public static void blockUntilRegionIsInMeta(Connection conn, long timeout, RegionInfo hri)
    throws IOException, InterruptedException {
    log("blocking until region is in META: " + hri.getRegionNameAsString());
    long start = EnvironmentEdgeManager.currentTime();
    while (EnvironmentEdgeManager.currentTime() - start < timeout) {
      HRegionLocation loc = MetaTableAccessor.getRegionLocation(conn, hri);
      if (loc != null && !loc.getRegion().isOffline()) {
        log("found region in META: " + hri.getRegionNameAsString());
        break;
      }
      Threads.sleep(100);
    }
  }
Blocks until the region split is complete in hbase:meta and region server opens the daughters
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestEndToEndSplitTransaction.java