@Test
  public void testSynchronized() throws Exception {
    int currentNumberOfDbs = client.getAllDatabases().size();

    IMetaStoreClient synchronizedClient =
      HiveMetaStoreClient.newSynchronizedClient(client);
    List<String> databases = synchronizedClient.getAllDatabases();
    assertEquals(currentNumberOfDbs, databases.size());
  }
Tests {@link HiveMetaStoreClient#newSynchronizedClient}.  Does not
actually test multithreading, but does verify that the proxy
at least works correctly.
standalone-metastore/metastore-server/src/test/java/org/apache/hadoop/hive/metastore/TestHiveMetaStore.java