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Re: Useful number of childs revisited

by KurtSchwind (Chaplain)
on May 08, 2015 at 14:14 UTC ( [id://1126100]=note: print w/replies, xml ) Need Help??


in reply to Useful number of childs revisited [SOLVED]

Several years ago I was writing ETL for a very large datawarehouse (think top 10 databases in the world, although this was over a decade ago). And I did this on Sun's E10k frames which were multiple CPU (this pre-dates multi-core).

Because there are different ways of being 'bound', Memory-Bound, CPU-Bound, Network-Bound, Disk I/O-Bound, etc... the only way to truly know the optimal number of threads is by trial and error. At least with a program of any complexity. So you run tests and trials and you plot it out and it should be pretty clear where the sweet spot is.

--
“For the Present is the point at which time touches eternity.” - CS Lewis

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Re^2: Useful number of childs revisited
by karlgoethebier (Abbot) on May 08, 2015 at 17:43 UTC
    "...run tests and trials... should be pretty clear where the sweet spot is"

    Yes - what else should i do?

    But i think that you agree that the phenomenon i described is - to put it mildly (gelinde gesagt?) - surprising unexpected.

    Edit: Minor change of wording - i said this already.

    Thanks and best regards, Karl

    «The Crux of the Biscuit is the Apostrophe»

      BTW: The simple cure for the problem would be to switch sleep for select( '','','', $timeout ), which would allow the timeout to be specified in fractional seconds; and set the default to something like 0.01. (Without adding a dependency upon Time::HiRes )


      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority". I'm with torvalds on this
      In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked
        "...to switch sleep for select( '','','', $timeout )..."

        Unfortunately i must admit that i don't understand this.

        Best regards, Karl

        «The Crux of the Biscuit is the Apostrophe»

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