#!/bin/bash

threads=16
counter=0
touch ch
while IFS= read -r line;
do
  if [ "$counter" -lt "$threads" ]; then
    { tar -czvf "${line}.tar.gz" "$line"; echo 'done' > ch; } &
    let $[counter++];
  else
    read -r x < ch # waiting for a process to finish
    { tar -czvf "${line}.tar.gz" "$line"; echo 'done' > ch; } &
  fi
done < <(find offline/*/* -type d)

wait # wait for remaining background processes

rm -f ch

echo 'finished compressing files'