code: @Deprecated
      public int createThreads(int numberOfThreads) {
  
          int ncreated = 0;
  
          for (int i = 0; i < numberOfThreads; ++i) {
              synchronized (this) {
                  if (poolSize_ < maximumPoolSize_) {
                      addThread(null);
                      ++ncreated;
                  } else
                      break;
              }
          }
  
          return ncreated;
      }
docs: Create and start up to numberOfThreads threads in the pool.
  Return the number created. This may be less than the number
  requested if creating more would exceed maximum pool size bound.
  
  @deprecated This method will go away in a future release. All
  thread creation should be done lazily.