: postgresql + apache under heavy load
Date
Msg-id 400EC975.4050307@bestlinuxjobs.com
Whole thread Raw
In response to Re: postgresql + apache under heavy load  ("scott.marlowe" <scott.marlowe@ihs.com>)
Responses Re: postgresql + apache under heavy load  ("scott.marlowe" <scott.marlowe@ihs.com>)
Re: postgresql + apache under heavy load  (Robert Treat <xzilla@users.sourceforge.net>)
List pgsql-general
Hello Scott,
Thank you for your answer.

>I'm not familiar with DBX.  Is that connection pooling or what?
>
>
I could not find this information, sorry.

>Are you SURE all your memory is in use?  What exactly does top say about
>things like cached and buff memory (I'm assuming you're on linux, any
>differences in top on another OS would be minor.)  If the kernel still
>shows a fair bit of cached and buff memory, your memory is not getting all
>used up.
>
Well my xosview show that caching begin at a concurrency of 40.
At 80 my cache begins to be filled completely, so machine having big
problems.

>>If I increases to
>>ab -n 1000 -c 100 http://localsite/testscript
>>I get this memory problem.
>>
>>
>
>Where's the break point?  Just wondering.  Does it show up at 20, 40, 60,
>80, or only at 100?  If so, that's really not bad.
>
 Here is some results (I kept -n 100 an just vraied the -c option)
--c 1
Failed requests:        0
Time per request:       322.096 [ms] (mean, across all concurrent requests)

-c 2
Failed requests:        0
Time per request:       374.220 [ms] (mean, across all concurrent requests)

-c 10
Failed requests:        68
 (Connect: 0, Length: 68, Exceptions: 0)
Time per request:       314.779 [ms] (mean, across all concurrent requests)

-c 20
Failed requests:        68
Time per request:       369.290 [ms] (mean, across all concurrent requests)

-c 30
Failed requests:        43
Time per request:       441.947 [ms] (mean, across all concurrent requests)

=====Here begins caching to disk====

-c 40
Failed requests:        65
Time per request:       528.829 [ms] (mean, across all concurrent requests)

-c 50
Failed requests:        66
Time per request:       993.674 [ms] (mean, across all concurrent requests)

For a higher concurrency, the cache is completly filled, and have to
reboot the machine.
(I didn't leave the system caching forever, just press to reboot
button)... could be interesting to wait to see if the systems recovers
after a while

>>To me, it would not be a problem if the box is very slow under heavy
>>load (DoS like), but I really dislike having my box out of service after
>>such a DoS attack.
>>
>>
>
>Does it not come back?  That's bad.
>
>
see above

thanks
Alex


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