code: public void prepare(Collection<String> surts) {
          List<String> safeSurts = new ArrayList<String>(surts);
          FetchThread threads[] = new FetchThread[PREPARE_THREAD_COUNT ];
          for (int i = 0; i < PREPARE_THREAD_COUNT ; i++) {
              threads[i] = new FetchThread(safeSurts);
              threads[i].start();
          }
          for (int i = 0; i < PREPARE_THREAD_COUNT ; i++) {
              try {
                  threads[i].join();
              } catch (InterruptedException e) {
              }
          }
      }
docs: Prepare the cache to lookup info for a given set of surts. The fetches
  happen in parallel so this also makes a good option for speeding up bulk lookups.
  
  @param surts