#!/usr/bin/perl
use threads;
use IO::Uncompress::Gunzip;
use IO::Compress::Gzip;

my $testfile = 'test.gz';

# create compressed file
my $fh = new IO::Compress::Gzip($testfile);
print {$fh} "$_ qwertyuiopasdfghjklzxcvbnm\n" foreach(1..5000);
close($fh);

print "$testfile created\n";

# read compressed file, starting a thread for every 500 lines
$fh = new IO::Uncompress::Gunzip($testfile);
my @chunk = ();
while(my $line = <$fh>) {
        push(@chunk,$line);
        if(scalar(@chunk) == 500) {
                my $th = threads->create(\&test,\@chunk);
                @chunk = ();
                $th->join();
        }
}
my $th = threads->create(\&test,\@chunk);
$th->join();
close($fh);

sub test {
        my ($lines) = @_;
        print foreach(@$lines);
}