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Re^2: Perl thread/semaphore

by password (Sexton)
on May 03, 2011 at 22:47 UTC ( #902777=note: print w/replies, xml ) Need Help??


in reply to Re: Perl thread/semaphore
in thread Perl thread/semaphore

Dear oshalla, thank you for your codes, it really helped me to grasp several ideas about threading in Perl. My only addition would be that's in your 1st and 2nd examples you clone the arguments (@array) in the first two cycles, meaning you're creating two threads with the same arguments: for (1..2) - in the 1st example and while ($c) - where $c=2 - in the 2nd example To fix that I used a new variable to count dispatched threads.
#!/usr/bin/perl use strict ; use warnings ; use threads ; use Thread::Queue ; my @array = qw(a b c d e f g h); my @results; my $finished_queue = new Thread::Queue ; my $c = 5 ; # Number active at once my $n = 10 ; # Total number to dispatch my $m = $n ; # Number to collect my $d = 0; #count created threads while ($n) { while ($m) { $d++; my $child = threads->create(\&sub_thread, @array) ; my $tid;my $childa; if ($d == $c) { $tid = $finished_queue->dequeue() ; $childa = threads->object($tid) ; push @results, $childa->join() ; $d--; $n--; } $m-- ; } if (!$m) { my $tid = $finished_queue->dequeue() ; my $childa = threads->object($tid) ; push @results, $childa->join() ; $n--; } } sub sub_thread { my (@temp) = (@_) ; my $tid = threads->tid() ; print "child $tid: @temp\n" ; sleep(rand(2)+2) ; $finished_queue->enqueue($tid) ; print "child $tid: finished\n" ; return "whatever from child $tid" ; } ; exit;
It's not elegant, but it works and all I needed was a quick fix. P.S. It's an old thread, but it was the most useful for me just now, so I'd rather share the solution in this old thread.

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