private void stopFlushHandlerThreads(FlushHandler[] flushHandlers, int start, int end) {
    for (int i = start; i < end; i++) {
      flushHandlers[i].shutdown();
      if (LOG.isDebugEnabled()) {
        LOG.debug("send shutdown signal to {}", flushHandlers[i].getName());
      }
    }
  }
@param when When to expire, when to come up out of the queue. Specify in milliseconds. This
            method adds EnvironmentEdgeManager.currentTime() to whatever you pass.
@return This.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java