@Override
    protected boolean setInMemoryCompactionFlag() {
      boolean rval = super.setInMemoryCompactionFlag();
      if (rval) {
        RUNNER_COUNT.incrementAndGet();
        if (LOG.isDebugEnabled()) {
          LOG.debug("runner count: " + RUNNER_COUNT.get());
        }
      }
      return rval;
    }
This test is for HBASE-26494, test the {@link RefCnt} behaviors in {@link ImmutableMemStoreLAB}
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHStore.java