private Collection<LockComponent> getGlobalLocks(Configuration conf) {
    String lockNames = conf.get(Constants.HIVE_QUERY_EXCLUSIVE_LOCK);
    if (StringUtils.isEmpty(lockNames)) {
      return Collections.emptyList();
    }
    List<LockComponent> globalLocks = new ArrayList<LockComponent>();
    for (String lockName : lockNames.split(",")) {
      lockName = lockName.trim();
      if (StringUtils.isEmpty(lockName)) {
        continue;
      }
      LockComponentBuilder compBuilder = new LockComponentBuilder();
      compBuilder.setExclusive();
      compBuilder.setOperationType(DataOperationType.NO_TXN);
      compBuilder.setDbName(GLOBAL_LOCKS);
      compBuilder.setTableName(lockName);

      globalLocks.add(compBuilder.build());
      LOG.debug("Adding global lock: " + lockName);
    }
    return globalLocks;
  }
This is here for documentation purposes.  This TM doesn't support this - only has one
mode of operation documented at {@link DbTxnManager#isExplicitTransaction}
ql/src/java/org/apache/hadoop/hive/ql/lockmgr/DbTxnManager.java