perl multithreading perl exited with active threads - multithreading

Question

I write perl script to do a certain but I needed to mutlithread it, but I get this:
Perl exited with active threads:
2 running and unjoined
0 finished and unjoined
0 running and detached
Here is the code:
use Net::Ping;
use threads;
use Benchmark qw(:hireswallclock);
use threads::shared;
my $starttime = Benchmark->new;
my $finishtime;
my $timespent;
my $num_of_threads = 2;
my #threads = initThreads();
my $inFile = $ARGV[0] ;
open(IN , "<$inFile") or die "can not find $inFile" ;
my #output: shared = <IN>;
chomp (#output) ;
my $chunk_size = #output / 2;
print($chunk_size);
#############################
######## PROCEDURES ########
#############################
# Subroutine that intializes an array that will contain all our threads:
sub initThreads{
my #initThreads; # Our array
for(my $i=1; $i<=$num_of_threads; $i++){
push(#initThreads, $i);
}
return #initThreads;
}
sub doScript{
my $id = threads->tid();
print "//////////////////////////////////////////////////////////////////////////////////////////////Starting thread $id\n";
my ($start, $end, $output) = #_;
for my $i ($start .. $end) {
## some stuff done
sleep 1 if 0.2 > rand;
}
print "/////////////////////////////////////////////////////////////////////////////////////////////////////////////////Thread $id done!\n";
threads->exit();
}
########################
######## MAIN ########----------------------------------------------------------------
########################
for my $chunk(1 .. 2){
my $start = ($chunk - 1) * $chunk_size;
push #threads, threads->create(
\&doScript,
$start,
($start + $chunk_size - 1),
\#output,
);
print("finish");
}
# This tells the main program to keep running until all threads have finished.
foreach(#threads){
threads->join();
}
$finishtime = Benchmark->new;
$timespent = timediff($finishtime,$starttime);
print "\nDone!\nSpent ". timestr($timespent);
#print "\nProgram Done!\nPress Enter to exit\n";
$a = <>;
close (IN);
I even replaced the join block with this:
$_->join() for threads->list();
the error was solved but the script seemed not to do anything, threads started and terminated without doing anything.
Can anyone help me with this !

Answer 1

The reason you get that error is exactly as said on the tin - your code exited before the threads were closed. It can commonly happen when an exit or die is triggered early.
In particular I think your problem may lie within your reusing of #threads and initThreads().
The latter returns a list of numbers, not any threads. And then you push a couple more threads to the end of the list later, when you're doing a create.
That looks a lot like some sort of logic error to me.
But the major problem I think will be this:
foreach(#threads){
threads->join();
}
You're not actually joining a specific thread. What you probably want is:
foreach my $thr ( #threads ) {
$thr -> join();
}
At least, you would, if you hadn't manually populated #threads with [1,2] thanks to my #threads = initThreads();