class Sln {

    AtomicInteger globalCounter = new AtomicInterger();
    Map<String, Integer> counterPerKey = new ConcurrentHashMap<>()

class Holder{
    Integer value
}

    public Holder doWorkMultipleThreads(String key) {
         if (total.get() < 1000) {

          Integer newTotal = counterPerKey.merge(key, 1, Integer::sum);
          globalCounter.increment();
         return new Holder(newTotal);

    }

}

}