How to share the data across threads so that the value get updated properly.

Mark the shared variables as shared. See threads::shared.

Without any testing, something like:

use strict;
 use warnings;
 use threads;
use threads::shared;

 my $currentWrite :shared = 10;
 my $totalSize = 1000;
 sub Progress {
     my $size = shift;
     $currentWrite += $size;
     my $currentProgress = $currentWrite / 100;
     print "Done ", $currentProgress, " of ", $totalSize, "\n";
 }

 sub test {
     my $countRef = shift;
     my $count = $$countRef;
     Progress ( 11);
     print "Current count is $count\n";
 }

 Progress(10);
 my $numThreads = 5;
 my @arrThreads;
 for my $i ( 1 .. $numThreads) {
     my $t = threads->create( \&test, \$i);
     push( @arrThreads, $t);
 }
 foreach (@arrThreads) {
     my $num = $_->join;
 }
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