I'm trying to split a large file into smaller chunks, and then use threads to upload the chunks to an FTP server. This is to speed up the transfer with multiple connections uploading a piece of the file. Here's what I've tried so far but its not working when using threads, the program seems to hang or block, and the file on the FTP server is 0 size. Any help would be appreciated.

#!/usr/bin/perl -w
use strict;
use warnings;
use Net::FTP;
use Config;
$Config{useithreads} or die('Recompile Perl with threads to run this p
+rogram.');
use threads;

my $file = 'c:\sdwork\dla495.txt';

my $ftp = Net::FTP->new("ftpserver") or die "can't get ftp object\n";
$ftp->login("fakeusr", "secret") or die "can't login to ftp server\n";
$ftp->binary();
$ftp->cwd('/home/fakeusr/tmp');

open (FH, "<$file") or die "Could not open source file. $!";
binmode(FH);

my $i = 0;

my $start_byte = 0;
my @THRD_LIST;
my $thrd;

while (1) {
   my $chunk;
   print "process part $i\n";
   
   $i ++;
   if (!eof(FH)) {
      my $bytes_read = read(FH, $chunk, 10000);  #bytes
      print "bytes read: $bytes_read\n";
      
      #test with threads
      $thrd = threads->create (\&transfer_chunks, $start_byte, $chunk)
+ or die "Failed to start the thread: $@\n";
      push (@THRD_LIST, $thrd);
      
      #test without threads
      #transfer_chunks($start_byte, $chunk);
      
      $start_byte += $bytes_read + 1;
      print "start byte: $start_byte\n";
   } 

   last if eof(FH);
}

# start the threads
for $thrd (@THRD_LIST) {
  $thrd->join();
}

$ftp->quit;

sub transfer_chunks {
   my ($start_byte, $chunk) = @_;
   # convert perl string into a filehandle
   open(TEST, '<', \$chunk);
   
   $ftp->restart($start_byte);
   $ftp->put(*TEST, 'testfile.txt');
   ##$ftp->append(*TEST, 'testfile.txt');
   close(TEST);
}
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