code: private void adjustPoolSize() {
          if (lastCheck + 1000 < System.currentTimeMillis()) {
              int n = Runtime.getRuntime().availableProcessors();
              if (numProcessors != n) {
                  executor.setMaximumPoolSize(n);
                  numProcessors = n;
              }
              lastCheck = System.currentTimeMillis();
          }
      }
docs: Adjusts the pool size at most once every second.