@Override
  public void run() {
    if (this.server.isStopping() || this.server.isStopped()) {
      LOG.debug("Skipping split because server is stopping=" + this.server.isStopping()
        + " or stopped=" + this.server.isStopped());
      return;
    }

    doSplitting();
  }
Handles processing region splits. Put in a queue, owned by HRegionServer.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/SplitRequest.java