private static void assertNoLocks(final TableName tableName)
    throws IOException, InterruptedException {
    HRegion region = (HRegion) find(tableName);
    assertEquals(0, region.getLockedRows().size());
  }
A test case for issue HBASE-17482 After combile seqid with mvcc readpoint, seqid/mvcc is
acquired and stamped onto cells in the append thread, a countdown latch is used to ensure that
happened before cells can be put into memstore. But the MVCCPreAssign patch(HBASE-16698) make
the seqid/mvcc acquirement in handler thread and stamping in append thread No countdown latch
to assure cells in memstore are stamped with seqid/mvcc. If cells without mvcc(A.K.A mvcc=0)
are put into memstore, then a scanner with a smaller readpoint can see these data, which
disobey the multi version concurrency control rules. This test case is to reproduce this
scenario.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide3.java