public void shutdown() {
      if (!running) {
        return;
      }
      shutdownRequested = true;
      interrupt();
      try {
        join();
      } catch (InterruptedException ignore) {
        Thread.currentThread().interrupt();
        // just return, we're done
      }
    }
Stops this thread. Does not return until it has stopped.
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/IndexManager.java