for (...) {
   ...
   push(@forkArray, $level);
   push(@forkArray, $writeCounter);
   push(@forkArray, $nextMerge);
}

for (my $ct = 0; $ct <= $#forkArray; $ct+=3) {
   my $level      = $forkArray[$ct+0];
   my $mergeLast  = $forkArray[$ct+1];
   my $mergeFirst = $forkArray[$ct+2];
   ...
}