@Test
  public void testFlushPrimary() throws Exception {
    openRegion(hriSecondary);

    try {
      flushRegion(hriPrimary);

      Put p = new Put(row);
      p.addColumn(f, row, row);
      table.put(p);

      flushRegion(hriPrimary);
    } finally {
      Delete d = new Delete(row);
      table.delete(d);
      closeRegion(hriSecondary);
    }
  }
This copro is used to synchronize the tests.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestReplicasClient.java