Beginner: Threads and Variables

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I'm experimenting with Perl and Threads at the moment and wondering if it is possible to do the following. I have the following code, what I want to know is how to make it so that when sub1 changes the $status to 0's, how can I make sub2 also register the variable's value change. Is this possible with threads? Is there another method I could use that would allow two while-loops running, while being able to change each others variable values?

use strict;
use Thread;

my $thr1;
my $thr2;
my $status = "1111";
   
      
print "Started\n";

$thr1 = new Thread \&sub1;
$thr2 = new Thread \&sub2;


sub sub2 {
    while (1)     {
            print $status;
            }
    }


sub sub1 { 

      while (1)    {   
              $status = "0000";
              print $status;
            } 
    }
    

$thr1->join;
$thr2->join;
[download]

Comment on Beginner: Threads and Variables Download Code

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Re: Beginner: Threads and Variables by IlyaM (Parson) on Nov 14, 2002 at 10:10 UTC
I haven't used threads in Perl yet so I can be wrong but I think you have to declare variable as shared: `use threads::shared; my $status : shared;` [download] See 'perldoc threads::shared' for details. -- Ilya Martynov, ilya@iponweb.net CTO IPonWEB (UK) Ltd Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net Personal website - http://martynov.org	[reply] [d/l]
Re: Beginner: Threads and Variables by broquaint (Abbot) on Nov 14, 2002 at 12:16 UTC
Something like this perhaps `use strict; use threads; use threads::shared; print "Started\n"; my $status : shared = 0; my $thr1 = threads->new( sub { sleep(1) and print "thread1: $status\n" while 1; } ); my $thr2 = threads->new( sub { sleep(1) and print "thread2: status incremented\n" while ++$status; } ); $thr1->join; $thr2->join; __output__ Started thread1: 1 thread2: status incremented thread1: 2 thread2: status incremented thread1: 3 thread2: status incremented thread1: 4 ...` [download] This requires perl5.8.0 compiled with threading, or with a slight modification, perl5+ without threading and using the inspired `forks` module. HTH `_________ broquaint` update: fixed `forks` link per RMGir's node	[reply] [d/l]
Re: Re: Beginner: Threads and Variables by RMGir (Prior) on Nov 14, 2002 at 14:20 UTC
the inspired forks module Unfortunately, search.cpan.org has issues. Your link takes me to Net::Server::PreForkSimple rather than Elizabeth Mattijsen's forks module. You're right, though, that's one cool module. -- Mike	[reply]