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Re: Thread question

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On 11/30/2011 4:31 AM, Roedy Green wrote:
> The application is I have a list of 1200 books and a list of 21 online
> bookstores.  I want to find out which bookstores carry the book.  I
> have code now that given a book and bookstore will find out if it
> carries it and records the result.  It probes the appropriate page and
> scans for clues, positive and negative.
>
> The process is very slow because it mostly spends its time waiting for
> the bookstore to respond.  I figured I could fairly easily make one
> book-x-store probe into a Runnable. Happily there is only very simple
> interactions between Runnables.
>
> You could imagine setting all the Runnables loose at once.
>
> I need two features:
>
> 1. some sort of throttle on releasing them that I don't swamp the JVM.

     Use a java.util.concurrent.ExecutorService.  There's a large
number of ways to configure them, but I'd suggest starting out
simple, with a fixed-size thread pool plucking tasks from a queue.

> 2. some  way of knowing when the last one completed.

     A simple counter will do it.  Note that you'll likely want to
be able to proceed without waiting for every last probe to complete:
If you've got twenty answers but qcvfl.com[*] appears hung, it may be
best to abandon the lallygagger and proceed with what you've got.  So,
consider having a time-out as an alternative "completion" signal.

     [*]"Quaint and Curious Volumes of Forgotten Lore."

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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Thread

Thread question Roedy Green <see_website@mindprod.com.invalid> - 2011-11-30 01:31 -0800
  Re: Thread question Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-11-30 01:48 -0800
  Re: Thread question Roedy Green <see_website@mindprod.com.invalid> - 2011-11-30 02:32 -0800
    Re: Thread question Roedy Green <see_website@mindprod.com.invalid> - 2011-11-30 02:48 -0800
    Re: Thread question Patricia Shanahan <pats@acm.org> - 2011-11-30 03:11 -0800
      Re: Thread question Paul Cager <paul.cager@googlemail.com> - 2011-11-30 07:10 -0800
        Re: Thread question Patricia Shanahan <pats@acm.org> - 2011-11-30 09:34 -0800
    Re: Thread question Roedy Green <see_website@mindprod.com.invalid> - 2011-11-30 06:10 -0800
      Re: Thread question markspace <-@.> - 2011-11-30 06:13 -0800
      Re: Thread question Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-11-30 11:53 -0800
  Re: Thread question Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-30 07:28 -0500
    Re: Thread question markspace <-@.> - 2011-11-30 05:30 -0800
      Re: Thread question Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-30 21:04 -0500
        Re: Thread question markspace <-@.> - 2011-11-30 18:28 -0800
  Re: Thread question markspace <-@.> - 2011-11-30 05:50 -0800
    Re: Thread question markspace <-@.> - 2011-11-30 06:04 -0800
  Re: Thread question Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-11-30 11:48 -0800
  Re: Thread question Roedy Green <see_website@mindprod.com.invalid> - 2011-11-30 13:23 -0800

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