Develop Reference

Multi-tenant hibernate doesn't switch between tenants

I am in the middle of changing my spring + hibernate + mysql setup to be multi-tenant. First of all, I have the following in my application.properties:
spring.datasource.url=jdbc:mysql://localhost:3306/test?useSSL=false
spring.datasource.username=root
spring.datasource.password=root
I am not sure if I'm supposed to make it connect to a specific schema here (test) after introducing multi-tenancy? It doesn't make sense to me, as it's supposed to use a default schema if no tenant is provided, otherwise connect to the schema associated with the tenant. However, if I remove it I get an error that no database was provided.
Secondly, the multi-tenant part doesn't seem to be working. All my queries are made in the test schema. I have implemented the following MultiTenantConnectionProvider:
#Component
public class TenantConnectionProvider implements MultiTenantConnectionProvider {
private Datasource datasource;
public TenantConnectionProvider(DataSource datasource) {
this.datasource = datasource;
}
...
#Override
public Connection getConnection(String tenantIdentifier) throws SQLException {
logger.info("Get connection for tenant {}", tenantIdentifier);
final Connection connection = getAnyConnection();
connection.setSchema(tenantIdentifier);
return connection;
}
#Override
public void releaseConnection(String tenantIdentifier, Connection connection) throws SQLException {
logger.info("Release connection for tenant {}", tenantIdentifier);
connection.setSchema(DEFAULT_TENANT);
releaseAnyConnection(connection);
}
}
I am getting no errors, and when I make a query it correctly prints Get connection for tenant with the correct tenantIdentifier that matches the name of one of my other schemas. Still, it queries the test schema. What am I missing? Thanks!
EDIT:
It seems like connection.setSchema(tenantIdentifier) has no effect. In the method's description, it says the following: If the driver does not support schemas, it will silently ignore this request. So I'm guessing my driver does not support it? What to do in that case?

Using connection.createStatement().execute("USE " + tenantIdentifier); instead of connection.setSchema(tenantIdentifier); solved my problem.

Hibernate session successfully update object, but occasionally not

I working with PostgreSQL in multithread mode by Hibernate sessions. Init:
<property name="connection.driver_class">org.postgresql.Driver</property>
<property name="hibernate.current_session_context_class">thread</property>
(other strings is connection URL and entity xml describe))
HibernateUtil:
public class HibernateUtil {
private static SessionFactory sessionFactory;
static {
try {
Configuration configuration = new Configuration();
configuration.configure();
sessionFactory = configuration.buildSessionFactory();
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
public static Session getSession() {
return sessionFactory.getCurrentSession();
}
public static void close() {
sessionFactory.close();
}
public static void setSessionFactory(SessionFactory factory) {
sessionFactory = factory;
}
}
All CRUD actions with Entities i do in separate class, where every action execute in one transaction.
public class SessionService {
public static <T> T get(Class<T> classvar, int id) {
Session session = HibernateUtil.getSession();
session.beginTransaction();
T result = session.get(classvar, id);
session.getTransaction().commit();
return result;
}
// Some other code
public static void update(Object obj) {
Session session = HibernateUtil.getSession();
session.beginTransaction();
session.update(obj);
session.getTransaction().commit();
}
}
There is no problems with multithreading work (or i not see it). But, some time ago i seen strange bug. I got one record from db by SessionService.get(Entity.class, 1). Change one field of this entity and save it by SessionService.update(entity). Update was successfull done without exceptions (logging approved). But changes not seen in database. In runtime entity has this changes, but not in db. I wait some time (for flush and others) but nothing changed.
Tried to repeat bug - all good, bug not found. In one day i catch this bug on production server with 19 objects from 200, but in other days i not seen this bug.
Last importan moment: i dont catched this bug with other entities (or i dont see them).
What may be reason of it? May be better use entity manager instead sessions?

Can you please post the entire hibernate.cfg.xml file (delete the username and password of course).
Also are you 100% sure that you do not get an error like (wild guess) :
A different object with the same identifier value was already associated with the session ?
There are errors while running Hibernate, that literary flashes in the console for half a second when running queries.
Had this problem a while back.

Is Spring JdbcTemplate thread safe?

I'm using Spring JdbcTemplate on one of my projects and now, when there are really very much requests with it - I started to face this exception:
org.springframework.jdbc.UncategorizedSQLException: CallableStatementCallback;
uncategorized SQLException for SQL [{? = call API.get_data_for_nb(?, ?)}];
SQL state [99999]; error code [17009]; Closed Statement;
nested exception is java.sql.SQLException: Closed Statement
So the Closed Statement exception is received when you try to execute statement that is already closed, but in my case I don't close it by myself - I use JdbcTemplate exactly for that. So, firstly, what could be the reason for that?
The JdbcTemplate object itself is contained in #Stateless EJB in this way:
#Stateless(name = "NbEdwServiceEJB")
public class NbEdwServiceBean implements NbEdwServiceLocal, NbEdwServiceRemote {
#Resource(mappedName = JNDI)
private DataSource dataSource;
private static volatile JdbcTemplate jdbcTemplate;
#PostConstruct
protected void construct() {
synchronized (NbEdwServiceBean.class) {
if (jdbcTemplate == null) {
jdbcTemplate = new JdbcTemplate(dataSource);
jdbcTemplate.setResultsMapCaseInsensitive(true);
}
}
}
private String getDataFromDB(final String request, final int isDigitalSignVerified) {
String response = null;
try {
response = jdbcTemplate.execute(SQL_GET_DATA, new CallableStatementCallback<String>() {
public String doInCallableStatement(CallableStatement cs) throws SQLException, DataAccessException {
cs.registerOutParameter(1, Types.VARCHAR);
cs.setInt(2, isDigitalSignVerified);
cs.setString(3, request);
cs.executeUpdate();
return cs.getString(1);
}
});
} catch (DataAccessException ex) {
LOGGER.error("getDataFromDB()", ex);
}
return response;
}
}
I know that this is maybe not the strictly right way to do it, I could just create instance of JdbcTemplate for every stateless bean - so I might do just that. So, secondly, why is this ever happening? My suppose was that JdbcTemplate's execute method isn't thread safe, but can someone give the full explanation on what is going on?
I have JEE version 5 running on WebLogic 10.3.5 if it's matter.

#Tolegen Izbassar I'm sorry that you're stuck with EE5.
Concerning the Singleton and EE5 there were some alternatives out there. One is vendor specific extensions, for example JBoss 5.x had service beans providing Singleton+JMX. A second solution is to use a earlier version of Jboss Seam compatible with EE5. A third alternative is to use the ServerContext from the Servlet API.
What you're trying to do in #PostConstuct is definitely not good. Non final statics in SLSB is a no go.
I suggest to have a look, at section 29.3 from Spring framework reference which describes EJB - Spring integration, an example from that section:
#Stateless
#Interceptors(SpringBeanAutowiringInterceptor.class)
public class MyFacadeEJB implements MyFacadeLocal {
// automatically injected with a matching Spring bean
#Autowired
private MyComponent myComp;
// for business method, delegate to POJO service impl.
public String myFacadeMethod(...) {
return myComp.myMethod(...);
}

spring bean startup/shutdown order configuration (start h2 db as server)

I'd like to create configuration/bean to automatically start H2DB in my development profile. I'd like to have it running as a tcp server. It's needed to be started before any DataSource configuration. Can someone tell me how to achieve this?
Wha have I done is
#Profile("h2")
#Component
public class H2DbServerConfiguration implements SmartLifecycle {
private static final Logger logger = LoggerFactory.getLogger(H2DbServerConfiguration.class);
private Server server;
#Override
public boolean isAutoStartup() {
return true;
}
#Override
public void stop(Runnable callback) {
stop();
new Thread(callback).start();
}
#Override
public void start() {
logger.debug("############################################");
logger.debug("############################################");
logger.debug("STARTING SERVER");
logger.debug("############################################");
logger.debug("############################################");
try {
server = Server.createTcpServer("-web", "-webAllowOthers", "-webPort", "8082").start();
} catch (SQLException e) {
throw new RuntimeException("Unable to start H2 server", e);
}
}
#Override
public void stop() {
logger.debug("############################################");
logger.debug("############################################");
logger.debug("STOPPING SERVER");
logger.debug("############################################");
logger.debug("############################################");
if (server != null)
if (server.isRunning(true))
server.stop();
}
#Override
public boolean isRunning() {
return server != null ? server.isRunning(true) : false;
}
#Override
public int getPhase() {
return 0;
}
}
but this isn't an option for me because component is created after datasource (I have liquibase setup so it's too late) and Phase is still the same that means FIFO order and I'd like to be FILO.

Mix #Profile and #Component seams to me a bad idea. Profiles are designed to work with Configuration (documentation)
Do you really need profile? In my opinion it makes sense if you have several possible configurations, one based on H2, and if you want be able to switch between these configurations (typically at start time by setting a properties...)
Manage the H2 server with a bean (documentation) seams correct to me (as suggested by Stefen). Maybe you will prefer annotations... If you want a spring profile, then you will need a Configuration object too. It will simply load the H2 server bean (in my opinion it's better to manage the H2 server lifecycle with a bean than with a context/config).

Create your server as a bean :
#Bean(initMethod = "start", destroyMethod = "stop")
Server h2Server() throws Exception {
return Server.createTcpServer("-tcp","-tcpAllowOthers","-tcpPort","9192");
}
Now you can configure spring to create other beans (e.g the datasource)
after the bean h2Server using #DependsOn
#DependsOn("h2Server")
#Bean
DataSource dataSource(){
...
}
Hi, what about using spring boot? It has automatically configured datasource so I don't want to reconfigure it.
You are right, to use the above approach you have to create your own datasource in order to annotate it with #DependsOn .
But it looks like this is not really necessary.
In one of my projects I am creating the h2Server as a bean as described.
I use the datasource created by spring, so without any #DependsOn.
It works perfectly. Just give it a try.
Your solution with SmartLifecycle does not work, because it creates the server on ApplicationContext refresh, which happens after all beans (including the datasource ) were created.

Hibernate and multiThread Logic

Im working on a java standAlone project. I need to use hibernate in a MultiThread application but i just cant figure it out how to set up this correctly.
Each Thread deals with the same process of the others.
Everything goes Ok when i run it in a Non-Async way, but when i call the same thing using threads, hibernate just don't work fine.
Can anyone please explain me what's the correct way to use Hibernate in a multiThread Java Stand-Alone App?
Hibernate Util
public class HibernateUtil {
private static final Session session;
static {
try {
SessionFactory sessionFactory;
Properties properties = new Properties();
properties.load(new FileInputStream("middleware.properties"));
Configuration cfg = new Configuration().configure();
cfg.addProperties(properties);
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()
.applySettings(cfg.getProperties()).build();
sessionFactory = cfg.buildSessionFactory(serviceRegistry);
session = sessionFactory.openSession();
} catch (IOException | HibernateException he) {
JOptionPane.showMessageDialog(null, DataBaseMessage.CONNECTION_ERROR.getMessage(), DataBaseMessage.CONNECTION_ERROR.getTitle(),JOptionPane.ERROR_MESSAGE);
throw new ExceptionInInitializerError(he);
}
}
public static Session getSession() {
return session;
}
The Error comes here
TbHistoDespachos despacho = Dao.findDespachoByTagId(element.getChild("tagID").getText());
public synchronized List<TbHistoDespachos> ExractDespachoAndNotify(String data, String nombreConexion) {
List<TbHistoDespachos> despachos = new ArrayList<>();
String nombreConexionUpp = nombreConexion.toUpperCase();
try {
Document doc = convertStringToDocument(data);
if (!doc.getRootElement().getChild("reply").getChild("readTagIDs")
.getChildren().isEmpty()) {
for (Element element : doc.getRootElement().getChild("reply").
getChild("readTagIDs").getChild("returnValue")
.getChildren()) {
TbHistoDespachos despacho = Dao.findDespachoByTagId(element.getChild("tagID").getText());
if (despacho != null) {
if(evaluateDespacho(nombreConexionUpp, despacho)){
despachos.add(despacho);
}
}
}
}
} catch (JDOMException | IOException ex) {
JOptionPane.showMessageDialog(null, FilesMessageWarnings.NOTIFICATION_SAP_WARNING.
getMessage().replace("&nombreConexion", nombreConexion).replace("&tagID", ""),
FilesMessageWarnings.NOTIFICATION_SAP_WARNING.getTitle(), JOptionPane.WARNING_MESSAGE);
}
return despachos;
}
Here is the DAO
public class Dao {
private static Session sesion;
public static TbHistoDespachos findDespachoByTagId(String tagId) {
TbHistoDespachos despacho = null;
try {
startTransmission();
despacho = (TbHistoDespachos)sesion.createQuery("FROM TbHistoDespachos WHERE TAG_ID =:tagId")
.setParameter("tagId", tagId)
.uniqueResult();
stopTransmission();
} catch (HibernateException he) {
System.out.println("error: " + he.getMessage());
JOptionPane.showMessageDialog(null, DataBaseMessage.QUERY_ERROR.getMessage(),
DataBaseMessage.QUERY_ERROR.getTitle(), JOptionPane.ERROR_MESSAGE);
}
return despacho;
}
private static void startTransmission() {
sesion = HibernateUtil.getSession();
sesion.getTransaction().begin();
}
private static void stopTransmission() {
sesion.getTransaction().commit();
sesion.getSessionFactory().getCurrentSession().close();
sesion.clear();
}
ANY IDEAS?

The problem stems from static Session variables. A SessionFactory is thread-safe and, generally speaking, you only need one (static) instance per database. A Session, on the other hand, is not thread-safe and is usually created (using a SessionFactory) and discarted/closed on the fly.
To solve your immediate problem, remove the static Session sesion variable from your Dao and also 'inline' the startTransmission and stopTransmission methods in the findDespachoByTagId method. This will ensure that each thread calling findDespachoByTagId creates and uses its own session instance. To analyze the current problem, imagine two threads calling findDespachoByTagId at the same time. Now the static session variable will be assigned a value twice by the startTransmission method. This means one session instance is lost almost immediatly after it was created while the other one is used by two threads at the same time. Not a good thing.
But there are other problems too: there are no finally blocks that guarantee transactions are closed and database connections are released (via the closing of sessions). Also, you will probably want to use a database pool as the one provided by Hibernate is not suitable for production. I recommend you have a look at HibHik: I created this project to show a minimal stand-alone Java application using Hibernate with a database pool (HikariCP) that uses the recommended patterns and practices (mostly shown in TestDbCrud.java). Use the relevant parts in your application, than write multi-threaded unit-tests to verify your database layer (DAO) is working properly, even in the case of failure (e.g. when the database is suddenly no longer available because the network-cable was unplugged).