I think the way you are joining will work, but it will wait in sequential order, for each thread to join. That is it will wait to join $thr_{0} then on to $thr_{1}, etc. It dosn't take into account which thread finishes first. In the case where you are waiting for ALL threads to finish, it dosn't matter.

But there are cases where you want to detect which thread finishes first, then stop the others when that happens. You could also use a while loop to join each thread as they finish, if you were interested in the finish order, like:

#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;
$| = 1;

my %threads;

foreach (1..10){
  share $threads{$_}{'die'};
  share $threads{$_}{'data'};
  $threads{$_}{'die'} = 0; 
  $threads{$_}{'data'} = 0; 
}

foreach (1..10) {
    $threads{$_}{'thread'} = threads->new('StartTest');
}

my @threads = (1..10);

while(1){
  foreach my $t (@threads){
        if($threads{$t}{'data'} > 5){
             $threads{$t}{'die'} = 1;
             $threads{$t}{'thread'}->join;
             @threads =  grep { $_ != $t } @threads;
    }
     }
if(scalar @threads == 0){last}
}

print "\n", "All threads done\n";
##########################################################

sub StartTest {
    my $self = threads->self;
    print "Thread ", $self->tid, " started\n";
    
    while(1){
    if( $threads{$_}{'die'} == 1){goto FINISH}
       else{ 
           print "From thread $self->",$threads{$_}{'data'}++,"\n";  
       sleep 1;
    };
    }
FINISH:    
    print "Thread ", $self->tid, " ending\n";
}
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