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Re^8: Threaded Code Not Faster Than Non-Threaded -- Why?

by Tommy (Chaplain)
on Jan 06, 2014 at 04:55 UTC ( #1069452=note: print w/ replies, xml ) Need Help??


in reply to Re^7: Threaded Code Not Faster Than Non-Threaded -- Why?
in thread Threaded Code Not Faster Than Non-Threaded -- Why?

It isn't nearly finished and is undergoing a transformation since I typed my response, but at the time of this writing you can find the threading code here

One of the first things you'll notice is that I didn't implement a "guard" or "doorman". I'm just stuffing everything in the queue for now. Even on directory trees larger than 200GB it barely takes more than 200MB RAM.

Tommy
A mistake can be valuable or costly, depending on how faithfully you pursue correction


Comment on Re^8: Threaded Code Not Faster Than Non-Threaded -- Why?
Re^9: Threaded Code Not Faster Than Non-Threaded -- Why?
by BrowserUk (Pope) on Jan 06, 2014 at 07:06 UTC

    I'd suggest trying the following modification:

    my $thread_term :shared = 0; my $threads_init :shared = 0; my $file_read_sem : shared; + ### Add this ... WORKER: while ( !$thread_term && defined ( my $file = $work_queue-> +dequeue ) ) { { + ### Add this lock $file_read_sem; + ### Add this open my $fh, '<', $file or do { lock $d_counter; $d_counter++ +; next WORKER }; my $data = <$fh>; close $fh; } + ### Add this

    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".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      I'd suggest trying the following modification

      ...To prevent disk thrashing?

      Tommy
      A mistake can be valuable or costly, depending on how faithfully you pursue correction
        To prevent disk thrashing?

        Yes. But you'll need to try it; and the effects will probably vary for different file systems.

        For lots of small files it might speed things up; for lots of big ones it might slow things down. For a mix; you'll need to measure.


        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".
        In the absence of evidence, opinion is indistinguishable from prejudice.

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