I am using:
org.springframework.orm.hibernate4.HibernateTransactionManager the API of which reads:
Binds a Hibernate Session from the specified factory to the thread,
potentially allowing for one thread-bound Session per factory.
Here is my code under question:
#Transactional
public void insertPerson(Person transientPerson) {
System.out.println("Current session in insert "+sessionFactory.getCurrentSession()); // Line 1
personDao.save(transientPerson);
executeConcurrently();
}
private void executeConcurrently() {
new Thread(new Runnable() {
#Transactional
public void run() {
System.out.println("This is a branew thread "+Thread.currentThread().getName());
System.out.println("In the new thread, session = "+sessionFactory.getCurrentSession()); // Line 2
}
}).start();
}
In line 1 I get the session which is obvious. However line 2's execution shows me this error:
This is a branew thread Thread-2
Exception in thread "Thread-2" org.hibernate.HibernateException: No Session found for current thread
at org.springframework.orm.hibernate4.SpringSessionContext.currentSession(SpringSessionContext.java:97)
at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:978)
at edu.sprhib.service.impl.PersonServiceImpl$1.run(PersonServiceImpl.java:55)
at java.lang.Thread.run(Thread.java:724)
What I fail to understand is why is this failing? According to my understanding, Spring should create a brand new session and associate it with the ThreadLocal of Thread-2. Is my understanding wrong or the code? I am meanwhile trying to debug the Spring code and my netbeans even after attaching source to the spring-orm jar is not being able to debug inside of it (Please note I am not very good at debugging inside framework's code).
Any help will be appreciated.
Thanks in advance,
Mustafa
Try this
#Transactional( propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public void insertPerson(Person transientPerson) {
System.out.println("Current session in insert "+sessionFactory.getCurrentSession()); // Line 1
personDao.save(transientPerson);
executeConcurrently();
}
private void executeConcurrently() {
new Thread(new Runnable() {
#Transactional
public void run() {
System.out.println("This is a branew thread "+Thread.currentThread().getName());
System.out.println("In the new thread, session = "+sessionFactory.getCurrentSession()); // Line 2
}
}).start();
}
By using Propagation.REQUIRED Spring Container handle session you don't need to worry about Session object
if your session object destroyed ,container create new one and provide session if we mention our transaction as a propagation = Propagation.REQUIRED
Related
i am making cron job like loop to do something using new thread.
when module stop, this thread keeps running, so when i deployed updated module, i'm afraid it will make duplicate thread doing similar task
#Component(immediate = true, service = ExportImportLifecycleListener.class)
public class StaticUtils extends Utils{
private StaticUtils() {}
private static class SingletonHelper{
private static final StaticUtils INSTANCE = new StaticUtils();
}
public static StaticUtils getInstance() {
return SingletonHelper.INSTANCE;
}
}
public class Utils extends BaseExportImportLifecycleListener{
public Utils() {
startTask();
}
protected Boolean CRON_START = true;
private void startTask() {
new Thread(new Runnable() {
public void run() {
while (CRON_START) {
System.out.println("test naon bae lah ");
}
}
}).start();
}
#Deactivate
protected void deactivate() {
CRON_START = false;
System.out.println(
"cron stop lah woooooooooooooooooy");
}
}
i'm using liferay 7
I have populated task that i store from db, so this thread is checking is there a task that it must do, then if it exist execute it.
I'm quite new in osgi and liferay. i've try to use scheduler and failed and also exportimportlifecycle listener but dont really get it yet
think again: Do you really need something to run all the time in the background, or do you just need some asynchronous processing in the background, when triggered? It might be better to start a background task as a one-off, that automatically terminates
Liferay provides an internal MessageBus, that you can utilize to listen to events and implement background processing, without the need for a custom thread
You're in the OSGi world, so you can utilize #Activate, #Modified, #Deactivate (from org.osgi.service.component.annotations) or use a org.osgi.framework.BundleActivator.
But, in general, it's preferable if you don't start your own thread
I am confused with Async feature introduced in Servlet 3.0 spec
From Oracle site (http://docs.oracle.com/javaee/7/tutorial/doc/servlets012.htm):
To create scalable web applications, you must ensure that no threads
associated with a request are sitting idle, so the container can use
them to process new requests.
There are two common scenarios in which a thread associated with a
request can be sitting idle.
1- The thread needs to wait for a resource to become available or process data before building the response. For example, an application
may need to query a database or access data from a remote web service
before generating the response.
2- The thread needs to wait for an event before generating the response. For example, an application may have to wait for a JMS
message, new information from another client, or new data available in
a queue before generating the response.
The first item happens a lot (nearly always, we always query db or call a remote webservice to get some data). And calling an external resource will always consume some time.
Does it mean that we should ALWAYS use servelt async feature for ALL our servelts and filter ?!
I can ask this way too, if I write all my servelts and filters async, will I lose anything (performance)?!
If above is correct the skeleton of ALL our servlets will be:
public class Work implements ServletContextListener {
private static final BlockingQueue queue = new LinkedBlockingQueue();
private volatile Thread thread;
#Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
thread = new Thread(new Runnable() {
#Override
public void run() {
while (true) {
try {
ServiceFecade.doBusiness();
AsyncContext context;
while ((context = queue.poll()) != null) {
try {
ServletResponse response = context.getResponse();
PrintWriter out = response.getWriter();
out.printf("Bussiness done");
out.flush();
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
} finally {
context.complete();
}
}
} catch (InterruptedException e) {
return;
}
}
}
});
thread.start();
}
public static void add(AsyncContext c) {
queue.add(c);
}
#Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
thread.interrupt();
}
}
We are launching a website that will have a very heavy volume for a short period of time. It is basically giving tickets. The code is written in Java, Spring & Hibernate. I want to mimic the high volume by spawning multiple threads and trying to get the ticket using JUnit test case. The problem is that in my DAO class the code just simply dies after I begin transaction. I mean there is no error trace in the log file or anything like that. Let me give some idea about the way my code is.
DAO code:
#Repository("customerTicketDAO")
public class CustomerTicketDAO extends BaseDAOImpl {// BaseDAOImpl extends HibernateDaoSupport
public void saveCustomerTicketUsingJDBC(String customerId) {
try{
getSession().getTransaction().begin(); //NOTHING HAPPENS AFTER THIS LINE OF CODE
// A select query
Query query1 = getSession().createSQLQuery("my query omitted on purpose");
.
.
// An update query
Query query2 = getSession().createSQLQuery("my query omitted on purpose");
getSession().getTransaction().commite();
} catch (Exception e) {
}
}
Runnable code:
public class InsertCustomerTicketRunnable implements Runnable {
#Autowired
private CustomerTicketDAO customerTicketDAO;
public InsertCustomerTicketRunnable(String customerId) {
this.customerId = customerId;
}
#Override
public void run() {
if (customerTicketDAO != null) {
customerTicketDAO.saveCustomerTicketUsingJDBC(customerId);
}
}
}
JUnit method:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations={"file:src/test/resources/applicationContext-test.xml"})
public class DatabaseTest {
#Before
public void init() {
sessionFactory = (SessionFactory)applicationContext.getBean("sessionFactory");
Session session = SessionFactoryUtils.getSession(sessionFactory, true);
TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(session));
customerTicketDAO = (CustomerTicketDAO)applicationContext.getBean("customerTicketDAO");
}
#After
public void end() throws Exception {
SessionHolder sessionHolder = (SessionHolder) TransactionSynchronizationManager.unbindResource(sessionFactory);
SessionFactoryUtils.closeSession(session);
}
#Test
public void saveCustomerTicketInMultipleThreads () throws Exception {
ExecutorService executor = Executors.newFixedThreadPool(NTHREDS);
for (int i=0; i<1000; i++) {
executor.submit(new InsertCustomerTicketRunnable(i));
}
// This will make the executor accept no new threads
// and finish all existing threads in the queue
executor.shutdown();
// Wait until all threads are finish
executor.awaitTermination(1, TimeUnit.SECONDS);
}
I see no data being inserted into the database. Can someone please point me as to where I am going wrong?
Thanks
Raj
SessionFactory is thread safe but Session is not. So my guess is that you need to call SessionFactoryUtils.getSession() from within each thread, so that each thread gets its own instance. You are currently calling it from the main thread, so all children threads try to share the same instance.
Naughty, naughty!
public void saveCustomerTicketUsingJDBC(String customerId) {
try {
getSession().getTransaction().begin(); //NOTHING HAPPENS AFTER THIS LINE OF CODE
.
.
} catch (Exception e) {
}
}
You should never (well, hardly ever) have an empty catch block, if there is a problem you will find that your code 'just simply dies' with no log messages. Oh look, that's what's happening ;)
At the very minimum you should log the exception, that will go a long way towards you helping you find what the problem is (and from there, the solution).
I'm trying to do some optimization in my code and would like to spawn a thread where I do a time consuming operation. During the implementation of that optimization I was running into an issue which was driving me crazy. I simplified the issue and created a test case for that specific issue: (I'm using SpringJUnit4ClassRunner so the transaction is properly started at the beginning of the testCRUD method)
Could someone help me understand why the foundParent is null in the thread ?
private Semaphore sema = new Semaphore(0, false);
private long parentId;
#Test
public void testCRUD() {
//create
DBParent parent = null;
{
parent = new DBParent();
parentDao.persist(parent);
parentId = parent.getId();
assertTrue(parentId > 0);
parentDao.flush();
}
(new Thread(
new Runnable() {
public void run()
{
System.out.println("Start adding childs !");
DBParent foundParent = parentDao.findById(parentId);
assertTrue(foundParent != null); //ASSERTION FAILS HERE !!!!
System.out.println("Releasing semaphore !");
sema.release();
System.out.println("End adding childs !");
}
})).start();
try {
System.out.println("Acquiring semaphore !");
sema.acquire();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
=============================EDITED===================================
As per one comment suggestion, I created a threadManager bean which spawn the thread. Here is the code of the threadManager:
public class ThreadManager {
#Transactional(propagation=Propagation.REQUIRES_NEW)
public void executeTask(String Name, Runnable task) {
(new Thread(task, Name)).start();
}
}
Then in the previous test, instead of staring the thread manually, I just post it in the thread manager like this:
#Autowired private ParentDao parentDao;
#Autowired private ThreadManager threadManager;
private Semaphore sema = new Semaphore(0, false);
private long parentId;
#Test
public void testCRUD() {
//create
DBParent parent = null;
{
parent = new DBParent();
parentDao.persist(parent);
parentId = parent.getId();
assertTrue(parentId > 0);
parentDao.flush();
}
threadManager.executeTask("BG processing...",
new Runnable() {
public void run()
{
System.out.println("Start adding childs !");
DBParent foundParent = parentDao.findById(parentId);
assertTrue(foundParent != null); //ASSERTION FAILS HERE !!!!
System.out.println("Releasing semaphore !");
sema.release();
System.out.println("End adding childs !");
}
});
try {
System.out.println("Acquiring semaphore !");
sema.acquire();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
Unfortunately this doesn't work either !!! :-(
The transaction context is bound to the thread. So the code in the spawned thread doesn't run in the same transaction context as the code in the initial thread. So, due to transaction isolation (the I in ACID), the spawned thread doesn't see what the initial thread's transaction is inserting in the database.
You can bind Spring transaction to a new thread, to run transactions & Hibernate/JPA access in it. But this has to be a different TX and JPA/HB session from other threads.
Spring code for OpenSessionInViewFilter, is a reasonable an example of how to bind Hibernate session to Spring's TX management. You can strip this down to fairly minimal code.
See:
org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
OpenSessionInViewFilter.doFilterInternal() -- this is where it actually binds it
TransactionSynchronizationManager.bindResource()
TransactionSynchronizationManager.unbindResource()
TransactionSynchronizationManager.getResource()
In one project (IIRC) I wrapped this functionality into a 'ServerThreadHb' class, to setup & save previous thread-bindings on construction -- with a restore() method to be called in a finally block, to restore previous bindings.
For your posted code sample, there isn't much point in running work on a separate thread -- since you synchronously wait for the work to be done. However I assume you were planning to remove that constraint & extend that functionality.
My application is Swing-based. I would like to introduce JavaFX and configure it to render a Scene on a secondary display.
I could use a JFrame to hold a JFXPanel which could hold a JFXPanel but I would like to achieve this with JavaFX API.
Subclassing com.sun.glass.ui.Application and using Application.launch(this) is not an option because the invoking thread would be blocked.
When instantiating a Stage from Swing EDT, the error I get is:
java.lang.IllegalStateException: Toolkit not initialized
Any pointers?
EDIT: Conclusions
Problem: Non-trivial Swing GUI application needs to run JavaFX components. Application's startup process initializes the GUI after starting up a dependent service layer.
Solutions
Subclass JavaFX Application class and run it in a separate thread e.g.:
public class JavaFXInitializer extends Application {
#Override
public void start(Stage stage) throws Exception {
// JavaFX should be initialized
someGlobalVar.setInitialized(true);
}
}
Sidenote: Because Application.launch() method takes a Class<? extends Application> as an argument, one has to use a global variable to signal JavaFX environment has been initialized.
Alternative approach: instantiate JFXPanel in Swing Event Dispatcher Thread:
final CountDownLatch latch = new CountDownLatch(1);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new JFXPanel(); // initializes JavaFX environment
latch.countDown();
}
});
latch.await();
By using this approach the calling thread will wait until JavaFX environment is set up.
Pick any solution you see fit. I went with the second one because it doesn't need a global variable to signal the initialization of JavaFX environment and also doesn't waste a thread.
Found a solution. If I just create a JFXPanel from Swing EDT before invoking JavaFX Platform.runLater it works.
I don't know how reliable this solution is, I might choose JFXPanel and JFrame if turns out to be unstable.
public class BootJavaFX {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JFXPanel(); // this will prepare JavaFX toolkit and environment
Platform.runLater(new Runnable() {
#Override
public void run() {
StageBuilder.create()
.scene(SceneBuilder.create()
.width(320)
.height(240)
.root(LabelBuilder.create()
.font(Font.font("Arial", 54))
.text("JavaFX")
.build())
.build())
.onCloseRequest(new EventHandler<WindowEvent>() {
#Override
public void handle(WindowEvent windowEvent) {
System.exit(0);
}
})
.build()
.show();
}
});
}
});
}
}
Since JavaFX 9, you can run JavaFX application without extending Application class, by calling Platform.startup():
Platform.startup(() ->
{
// This block will be executed on JavaFX Thread
});
This method starts the JavaFX runtime.
The only way to work with JavaFX is to subclass Application or use JFXPanel, exactly because they prepare env and toolkit.
Blocking thread can be solved by using new Thread(...).
Although I suggest to use JFXPanel if you are using JavaFX in the same VM as Swing/AWT, you can find more details here: Is it OK to use AWT with JavaFx?
I checked the source code and this is to initialize it
com.sun.javafx.application.PlatformImpl.startup(()->{});
and to exit it
com.sun.javafx.application.PlatformImpl.exit();
I used following when creating unittests for testing javaFX tableview updates
public class testingTableView {
#BeforeClass
public static void initToolkit() throws InterruptedException
{
final CountDownLatch latch = new CountDownLatch(1);
SwingUtilities.invokeLater(() -> {
new JFXPanel(); // initializes JavaFX environment
latch.countDown();
});
if (!latch.await(5L, TimeUnit.SECONDS))
throw new ExceptionInInitializerError();
}
#Test
public void updateTableView() throws Exception {
TableView<yourclassDefiningEntries> yourTable = new TableView<>();
.... do your testing stuff
}
}
even though this post is not test related, then it helped me to get my unittest to work
without the BeforeClass initToolkit, then the instantiation of TableView in the unittest would yield a message of missing toolkit
There's also way to initialize toolkit explicitly, by calling:
com.sun.javafx.application.PlatformImpl#startup(Runnable)
Little bit hacky, due to using *Impl, but is useful, if you don't want to use Application or JXFPanel for some reason.
re-posting myself from this post
private static Thread thread;
public static void main(String[] args) {
Main main = new Main();
startup(main);
thread = new Thread(main);
thread.start();
}
public static void startup(Runnable r) {
com.sun.javafx.application.PlatformImpl.startup(r);
}
#Override
public void run() {
SoundPlayer.play("BelievexBelieve.mp3");
}
This is my solution. The class is named Main and implements Runnable. Method startup(Runnable r) is the key.
Using Jack Lin’s answer, I found that it fired off the run() twice. With a few modifications that also made the answer more concise, I offer the following;
import com.sun.javafx.application.PlatformImpl;
public class MyFxTest implements Runnable {
public static void main(String[] args) {
MyFxTest main = new MyFxTest();
PlatformImpl.startup((Runnable) main);
}
#Override
public void run() {
// do your testing;
System.out.println("Here 'tis");
System.exit(0); // Optional
}
}