I'm in no position to argue against BrowserUk's expertise concerning threads, but sometimes us "amateur" programmers get stuck on using simple methods when faced with complex problems. In your case, BrowserUk showed you the problem of the threads needing to "finish their code block" before they can join.

What I have taken to doing is putting a FINISH: label at the end of the thread-code-block, and when I want to join a thread, I send it a die signal thru a shared variable. In the thread-code, test for the shared-var in your loop, and if "condition is met", put a "goto FINISH" in the statement. Then whenever you want to join the thread, you do 2 things, send the die, then join. I like using hashes to keep track of it all. Also, if you "detach" you can't join.

#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;

$| = 1;

my %threads;

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

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


my @threads = (1..10);
foreach(@threads){
    $threads{$_}{'die'} = 1;
    $threads{$_}{'thread'}->join;
}

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{ select(undef,undef,undef, 10) };
    }
FINISH:
    print "Thread ", $self->tid, " ending\n";
}
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