Month: September 2015

Hibernate / JPA : Access to DialectResolutionInfo cannot be null

Pom.xml 
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.6.Final</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>4.3.6.Final</version>
        </dependency>


Error and Cause Determination 

Deploying a new WEBApplication using Hibernate fails with : 
Deploying /usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2PC-1.0.war
"{\"JBAS014671: Failed services\" => {\"jboss.persistenceunit.\\\"WFJPA2PC-1.0.war#RacBankBHibPU\\\"\" 
  => \"org.jboss.msc.service.StartException in service jboss.persistenceunit.\\\"WFJPA2PC-1.0.war#RacBankBHibPU\\\": 
     org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
     Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set\"}}"

Cause : Oracle RAC database was down ! 

Fix : Add hibernate.dialect to your persistence.xml 
   <persistence-unit name="RacBankBHibPU" transaction-type="JTA">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>java:/jboss/datasources/xa_rac12g_bankb</jta-data-source>
        <class>com.hhu.wfjpa2pc.Accounts</class>
        <properties>
            <property name="hibernate.transaction.jta.platform"
                 value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
        </properties>
    </persistence-unit>

-> Now application can be redeployed 
-> Application now starts but throws the following stack 
08:55:04.761 javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/xa_rac12g_bankb
08:55:04.762 java.sql.SQLException: javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/xa_rac12g_bankb
    at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:154)
    at com.hhu.wfjpa2pc.Jpa2pcTest.getRacInfoDS(Jpa2pcTest.java:398)
    at com.hhu.wfjpa2pc.Jpa2pcTest.getRacInfo(Jpa2pcTest.java:376)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.

-> With above Stack we easily can figure out that we need to start our RAC DB

Copy a Maven based JPA project to new project folder

New Project Details

ArtifactId                   : WFJPA2PC
New Project Home             : /home/oracle/NetBeansProjects/GIT/WFJPA2PC 
New persistence.xml location :  /home/oracle/NetBeansProjects/GIT/WFJPA2PC/src/main/resources/META-INF/persistence.xml Your old and working project should have a working pom.xml and persistence.xml

Modify and copy pom,xml

Modify artifactId and name in your pom.xml 
    <artifactId>WFJPA2PC</artifactId>
    <name>WFJPA2PC</name>

Copy pom.xml to your new Project Folder 
$ cp pom.xml   /home/oracle/NetBeansProjects/GIT/WFJPA2PC

Add JSF support to our project 
Project -> Properties -> Framework -> Add JavaServerFaces 
                                   -> Components -> PrimeFaces

Create new Entity Classes

Create new Entity Classes as needed [ in our sample we use Entity Class : Accounts 

Source package -> New -> EnititY Class form Database 
  -> Select Datasource 
  -> Select Table Name : Accounts  
  -> Add 
  -> Finish

Create a new JPA persistence.xml and copy over the working persistence.xml

Netbeans : File -> NEW ->  Persistence Unit 

Locate your Persistence Location of persistence.xml:
  /home/oracle/NetBeansProjects/GIT/WFJPA2PC/src/main/resources/META-INF/persistence.xml

-> Copy over your new RAC XA persistence.xml to   src/main/resources/META-INF/persistence.xml
   and add your newly created Entitly Classes    

Sample for a Hibernate persistence.xml with Entity Class : Accounts
<?xml version="1.0"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">

    <persistence-unit name="RacBankAHibPU" transaction-type="JTA">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <jta-data-source>java:/jboss/datasources/xa_rac12g_banka</jta-data-source>
        <class>com.hhu.wfjpa2pc.Accounts</class>
        <properties>
            <property name="hibernate.transaction.jta.platform"
                 value="org.hibernate.service.jta.platform.internal.JBossAppServerJtaPlatform" />
            <property name="hibernate.show_sql" value="true" />
        </properties>
</persistence>

Details on HttpSession Object

Overview

  • HTTP is a stateless protocol
  • To keep JAVA object available longer than the duration of a HTTP request  each Object is stored within the HTTP session object. This is called Session tracking feature.
  • Typical technical solutions  for Session Tracking are
      • Cookies
      • URL rewriting

    Hidden form fields.

 

Why and how should you protect your HTTP session object

  • HttpSession object is not thread safe
  • Browser Tabbing, Fast Page Reloading  and async. AJAX request may give you concurrent access to the same HttpSession object
  • There is no guarantee that multiple calls to HttpServletRequest.getSession() will return the same HttpSession object .
  • Don’t synchronize on HttpSession object as this object may be recreated by certain containers
  • Synchronize on immutable object returned by :  session.getId().intern()

Reference

Creating a HTTP session using cookies

JSESSIONID cookie is created/sent when session is created. Session is created when your code calls request.getSession() 
or request.getSession(true) for the first time. If you just want get session, but not create it if it doesn't exists, 
use request.getSession(false) -- this will return you a session or null. In this case, new session is not created, 
and JSESSIONID cookie is not sent. (This also means that session isn't necessarily created on first request... you 
and your code is in control when the session is created)

Understanding Browser Session and HTTP Session Object

Using Browser tabbing with firefox  

Start a first Browser session and run their initial  HTTP POST to create the HTTP session by running timeoutTest() :
Session 1:  $ firefox http://localhost:8180/WFJPA2EL-1.0/ 
12:56:42.530 timeoutTest() - NEW Session  - ID zjiDVDLbFkQYhJ4bARWTmP6P - Access Count: 0- i
             JSESSIONID cookie: zjiDVDLbFkQYhJ4bARWTmP6P.wls1 - MaxIncativeInterval:  10 - 
             Last AccessedTime: 12:56:34.636 - Cookie MaxAge: -1

Now start as new Browser Tab using the same URL  and run the HTTP Post request again 
Session 2: $ firefox http://localhost:8180/WFJPA2EL-1.0/
12:56:47.856 timeoutTest() - WELCOME Back Session   - ID zjiDVDLbFkQYhJ4bARWTmP6P - Access Count: 1- 
             JSESSIONID cookie: zjiDVDLbFkQYhJ4bARWTmP6P.wls1 - MaxIncativeInterval:  10 - 
             Last AccessedTime: 12:56:42.547 - Cookie MaxAge: -1

- The second request doesn't create a new HTTP session object
- Instead browser session are uing the HTTP Session object 
- Thats is why you should serialize access to the HTTP session object as multiple threads may use this JAVA object !
 

Using a different Firefox profile or different Host name will create different HTTP Objects:

Session 1: $ firefox http://localhost:8180/WFJPA2EL-1.0/
10:06:59.096 timeoutTest() - NEW Session  - ID O3tl4IqIDCAGWB16O52HO6h6 - Access Count: 0- 
             JSESSIONID cookie: O3tl4IqIDCAGWB16O52HO6h6.wls1 - MaxIncativeInterval:  10 - 
             Last AccessedTime: 10:06:53.374 - Cookie MaxAge: -1

Session 2: $  firefox http://wls1:8180/WFJPA2EL-1.0/
10:07:42.817 timeoutTest() - NEW Session  - ID 6kqRcL-DDpKCywOqrq3wo8yB - Access Count: 0- 
             JSESSIONID cookie: 6kqRcL-DDpKCywOqrq3wo8yB.wls1 - MaxIncativeInterval:  10 - 
             Last AccessedTime: 10:07:37.164 - Cookie MaxAge: -1

- Using a different hostname [ or Firefox Profiles ] will create a new HTTP session object !

HTTP session object details

  • A HTTP Session objects stores data about Cookies and Attributes
  • The JSESSIONID is the cookie for implementing the Session Feature
  • The accessCount attribute tracks how often this session is reused by an HTTP request
10:19:27.673  timeoutTest() - WELCOME Back Session   - ID fwdaf1VInpfsA-20853SiT_F - Access Count: 1- 
              JSESSIONID cookie: fwdaf1VInpfsA-20853SiT_F.wls1 - MaxIncativeInterval:  10 - 
              Last AccessedTime: 10:19:23.205 - Cookie MaxAge: -1
10:19:27.674  attr  = accessCount      value = 1
10:19:27.675  Cookie   name  = JSESSIONID   value = fwdaf1VInpfsA-20853SiT_F.wls1    Cookie MaxAge = -1
Details:
 - Cookie MaxAge = -1       -> No Cookie Timeout
 - MaxIncativeInterval:  10 -> HTTP session timeout [ 10 seconds ] 
 - accsessCount             -> HTTP object stored within HTTP session object

Java Code to display HTTP session details and set and read attributes

public void trackSession(HttpSession session, String methodName)
      {
        final Object lock = session.getId().intern();  
        synchronized(lock) 
          {
            String heading = null;
            accessCount =    (Integer)session.getAttribute("accessCount");
            if (accessCount == null) 
              {
                accessCount = new Integer(0);
                heading =  methodName + " - NEW Session";
              } 
            else 
              {
                heading =  methodName + " - WELCOME Back Session ";
                accessCount = new Integer(accessCount.intValue() + 1);
              }
            String jSessionId = "JSESSIONID not found";
            int jSessionMaxAge = 0;
            HttpServletRequest req = (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest(); 

                // There no API to return JESSIONID cookie - we need to loop throught the Cookie Arrary 
            Cookie[] cookies = req.getCookies();
            for(Cookie cookie : cookies)
              {
                if("JSESSIONID".equals(cookie.getName()))
                  {    
                    jSessionId = cookie.getValue();
                    jSessionMaxAge = cookie.getMaxAge();
                               }
               }
                       
            session.setAttribute("accessCount", accessCount);
            setSessionInfo(heading +  "  - ID "  + session.getId() + " - Access Count: " + accessCount.intValue() 
                 + "- JSESSIONID cookie: " + jSessionId + " - MaxIncativeInterval:  " + session.getMaxInactiveInterval()
                 + " - Last AccessedTime: " + Tools.getTime2(session.getLastAccessedTime()) + " - Cookie MaxAge: " + jSessionMaxAge);
            
                // display Session details : Cookies and 
            if (displaySessionDetails )
              {   
                Enumeration es = session.getAttributeNames();
                while (es.hasMoreElements())
                  {
                    String attr = (String)es.nextElement();
                    Object value = session.getValue(attr);
                    setSessionInfo("      attr  = "+ attr +"      value = "+ value);
                  } 

                for (Cookie cookie : cookies) 
                  {
                    String cookieName = cookie.getName();
                    String cookieValue = cookie.getValue();
                    setSessionInfo("    Cookie   name  = "+  cookieName+"   value = "+ cookieValue + "    Cookie MaxAge = " +  cookie.getMaxAge());
                  }    
              }
          }                                  
      }

How to deal with HTTP Session Timeout – a JSF sample

  • For security and memory management, sessions need to be invalidated at a certain time
There are two related methods in HttpSession.
- HttpSession.invalidate() 
  By invoking invalidate(), the session will be invalidated immediately. 
  This is useful for the case such as logout.
- HttpSession.setMaxInactiveInterval(int interval)
 The method setMaxInactiveInterval(int interval) allows us to configure the time (in seconds) 
 between client requests before the servlet container will invalidate the session.
 That is, an idle session will be invalidated after the specified time.

See https://weblogs.java.net/blog/swchan2/archive/2013/08/29/when-httpsession-invalidated

HTTP session timemout can be configured via web.xml 

web.xml sample 
 <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>

setMaxInactiveInterval() sample
    HttpSession session = (HttpSession) FacesContext.getCurrentInstance().getExternalContext().getSession(true);
    if ( session == null)
      {
        throw new IllegalArgumentException(methodName+ ": Could not get HTTP session : ");    
      }
    session.setMaxInactiveInterval(5);

Note setMaxInactiveInterval configures the time (in seconds) between client requests 
and before the servlet container will invalidate the session.

After your initial HTTP GET request wait 5 seconds and send a HTTP POST request. 
This HTTP POST request will fail with:   
  javax.faces.application.ViewExpiredException: viewId:/index.xhtml - 
    View /index.xhtml could not be restored.
    at com.sun.faces.lifecycle.RestoreViewPhase.execute(RestoreViewPhase.java:210)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:121)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)

Fix : You may Add an error page to your web.xml file
    <error-page>
        <exception-type>javax.faces.application.ViewExpiredException</exception-type>
        <location>/faces/index.xhtml</location>
    </error-page>

Further details on Thread Safety

Never assign any request or session scoped data as an instance variable of a servlet or filter. 
It will be shared among all other requests in other sessions. 
That's threadunsafe! The below example illustrates that:

public class ExampleServlet extends HttpServlet 
  {
    private Object thisIsNOTThreadSafe;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
      {
        Object thisIsThreadSafe;

        thisIsNOTThreadSafe = request.getParameter("foo"); // BAD!! Shared among all requests!
        thisIsThreadSafe = request.getParameter("foo"); // OK, this is thread safe.
     } 
 }

Reference

 

 

A deeper dive into Transaction Timeouts with JEE7,Wildfly and Oracle RAC

Potential Transaction Timeouts in a JEE7 / RAC 12.1.0.2 env

  1.  JTA Transaction Timeout triggering an OracleXAResource.rollback operation on our TM side [ Wildfly 8.2 ]
  2. JTA Transaction Timeout occuring on the RM side [ ORA-24756 ]
  3. DISTRIBUTED LOCK TIMEOUT occuring on the RM side [ ORA-2049 ]
  4. HTTPSession Object Timeout

Rule of Thumb

  •  JTA transaction timeout  <  DISTRIBUTED_LOCK_TIMEOUT  <  HTTP Session Timeout
  • In a working JTA env we only want to see JTA timeouts triggered by our TM  [ see 1. ]

Overview Bean Managed Transaction with JTA

  • Each JTA transaction is associated with an Execution Thread
  • Only a single Transaction can be active within an  Execution Thread
  • If one Transaction is active the user can’t start an new one until the TX was committed suspended or rolled back
  • The setTransactionTimeout() method causing  the transaction to roll back after reaching the timeout limit
  • Do not invoke the getRollbackOnly and setRollbackOnly methods of the EJBContext interface in bean-managed transactions [ BMT ]
  • For bean-managed transactions, invoke the getStatus and rollback methods of the UserTransaction interface
  • If a session times out within Oracle, then the Oracle database Process Monitor (PMON) will delete the transaction branch if not prepared or cause the transaction to become in-doubt if prepared.
  • We can track the Transaction Timeout at RM side using Event 10246
         alter system set event=”10246 trace name context forever, level 1″ scope=spfile sid=’*’;
  • If the PMON terminates the transaction branch you should get error: ORA-24756: transaction does not exist
  • If the Transaction can’t get a database lock you should get error: ORA-02049: timeout: distributed transaction waiting for lock
  • During this JPA test we use OnePhaseCommit [ means no 2PC / no prepare call ]
  • We always want that our TM is controlling the Transaction
  • If runnig with correct timeout settings we should not see any ORA-2049 or ORA-24756 errors

How to track the XA transaction at database level

  • FORMATID, GLOBALID, BRANCHID build our  XA Xid
  • TIGHTLY COUPLED means we serialize using a DX lock [ can lead to a performance problem ]  and can use RAC ClusterWide Transaction Feature
  • PREPARECOUNT=0 this Tx is not yet prepared
  • STATE ACTIVE means this transaction is active
SQL> select FORMATID, GLOBALID, BRANCHID, BRANCHES, REFCOUNT, PREPARECOUNT, STATE, 
     FLAGS, COUPLING  from v$global_transaction;

  FORMATID GLOBALID
---------- ----------------------------------------------------------------
BRANCHID
--------------------------------------------------------------------------------------------------------------------------------
  BRANCHES   REFCOUNT PREPARECOUNT STATE                       FLAGS COUPLING
---------- ---------- ------------ -------------------------------------- ---------- ---------------
    131077 00000000000000000000FFFFC0A805C935ABDAA855FBBB600000046931
00000000000000000000FFFFC0A805C935ABDAA855FBBB600000046C0000000200000000
     1        1         0 ACTIVE                       0 TIGHTLY COUPLED

TEST 1:  Testing global JTA Timeout

  • The service routine will run 60 seconds before committing the data
  • The JPA timeout will rollback the transaction after the JTA timeout [ 30 seconds ]
  • The Transaction Reaper Wildfly Thread will rollback the transaction after 30 second
  • Later on the commit fails as we don’t run inside a transaction anymore
Setup
HTTP Session Timeout       : 1800 seconds
JTA Timeout                :   30 seconds
ut.setTransactionTimeout() :  not active
Service routine sleep      :   60 seconds 

Setup and verify  JTA Transaction Timeout : 30 seconds:

$ $WILDFLY_HOME/bin/jboss-cli.sh  --connect --controller=localhost:9990 '/subsystem=transactions/:write-attribute(name=default-timeout,value=30)';
{
    "outcome" => "success",
    "result" => 30,
    "response-headers" => {"process-state" => "reload-required"}
}

$  $WILDFLY_HOME/bin/jboss-cli.sh  --connect --controller=localhost:9990 '/subsystem=transactions/:read-attribute(name=default-timeout)'
{
    "outcome" => "success",
    "result" => 30
}

-> Restart Wildfly
-> Run test test case
 
Wildfly Logs:
10:18:52,211 INFO  [stdout] (default task-15) +++ HttpSessionListenerImpl:: sessionCreated()....
10:18:55,489 INFO  [org.eclipse.persistence.connection] (default task-36) 
        Connected: jdbc:oracle:thin:@ract2-scan.grid12c.example.com:1521/banka
    User: SCOTT
    Database: Oracle  Version: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
    Driver: Oracle JDBC driver  Version: 12.1.0.2.0
...
2015-09-17 10:18:55,500 INFO  [org.eclipse.persistence.connection] (default task-17) vfs:/usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2EL-1.0.war/WEB-INF/classes/_jpaELPU login successful
10:19:27,365 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper) ARJUNA012117: TransactionReaper::check timeout for TX 0:ffffc0a805c9:6a216e79:55fa71c5:72 in state  RUN
10:19:27,367 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012095: Abort of action id 0:ffffc0a805c9:6a216e79:55fa71c5:72 invoked while multiple threads active within it.
10:19:27,368 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012108: CheckedAction::check - atomic action 0:ffffc0a805c9:6a216e79:55fa71c5:72 aborting with 1 threads active!
10:19:27,383 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012121: TransactionReaper::doCancellations worker Thread[Transaction Reaper Worker 0,5,main] successfully canceled TX 0:ffffc0a805c9:6a216e79:55fa71c5:72
10:19:57,381 WARN  [com.arjuna.ats.arjuna] (default task-17) ARJUNA012077: Abort called on already aborted atomic action 0:ffffc0a805c9:6a216e79:55fa71c5:72

-> JPA connection returned at 10:18:55
   About 32 seconds later the global JTA timeout kicks in and terminates the transaction a

Stack :
10:19:57.382 Error in top level function: timeoutTest()
10:19:57.384 ARJUNA016102: The transaction is not active! Uid is 0:ffffc0a805c9:6a216e79:55fa71c5:72
10:19:57.385 javax.transaction.RollbackException: ARJUNA016102: The transaction is not active! Uid is 0:ffffc0a805c9:6a216e79:55fa71c5:72
    at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1156)
    at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126)
    at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:75)
    at org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:173)
    at com.hhu.wfjpa2el.JPATestBean.timeoutTest(JPATestBean.java:456)

TEST 2: Overriding global JTA Timeout with  ut.setTransactionTimeout()

  • This test is similar to TEST 1
  • it only overrides the JTA transaction timeout with setTransactionTimeout()
Setup 
HTTP Session Timeout       : 1800 seconds
JTA Timeout                :   30 seconds
ut.setTransactionTimeout() :   15 seconds
Service routine sleep      :   60 seconds 

Java Code 
     ...
     ut  = (UserTransaction)new InitialContext().lookup("java:comp/UserTransaction");          
     ut.setTransactionTimeout(getTxTimeout());                     
     ut.begin();
     ...

Wildfly Log :
2015-09-17 10:58:58,426 INFO  [org.eclipse.persistence.connection] (default task-36) 
        Connected: jdbc:oracle:thin:@ract2-scan.grid12c.example.com:1521/banka
    User: SCOTT
    Database: Oracle  Version: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
    Driver: Oracle JDBC driver  Version: 12.1.0.2.0
2015-09-17 10:58:58,431 INFO  [org.eclipse.persistence.connection] (default task-36) vfs:/usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2EL-1.0.war/WEB-INF/classes/_jpaELPU login successful
2015-09-17 10:59:15,094 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper) ARJUNA012117: TransactionReaper::check timeout for TX 0:ffffc0a805c9:6a216e79:55fa71c5:11a in state  RUN
2015-09-17 10:59:15,096 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012095: Abort of action id 0:ffffc0a805c9:6a216e79:55fa71c5:11a invoked while multiple threads active within it.
2015-09-17 10:59:15,097 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012108: CheckedAction::check - atomic action 0:ffffc0a805c9:6a216e79:55fa71c5:11a aborting with 1 threads active!
2015-09-17 10:59:15,115 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012121: TransactionReaper::doCancellations worker Thread[Transaction Reaper Worker 0,5,main] successfully canceled TX 0:ffffc0a805c9:6a216e79:55fa71c5:11a

-> JPA connection returned at  10:58:58,
-> About 17 seconds later the Timeout value set by ut.setTransactionTimeout()  kicks in and terminates the transaction a
-> As in TEST 1 the commit fail with a similar stack  

TEST 3 : Stop all TM Threads and  let the RM [ Resource Manager ] terminate the transaction

  • In this test set a breakpoint at OracleXAResource.commit to stop all WildFly Threads
  • This will avoid that any WildFly Thread is running a ROLLBACK
  • You may read following article to setup a XA Breakpoints with Netbeans
  • As no client ROLLBACK operation can terminate the transaction PMON takes over control and terminates the TX
Setup 
HTTP Session Timeout       : 1800 seconds
JTA Timeout                :   30 seconds
ut.setTransactionTimeout() :   20 seconds
Service routine sleep      :  not active

PMON Tracing 
Enable PMON tracing   for our RAC 12.1.0.2 database 
SQL> alter system set event="10246 trace name context forever, level 1" scope=spfile sid='*';
SQL> startup force
SQL> show parameter event
SQL>
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
even t                                string      10246 trace name context forever, level 1

PMON trace 
*** 2015-09-18 11:47:04.143
 bno=1 timeout=20 dtime=1442569601 ctime=1442569623 ser=1 evt=1
ksuprog() called at ktur.c:3906
[claim lock 0x74cb0100 for dead session/txn in procp 0x76b29430.18437][hist x424224a1]
deleted branch 0x72558fc0 in first attempt
PMON last posted from location=FILE:/ade/b/2502491802/oracle/rdbms/src/hdir/ksa2.h LINE:294 ID:ksasnr, process=47, post_num=41

-> timeout=20  translates to our JTA timing set with  ut.setTransactionTimeout(20); 
-> The RM ( Oracle Database ) has terminated this Transaction 
-> The transaction timeout was to 20 [ timeout=20 ] 

Errors  :
  XA Failure     : XAException.XAER_NOTA: oracle.jdbc.xa.OracleXAException
  ORacle Failure : java.sql.SQLException: ORA-24756: transaction does not exist
 
Java Stack :
Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options jndiName=java:jboss/datasources/xa_rac12g_banka]) failed with exception XAException.XAER_NOTA: oracle.jdbc.xa.OracleXAException
    at oracle.jdbc.driver.T4CXAResource.kputxrec(T4CXAResource.java:965)
    at oracle.jdbc.driver.T4CXAResource.doCommit(T4CXAResource.java:454)
    at oracle.jdbc.xa.client.OracleXAResource.commit(OracleXAResource.java:583)
    at org.jboss.jca.adapters.jdbc.xa.XAManagedConnection.commit(XAManagedConnection.java:338)
    at org.jboss.jca.core.tx.jbossts.XAResourceWrapperImpl.commit(XAResourceWrapperImpl.java:107)
    at com.arjuna.ats.internal.jta.resources.arjunacore.XAResourceRecord.topLevelOnePhaseCommit(XAResourceRecord.java:679) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.arjuna.coordinator.BasicAction.onePhaseCommit(BasicAction.java:2317) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.arjuna.coordinator.BasicAction.End(BasicAction.java:1475) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:96) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:162) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1166) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126) [jbossjta-4.16.6.Final.jar:]
    at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:75)
    at org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:173)
    at com.hhu.wfjpa2el.JPATestBean.timeoutTest(JPATestBean.java:466) [classes:]

Caused by: java.sql.SQLException: ORA-24756: transaction does not exist
    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:450)
    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:392)
    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:385)
    at oracle.jdbc.driver.T4CTTIfun.processError(T4CTTIfun.java:1018)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:522)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:257)
    at oracle.jdbc.driver.T4CTTIOtxen.doOTXEN(T4CTTIOtxen.java:166)
    at oracle.jdbc.driver.T4CXAResource.doTransaction(T4CXAResource.java:757)
    at oracle.jdbc.driver.T4CXAResource.doCommit(T4CXAResource.java:428)

TEST 4 : Understand and Testing DISTRIBUTED_LOCK_TIMEOUT

  • DISTRIBUTED_LOCK_TIMEOUT default value is 60 seconds
  • If a DML can get the lock within DISTRIBUTED_LOCK_TIMEOUT ORA-2049 is thrown
If the locking transaction runs for longer than the database DISTRIBUTED_LOCK_TIMEOUT  (e.g. a single phase trans
action with no timeout) a deadlock  type situation occurs and the XA / Oracle distributed transactions can fail 
with “ORA-02049: timeout: distributed transaction waiting for lock”. If the ordering of timeouts is correct, then 
this error should never be received within a XA distributed transaction since the TM timeout should be exceeded 
before the DISTRIBUTED_LOCK_TIMEOUT is reached

Setup 
HTTP Session Timeout       : 1800 seconds
JTA Timeout                :   30 seconds
ut.setTransactionTimeout() :  120 seconds
DISTRIBUTED_LOCK_TIMEOUT   :   60 seconds

As ut.setTransactionTimeout() < DISTRIBUTED_LOCK_TIMEOUT  the database will throw ORA-2049 errors


Prepare test  
SQL>  show parameter dist
NAME                     TYPE     VALUE
------------------------------------ ----------- ------------------------------
distributed_lock_timeout         integer     60
Note PMON runs only every 60 seconds so we can see a delay between 60 and 120 seconds untill we hot ORA-2049

Lock the records
SQL> select * from emp2 for update;
     EMPNO ENAME      JOB           SAL
---------- ---------- --------- ----------
      9997 Helmut     Progr.         63206

Our JPA code will start a BMT and update the same record resulting in a ORA-2049 error 
  UPDATE EMP2 SET SAL = ? WHERE (EMPNO = ?)

Call flow 
  ut.begin()
  JPA update gets blocked untill we hit ORA-2049 error

Verify the Transation status before getting ORA-2049
SQL> select FORMATID, GLOBALID, BRANCHID, BRANCHES, REFCOUNT, PREPARECOUNT, STATE, FLAGS, COUPLING
           from v$global_transaction;

  FORMATID GLOBALID
---------- ----------------------------------------------------------------
BRANCHID
--------------------------------------------------------------------------------------------------------------------------------
  BRANCHES   REFCOUNT PREPARECOUNT STATE                       FLAGS COUPLING
---------- ---------- ------------ -------------------------------------- ---------- ---------------
    131077 00000000000000000000FFFFC0A805C935ABDAA855FBBB60000003C931
00000000000000000000FFFFC0A805C935ABDAA855FBBB60000003CC0000000200000000
     1        1         0 ACTIVE                       0 TIGHTLY COUPLED


Error Stacks 
12:06:04.535 Error in top level function: timeoutTest()

12:06:04.536 Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLSyntaxErrorException: ORA-02049: timeout: distributed transaction waiting for lock

Error Code: 2049
Call: UPDATE EMP2 SET SAL = ? WHERE (EMPNO = ?)
    bind => [2 parameters bound]
Query: UpdateObjectQuery(com.hhu.wfjpa2el.Emp2[ empno=9997 ])

12:06:04.539 javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLSyntaxErrorException: ORA-02049: timeout: distributed transaction waiting for lock

Error Code: 2049
Call: UPDATE EMP2 SET SAL = ? WHERE (EMPNO = ?)
    bind => [2 parameters bound]
Query: UpdateObjectQuery(com.hhu.wfjpa2el.Emp2[ empno=9997 ])
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.flush(EntityManagerImpl.java:868)
    at com.hhu.wfjpa2el.JPATestBean.timeoutTest(JPATestBean.java:472)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)


2015-09-18 12:27:05,295 WARN  [com.arjuna.ats.jta] (Periodic Recovery) ARJUNA016037: Could not find new XAResource to use 
for recovering non-serializable XAResource XAResourceRecord < resource:null, txid:< formatId=131077, gtrid_length=29, bqual_length=36, 
  tx_uid=0:ffffc0a805c9:35abdaa8:55fbbb60:49, node_name=1, branch_uid=0:ffffc0a805c9:35abdaa8:55fbbb60:4c, subordinatenodename=null, 
  eis_name=java:jboss/datasources/xa_rac12g_banka >, heuristic:   TwoPhaseOutcome.FINISH_OK, product: 
  Oracle/Oracle Database 12c12:27:05,295 WARN  [com.arjuna.ats.jta] (Periodic Recovery) ARJUNA016037: 
    Could not find new XAResource to use for recovering non-serializable XAResource XAResourceRecord 
       < resource:null, txid:< formatId=131077, gtrid_length=29, bqual_length=36, tx_uid=0:ffffc0a805c9:35abdaa8:55fbbb60:49, 
       node_name=1, branch_uid=0:ffffc0a805c9:35abdaa8:55fbbb60:4c, subordinatenodename=null, eis_name=java:jboss/datasources/xa_rac12g_banka >, 
    heuristic: TwoPhaseOutcome.FINISH_OK, product: Oracle/Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production


As we don't rollback the Transaction in our sample this is done by the Transaction Reaper Wildfly thread 
"Transaction Reaper Worker 1"
oracle.jdbc.xa.client.OracleXAResource.rollback(OracleXAResource.java:945)
org.jboss.jca.adapters.jdbc.xa.XAManagedConnection.rollback(XAManagedConnection.java:346)
org.jboss.jca.core.tx.jbossts.XAResourceWrapperImpl.rollback(XAResourceWrapperImpl.java:196)
com.arjuna.ats.internal.jta.resources.arjunacore.XAResourceRecord.topLevelAbort(XAResourceRecord.java:355)
com.arjuna.ats.arjuna.coordinator.BasicAction.doAbort(BasicAction.java:2939)
com.arjuna.ats.arjuna.coordinator.BasicAction.doAbort(BasicAction.java:2918)
com.arjuna.ats.arjuna.coordinator.BasicAction.Abort(BasicAction.java:1632)
com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.cancel(TwoPhaseCoordinator.java:116)
com.arjuna.ats.arjuna.AtomicAction.cancel(AtomicAction.java:215)
com.arjuna.ats.arjuna.coordinator.TransactionReaper.doCancellations(TransactionReaper.java:377)
com.arjuna.ats.internal.arjuna.coordinator.ReaperWorkerThread.run(ReaperWorkerThread.java:78)

TEST 5 : Testing HTTP session Timeout

  • In this test the service routine runs 5 seconds longer [ see sleep 20 s ] compared to our HTTP session limit
  • When returned from our service routine the HTTP session object was already deleted
  • Again The XA transaction will be rolled back by the Wildfly Transaction Reaper Worker Thread
Setup :
HTTP Session Timeout                :   15 seconds
JTA Timeout                         :   30 seconds
ut.setTransactionTimeout()          :   not active
Service routine duration/sleep      :   20 seconds 

Java Code : 
  HttpSession session;
  ...
  session.setMaxInactiveInterval(getSessTimeout());

Wildfly Log reports :
15:55:35,839 SEVERE [javax.enterprise.resource.webcontainer.jsf.application] (default task-5) Error Rendering View[/index.xhtml]: java.lang.IllegalStateException: UT000010: Session not found Iu250lTlBLzIu_FlPHWNxq5_
    at io.undertow.server.session.InMemorySessionManager$SessionImpl.getAttribute(InMemorySessionManager.java:353) [undertow-core-1.1.0.Final.jar:1.1.0.Final]
    at io.undertow.servlet.spec.HttpSessionImpl.getAttribute(HttpSessionImpl.java:121) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]
    at com.sun.faces.context.SessionMap.get(SessionMap.java:118) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.getResponseEncoding(FaceletViewHandlingStrategy.java:1271) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.createResponseWriter(FaceletViewHandlingStrategy.java:1182) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:403) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337) [jboss-jsf-api_2.2_spec-2.2.8.jar:2.2.8]
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:337) [jboss-jsf-api_2.2_spec-2.2.8.jar:2.2.8]
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219) [jsf-impl-2.2.8-jbossorg-1.jar:]
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647) [jboss-jsf-api_2.2_spec-2.2.8.jar:2.2.8]
    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.1.0.Final.jar:1.1.0.Final]

Which Thread is rolling back the transaction ?

Setting a breakpoint on OracleXAResource.rollback shows that the Transaction Reaper is rolling back the Transaction 
"Transaction Reaper Worker 2"
oracle.jdbc.xa.client.OracleXAResource.rollback(OracleXAResource.java:945)
org.jboss.jca.adapters.jdbc.xa.XAManagedConnection.rollback(XAManagedConnection.java:346)
org.jboss.jca.core.tx.jbossts.XAResourceWrapperImpl.rollback(XAResourceWrapperImpl.java:196)
com.arjuna.ats.internal.jta.resources.arjunacore.XAResourceRecord.topLevelAbort(XAResourceRecord.java:355)
com.arjuna.ats.arjuna.coordinator.BasicAction.doAbort(BasicAction.java:2939)
com.arjuna.ats.arjuna.coordinator.BasicAction.doAbort(BasicAction.java:2918)
com.arjuna.ats.arjuna.coordinator.BasicAction.Abort(BasicAction.java:1632)
com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.cancel(TwoPhaseCoordinator.java:116)
com.arjuna.ats.arjuna.AtomicAction.cancel(AtomicAction.java:215)
com.arjuna.ats.arjuna.coordinator.TransactionReaper.doCancellations(TransactionReaper.java:377)
com.arjuna.ats.internal.arjuna.coordinator.ReaperWorkerThread.run(ReaperWorkerThread.java:78)

JAVA Test CODE

 public String timeoutTest()  
      {
        EntityManager em;
        String methodName = "timeoutTest()";
        UserTransaction ut =null;
        cleanall();
          try
          {    
            setRunTimeInfo("Calling " + methodName  +  " in progress .. ");
            setRunTimeInfo("Requesting Entity Manager.. ");
            
            HttpSession session = (HttpSession) FacesContext.getCurrentInstance().getExternalContext().getSession(true);
            if ( session == null)
              {
                throw new IllegalArgumentException(methodName+ ": Could not get HTTP session : ");    
              }                        
            /*
                HTTP session object is not thread safe. We need to syncronoise on session id.
                For datails read :  http://yet-another-dev.blogspot.de/2009/08/synchronizing-httpsession.html
            */
            final Object lock = session.getId().intern();  
            Emp2 e = null;
            long eno = -1;
            synchronized(lock) 
              {
                
                if ( getTestMode() == 4)
                  {
                    setSessTimeout(15);
                    setTxTimeout(100); 
                    session.setMaxInactiveInterval(getSessTimeout());
                    setRunTimeInfo("HTTP SessionTimeout() set to: " 
                            + getSessTimeout()  + " seconds");
                  }
                
                if ( getTestMode() == 3)
                  {
                    setTxTimeout(100);  
                    //setSessTimeout(15);
                    setRunTimeInfo("ut.setTransactionTimeout() set to: " 
                            + getTxTimeout()  + " seconds");
                    
                  } 
                
                if ( getTestMode() == 2)
                  {
                    setTxTimeout(20);  
                    //setSessTimeout(15);
                    setRunTimeInfo("Overriding global JTA Timeout : 30 seconds with  ut.setTransactionTimeout() set to: " 
                            + getTxTimeout()  + " seconds");
                    
                  }  
                if ( getTestMode() == 1)
                  {
                    setTxTimeout(15);    
                    setRunTimeInfo("Overriding global JTA Timeout : 30 seconds with  ut.setTransactionTimeout() set to: " 
                            + getTxTimeout()  + " seconds");
                    
                  }    
                if ( getTestMode() == 0)
                  {
                    setRunTimeInfo("Testing global JTA Timeout : 30 seconds");
                  }   
                
                // startAndSuspendSimple(session);
                trackSession(session, methodName );
                em=getEntityManager();
                eno= getEmpno();              
                setRunTimeInfo("Inside " + methodName + " - Empno: " + eno + " - Thread: " +  Thread.currentThread().getName());                             
                e = em.find(Emp2.class, eno );
                checkEntity(e,em);
                e.setSal(e.getSal().add(increaseSalStep1) );
                ut  = (UserTransaction)new InitialContext().lookup("java:comp/UserTransaction");
                String tx_status_before = returnTXStatus(ut);                  
            
                if ( getTestMode() == 1 ||  getTestMode() == 2 || getTestMode() == 3 )
                  {
                    ut.setTransactionTimeout(getTxTimeout());
                    setRunTimeInfo("JTA Transation started with  ut.setTransactionTimeout() set to  : " + getTxTimeout() + " seconds");
                  }    
                ut.begin();
                em.joinTransaction();
                e.setSal(e.getSal().add(increaseSalStep1) );
                em.merge(e);
                    // Update database record 
                em.flush();
                int sleep_time = 20;
                sleep(sleep_time*1000);
               
                ut.commit();
                setRunTimeInfo("Commit Called ");
               
                String tx_status_after = returnTXStatus(ut);     
                setRunTimeInfo(methodName + ": em.flush() // but NO ut.commit   - Before " + tx_status_before
                    + " - After " + tx_status_after);
                checkEntity(e,em);
                setRunTimeInfo("Closing  Entity Manager.. !");
                closeEntityManager();
              }
          } catch ( Throwable t1)
          { 
            // ut.rollback() operation is missing here !           
            setRunTimeInfo("FATAL ERROR in :  "  + methodName  );
                // Use Throwable as we don't want to loose any important imformation
                // Note: Throwable is super class of Exception class          
            genericException("Error in top level function: " + methodName , (Exception)t1);            
          }
        closeEntityManager();            
        setRunTimeInfo("Leaving " + methodName + " - Entity manager  closed !\n");
        return "index";
      }

 

Reference

Debugging XA Calls in a JPA session running BMT with Netbeans 8.0.2

Overview

BMT calls          JDBC Driver calls 
ut.begin()         oracle.jdbc.xa.client.OracleXAResource   
... 
ut.commit()        oracle.jdbc.xa.client.OracleXAResource.end
                   oracle.jdbc.xa.client.OracleXAResource.commit  <--- Here we want to set a Breakpoint

Prepare the Breakpoint

Class Name           : oracle.jdbc.xa.client.OracleXAResource
Method Name          : commit
Stop on              : Method Entry 
Actions - Suspend    : All Threads
  •  Select suspend all Threads if you want to avoid that any  Wildly Thread is running a rollback
  •  If you want Transaction Recovery takes place by other Wildfly Threads you may select Suspend Breakpoint Thread
  •  Don’t use  oracle.jdbc.xa.OracleXAResource for debugging as this package only defines abstract methods

Start the Netbeans project in DEBUG MODE

Netbeans Debug -> Debug Main Project 
--> Above action will redeploy our project in DEBUG mode

NetBeans: Deploying on WildFly Application Server
    profile mode: false
    debug mode: true
    force redeploy: true
  Undeploying ...
  Initial deploying WFJPA2EL to /usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2EL-1.0.war
  Completed initial distribution of WFJPA2EL
  Deploying /usr/local/wildfly-8.2.0.Final/standalone/deployments/WFJPA2EL-1.0.war
  Application Deployed

Debugger console reports successfully setting the breakpoint in [oracle.jdbc.xa.client.OracleXAResource].commit
  Attaching to localhost:8787
  MethodBreakpoint [oracle.jdbc.xa.client.OracleXAResource].commit successfully submitted.
  User program running

After the program hits a breakpoint runs Debugger Console should report 
Method breakpoint hit in oracle.jdbc.xa.client.OracleXAResource.commit at line 553 by thread default task-3.
Thread default task-3 stopped at OracleXAResource.java:553.

How to Copy the Stack Trace after our Worker Thread stops at a Breakpoint

Select Debugging TAB
  default task-7  [ this Thread was stopped by our Debugger ]
     Hidden Soruce Calls
       OracleXAResource.java:553   <-- Right Click here and select  COPY STACK
Stack Sample 
"default task-7"
oracle.jdbc.xa.client.OracleXAResource.commit(OracleXAResource.java:553)
org.jboss.jca.adapters.jdbc.xa.XAManagedConnection.commit(XAManagedConnection.java:338)
org.jboss.jca.core.tx.jbossts.XAResourceWrapperImpl.commit(XAResourceWrapperImpl.java:107)
com.arjuna.ats.internal.jta.resources.arjunacore.XAResourceRecord.topLevelOnePhaseCommit(XAResourceRecord.java:679)
com.arjuna.ats.arjuna.coordinator.BasicAction.onePhaseCommit(BasicAction.java:2317)
com.arjuna.ats.arjuna.coordinator.BasicAction.End(BasicAction.java:1475)
com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:96)
com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:162)
com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1166)
com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126)
com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:75)
org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:173)
com.hhu.wfjpa2el.JPATestBean.timeoutTest(JPATestBean.java:466)

JPA: Best practice to get and close EntityManagerFactory to avoid Unknown entity bean class error !

Problem Description

After redeploying a WebApplication using JPA you see the following error:

13:02:18.090 Unknown entity bean class: class com.hhu.wfjpa2el.Emp2, 
 please verify that this class has been marked with the @Entity annotation.

13:02:18.091 java.lang.IllegalArgumentException: Unknown entity bean class: class com.hhu.wfjpa2el.Emp2, 
  please verify that this class has been marked with the @Entity annotation.

Solution

  • Restart your WEBServer   or
  • Install a ServletContextListener and close the EMF during contextDestroyed() Event

JAVA Code for implementing a WebListener

package com.hhu.wfjpa2el;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import org.slf4j.LoggerFactory;

@WebListener
public class EMF implements ServletContextListener {

    private static EntityManagerFactory emf;
    final private static String pu = "jpaELPU";
    final static org.slf4j.Logger logger = LoggerFactory.getLogger(ServletContextListenerImpl.class);
    
    @Override
    public void contextInitialized(ServletContextEvent event) {
        logger.info("+++ ServletContextListener : contextInitialized - Inititalizing EMF for PU: " + pu);
        emf = Persistence.createEntityManagerFactory(pu);
        logger.info("+++ ServletContextListener : contextInitialized - Init EMF done for PU: " + pu);
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        logger.info("+++ ServletContextListener : contextDestroyed - Closing EMF for PU: " + pu);
        emf.close();
        logger.info("+++ ServletContextListener : contextDestroyed - Closed EMF done for PU " + pu);
    }

    public static EntityManager createEntityManager() {
        if (emf == null) {
            throw new IllegalStateException("Context is not initialized yet.");
        }
        return emf.createEntityManager();
    }
}

Initialize your Entity Manager by running :  em = EMF.createEntityManager();
Java Code: 
public static EntityManager getEntityManager() 
      {
        EntityManager em = threadLocal.get();
        if (em == null) 
          {
          // setRunTimeInfo(getRunTimeInfo() + Tools.add_hmtl_pre_tag("Creating Entity Manager ! "  ));
            if ( enableLogger )            
                logger.info("Creating Entity Manager Factory ..." );
            em = EMF.createEntityManager();
            threadLocal.set(em);
          }
        return em;
      }

Testing the Code wiht maven deploy/undeploy command

Deploy the WebApplication 
[oracle@wls1 WFJPA2EL]$  mvn wildfly:deploy

Wilfdly Log report:  
13:11:23,170 INFO  [stdout] (MSC service thread 1-4) 13:11:23 [MSC service thread 1-4] INFO  c.h.w.ServletContextListenerImpl - i
                   +++ ServletContextListener : contextInitialized - Init EMF done for PU: jpaELPU
13:11:23,173 INFO  [javax.enterprise.resource.webcontainer.jsf.config] (MSC service thread 1-4) Initializing Mojarra 2.2.8-jbossorg-1 20140822-1131 for context '/WFJPA2EL-1.0'
13:11:23,518 INFO  [org.wildfly.extension.undertow] (MSC service thread 1-4) JBAS017534: Registered web context: /WFJPA2EL-1.0
13:11:24,010 INFO  [org.jboss.as.server] (management-handler-thread - 1) JBAS018559: Deployed "WFJPA2EL-1.0.war" (runtime-name : "WFJPA2EL-1.0.war")

Undeploy the WebApplication 
[oracle@wls1 WFJPA2EL]$   mvn wildfly:undeploy 

Wilfdly Log report:  
13:11:23,170 INFO  [stdout] (MSC service thread 1-4) 13:11:23 [MSC service thread 1-4] INFO  c.h.w.ServletContextListenerImpl - i
                    +++ ServletContextListener : contextInitialized - Init EMF done for PU: jpaELPU
13:11:23,173 INFO  [javax.enterprise.resource.webcontainer.jsf.config] (MSC service thread 1-4) Initializing Mojarra 2.2.8-jbossorg-1 20140822-1131 for context '/WFJPA2EL-1.0'
13:11:23,518 INFO  [org.wildfly.extension.undertow] (MSC service thread 1-4) JBAS017534: Registered web context: /WFJPA2EL-1.0
13:11:24,010 INFO  [org.jboss.as.server] (management-handler-thread - 1) JBAS018559: Deployed "WFJPA2EL-1.0.war" (runtime-name : "WFJPA2EL-1.0.war")
13:13:02,751 INFO  [org.wildfly.extension.undertow] (MSC service thread 1-7) JBAS017535: Unregistered web context: /WFJPA2EL-1.0

 

Reference

JavaScript Features: Ajax and JavaScript Timeout

What is AJAX?

  • AJAX = Asynchronous JavaScript and XML
  • AJAX is a technique for creating fast and dynamic web pages
  • AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes
  • This means that it is possible to update parts of a web page, without reloading the whole page
  • Classic web pages, (which do not use AJAX) must reload the entire page if the content should change
  • Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs
  • AJAX is based on Internet Standards, and uses a combination of:
    • XMLHttpRequest object (to exchange data asynchronously with a server)
    • JavaScript/DOM (to display/interact with the information)
    • CSS (to style the data)
    • XML (often used as the format for transferring data)

Ajax Request used in this sample application

  • Javascript code loadXMLDoc() to trigger an Ajax Request 
function loadXMLDoc()
{
var xmlhttp;
var xmlf=document.getElementById('xmlf').value;
var txt,x,i;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }

/*
 * Only a specific devision named "myDiv" of our HTTP page will be updated 
 */        
document.getElementById("myDiv").innerHTML="Inside loadXMLDOC -> XML File to load: " + xmlf;  

/*
 *  For details using onreadystatechange Event please read :  
 *  http://www.w3schools.com/ajax/ajax_xmlhttprequest_onreadystatechange.asp 
 */
xmlhttp.onreadystatechange=function()
  {     
  if (xmlhttp.readyState === 4 )
     {
        if ( xmlhttp.status === 200)
            {
            xmlDoc=xmlhttp.responseXML;
            txt="";
            x=xmlDoc.getElementsByTagName("ARTIST");
            for (i=0;i<x.length;i++)
                {
                txt=txt + x[i].childNodes[0].nodeValue + "<br>";
                }
            document.getElementById("myDiv").innerHTML=txt;
            }
         else
            {
            document.getElementById("myDiv").innerHTML='Error loading XML file: ' + xmlf + ' HTTP Status Code: ' + xmlhttp.status;            
            }
     }      
  };
xmlhttp.open("GET",xmlf,true);
xmlhttp.send();
}

Function Details:

  • The function loadXMLDoc() starts an asyncronous  Ajax request
  • Parameter xmls points to XM file cd.xml which gets loaded during this request
  • xmlhttp.open(“GET”,xmlf, true) means we use an HTTP GET request to load cd.xml. True means the load request is asyncronous.
  •  xmlhttp.send() actually sends the HTTP request
  •  xmlhttp.onreadystatechange function() gets invoked when HTTP response is ready
  • x=xmlDoc.getElementsByTagName(“ARTIST”) scans the XML document for ARTISTS attribute
  • txt=txt + x[i].childNodes[0].nodeValue + “<br>” adds the artists to our result string
  •  Finally   document.getElementById(“myDiv”).innerHTML=txt updates the only myDiv part of our WEB page
  •  In case of an error [ You may just change cd.xml to cdd.xml  for testing ]
      document.getElementById(“myDiv”).innerHTML=’Error loading XML file: ‘ + xmlf + ‘ HTTP Status Code: ‘ + xmlhttp.status;
      returns some error like:    Error loading XML file: cdd.xml HTTP Status Code: 404
  • For further details you may read following article :

Implementing a Page TimeOut using JavaScript

  • This is quite simple – For details please read function checkdelay() in JavaScript Code published below.
  • JavaScript Code : 
JavaScript Code 
<!DOCTYPE html>
<html>
<head>
<script>
    
function redirect()
{
    window.location="https://google.de";
}

function redirecttohome()
{
    window.location="http://localhost:8180/JavaScriptandAjax-1.0/";
}

function redirectdelay()
{   
   actdelay = delay;
   checkdelay();
}
   
function checkdelay()
{
    /*
     * As long we don't reach the timeout value we need to reschedule checkdelay()
     * every second !
     */
    document.getElementById("myDiv").innerHTML="This page wil be redirected in " + actdelay + " seconds !"; 
    actdelay = actdelay - 1 ;
    if ( actdelay >= 0 )
        setTimeout('checkdelay()', 1000);
    else 
        redirecttohome();
}            


function clean()
{
   document.getElementById("myDiv").innerHTML="";    
}

function loadXMLDoc()
{
var xmlhttp;
var xmlf=document.getElementById('xmlf').value;
var txt,x,i;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }

/*
 * Only a specific devision named "myDiv" of our HTTP page will be updated 
 */        
document.getElementById("myDiv").innerHTML="Inside loadXMLDOC -> XML File to load: " + xmlf;  

/*
 *  For details using onreadystatechange Event please read :  
 *  http://www.w3schools.com/ajax/ajax_xmlhttprequest_onreadystatechange.asp 
 */
xmlhttp.onreadystatechange=function()
  {     
  if (xmlhttp.readyState === 4 )
     {
        if ( xmlhttp.status === 200)
            {
            xmlDoc=xmlhttp.responseXML;
            txt="";
            x=xmlDoc.getElementsByTagName("ARTIST");
            for (i=0;i<x.length;i++)
                {
                txt=txt + x[i].childNodes[0].nodeValue + "<br>";
                }
            document.getElementById("myDiv").innerHTML=txt;
            }
         else
            {
            document.getElementById("myDiv").innerHTML='Error loading XML file: ' + xmlf + ' HTTP Status Code: ' + xmlhttp.status;            
            }
     }      
  };
xmlhttp.open("GET",xmlf,true);
xmlhttp.send();

}
    // global Javascript values 
var delay=10;
var actdeley;
</script>
</head>

<body>

<h2>My CD Collection:</h2>
<input name="XMLFile" type="text" maxlength="16" id="xmlf" value="cd.xml" />
<div id="myDiv"></div>
<button type="button" onclick="loadXMLDoc()">Get my CD collection</button>
<button type="button" onclick="clean()">Clean Display</button>
<button type="button" onclick="redirect()">Page Redirect to Google </button>
<button type="button" onclick="redirectdelay()">Delayed Page Redirect to our Home Page </button>
</body>
</html>

XML File used in this sample : cd.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<CATALOG>
    <CD>
        <TITLE>Empire Burlesque</TITLE>
        <ARTIST>Bob Dylan</ARTIST>
        <COUNTRY>USA</COUNTRY>
        <COMPANY>Columbia</COMPANY>
        <PRICE>10.90</PRICE>
        <YEAR>1985</YEAR>
    </CD>
    <CD>
        <TITLE>Hide your heart</TITLE>
        <ARTIST>Bonnie Tyler</ARTIST>
        <COUNTRY>UK</COUNTRY>
        <COMPANY>CBS Records</COMPANY>
        <PRICE>9.90</PRICE>
        <YEAR>1988</YEAR>
    </CD>
    <CD>
        <TITLE>Greatest Hits</TITLE>
        <ARTIST>Dolly Parton</ARTIST>
        <COUNTRY>USA</COUNTRY>
        <COMPANY>RCA</COMPANY>
        <PRICE>9.90</PRICE>
        <YEAR>1982</YEAR>
    </CD>
</CATALOG>

Reference

Most Info of this POST are just  copied from: