I would build a tree of parent ids:

use strict;
use warnings;
use Proc::ProcessTable;

my $p = new Proc::ProcessTable;
my $t = $p->table;
my %tree;
$tree{$_->pid} = $_->ppid for @$t;

for my $process ( @$t ) {
  print $process->cmndline;
  my $pid = $process->pid;
  while( $pid > 1 ) {
    print "->$pid";
    $pid = $tree{$pid}
  }
  print "->$pid\n";
}
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