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Re: Nasty MultiThread problem

by zentara (Archbishop)
on Nov 19, 2005 at 12:51 UTC ( [id://510081]=note: print w/replies, xml ) Need Help??


in reply to Nasty MultiThread problem

Hi, your code is kind of long, and the wrong OS, for me to test; but I think you may be running into the common misconception that $thread->join forces a thread to terminate. It dosn't as the following code shows:
#!/usr/bin/perl use warnings; use strict; use threads; # join() does three things: it waits for a thread to exit, # cleans up after it, and returns any data the thread may # have produced. my $thr = threads->new(\&sub1); my $return = $thr->join; print "Thread returned @$return\n"; #hold for key input <>; ########################################################## sub sub1 { my @values = ('1',2, 'ten'); print "@values\n"; while(1){sleep 1} return \@values; }

If you can't be sure that all your threads have reached the end of their code block, before you try to join them, you can force them to die with a shared variable. See how this minor modification will force the thread to return early, and thus be joinable.

#!/usr/bin/perl use warnings; use strict; use threads; use threads::shared; # join() does three things: it waits for a thread to exit, # cleans up after it, and returns any data the thread may # have produced. my $die : shared = 0; my $thr = threads->new(\&sub1); #hold for key input <>; $die=1; my $return = $thr->join; print "Thread returned @$return\n"; #hold for key input <>; ########################################################## sub sub1 { my @values = ('1',2, 'ten'); print "@values\n"; while(1){ sleep 1; if($die){return \@values } } return \@values; }

I'm not really a human, but I play one on earth. flash japh

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