my $thread1 = $thread->create(sub { print "I am a thread1"},$variable1);

my $thread2 = $thread->create(sub { print "I am a thread2"},$variable2);

if($pid == 0){
  &abfrage($die_ersten_~100_zeilen); #  child prozess muesste das sein, oder?
}
else{
  &abfrage($die_naechsten_~100_zeilen); # parentprozess muesste das sein, oder?
}

use Thread;

#...

sub verarbeite_10_zeilen_in_thread($)
{ return Thread->new(\&verarbeite_10_zeilen,$_[0]); }

sub verarbeite_10_zeilen($)
{
  my @zeilen=@$_[0];
  # mach hier was du willst
  return("irgendwas", 42);
}

my @threads;

my @ten_lines;
my $cnt=0;
open(DAT,'<',$datei) or die $!;
while(my $line=<DAT>)
{
  push(@ten_lines,$line);
  $cnt++;
  if($cnt>=10)
  {
   $cnt=0;
   push(@threads,&verarbeite_10_zeilen_in_thread([@ten_lines]));
   @ten_lines=();
  }
}
# übrig geblibenen Zeilen verarbeiten
push(@threads,&verarbeite_10_zeilen_in_thread([@ten_lines])); if(@ten_lines>0);
close(DAT);

my @back;
push(@back,[$thread->join()]) for my $thread (@threads);
mach irgendwas mit den zurückgebenen Werten in @back ...

#! /usr/bin/env perl

use strict;
use warnings;
use Getopt::Long;
use POSIX ":sys_wait_h";

GetOptions('-i=s' => \my $infile);
       
my ($counter,$index,@lines) = (1,0);

open my $fh,"<",$infile or die "Can't open $infile: $!";
while(my $line = <$fh>){
  push @{$lines[$index]},$line;
  $index++ if $counter++ % 10 == 0;
}

fork_it(\@lines);


#------------------------------------------#
# Subroutines                              #
#------------------------------------------#



sub do_something_with_lines{
  my ($lines,$nr) = @_;
  print $nr,": ",$_ for @$lines;
}


sub fork_it{
  my ($linesref) = @_;
  
  my %pids;
  
  for (1..scalar(@$linesref)){
    my $pid=fork();
    if($pid==-1){
      warn($!);
      last;
    }
    if($pid){
      $pids{$pid}=1;
    }
    else{
      do_something_with_lines($linesref->[$_-1],$_-1);
      exit(0);
    }
  }
  while(keys %pids){
    my $pid=waitpid( -1, WNOHANG );
    die "$!" if $pid == -1;
    delete $pids{$pid};
  }
}