Connection is used in ConnectionConcierge object. There will be failure somewhere else if Connection get GC'ed.

yes, you are right. it needs to be addressed though. I think the close should then happen in the catch instead of automatically.

Or you can put it in finally based on concierge is created or not.

ok :
Connection conn = null;
try {
conn = TransactionLegacy.getStandaloneConnectionWithException();
conn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
conn.setAutoCommit(true);
_concierge = new ConnectionConcierge("LockMaster", conn, true);
} catch (SQLException e) {
s_logger.error("Unable to get a new db connection", e);
throw new CloudRuntimeException("Unable to initialize a connection to the database for locking purposes", e);
} finally {
if (_concierge == null && conn != null) {
try {
conn.close();
} catch (SQLException e) {
s_logger.debug("closing connection failed after everything else.", e);
}
}

having said that, doesn't it make sense to make the goncierge cloasble as well?

Not needed based on its usage in code. The finalize() method is anyway there.