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1578Re: A weird puzzle

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  • Josh Chamas
    Feb 2, 2004
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      Philip Mak wrote:
      > About 10 hours ago, my website started getting really slow. My MRTG
      > graph shows the server's bandwidth usage dropping to 1/4 of its
      > previous amount:
      >
      > http://lina.aaanime.net/~pmak/dropoff.png
      >
      > When I got on the server, the load average was above 7. The shell
      > prompt response time was very slow, the webpages took forever to load,
      > but the CPU was over 90% idle, the swap used was less than the
      > physical memory free, and the si/so/bi/bo values in "vmstat 1" were
      > mostly 0.
      >
      > I couldn't figure out why it was lagging so badly. Then on a whim, I
      > tried "rm -rf" on the StateDir. An empty StateDir was re-created by
      > Apache::ASP, and then the lag problems mysteriously evaporated.
      >
      > Any ideas on how I can prevent this problem from reoccurring? (Damn, I
      > should have saved the StateDir for further analysis instead of
      > deleting it.)
      >

      I have never seen this before. My advice would be to write a program
      to monitor your system load & send you an alert when its over a certain value.
      I would use the 5 minute load value & not 1 minute as 1 minute can be
      fairly volatile.

      Yes, next time, please save the StateDir for possibly reproducing this.
      It may have been something like your site getting slammed by a bot/spider,
      and then the StateDir having to cleanup all the garbage sessions &/or
      deal with really huge internal databases tracking timeouts & such.
      Maybe it was some quirk to do with SDBM_File used for the internal
      database that is used with the session manager. I am not sure we will
      ever know now.

      Regards,

      Josh
      ________________________________________________________________
      Josh Chamas, Founder phone:925-552-0128
      Chamas Enterprises Inc. http://www.chamas.com
      NodeWorks Link Checker http://www.nodeworks.com


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