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•Re: Re: •Re: Run N similar tasks in parallel

by merlyn (Sage)
on Feb 20, 2003 at 14:58 UTC ( #237098=note: print w/replies, xml ) Need Help??


in reply to Re: •Re: Run N similar tasks in parallel
in thread Run N similar tasks in parallel

By checking the possible failure of fork, I never "think" I'm working on five kids when only two have really started.

By checking the value of waitpid for a possible -1 return, I never "think" I have kids left when I really don't. The -1 force-resets the hash.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

  • Comment on •Re: Re: •Re: Run N similar tasks in parallel

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Don't wait: waitpid. Why?
by bronto (Priest) on Feb 26, 2003 at 13:00 UTC
    By checking the value of waitpid for a possible -1 return, I never "think" I have kids left when I really don't. The -1 force-resets the hash.

    Good, I should check for the return value of wait as well. Thanks.

    Sorry if I am bothering you about this, but I am missing an information: why do you prefer waitpid to wait? Flexybility? Possibility to make waitpid a non-blocking call? What?

    Thanks in advance.

    --bronto


    The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway).
    --John M. Dlugosz
      Possibility to make waitpid a non-blocking call?
      Ahh, yes. That's it. Although my little snippet of code would never need to wait for more than one process (it'll just loop the outer loop if the waited process is not one of our kids), there are times when I would change just that part of the loop to a "wait until there are no more kids" before moving on.

      So, I'm a bit more familiar with waitpid now, and it makes it easy to step sideways to the multi-wait loop.

      -- Randal L. Schwartz, Perl hacker
      Be sure to read my standard disclaimer if this is a reply.

        Eh, if you wanted to wait until there are no more kids, you want a blocking call, inside a loop, wouldn't you?

        I usually do 1 until -1 == wait;, but waitpid would work just as well.

        Abigail

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