Preview Service is Not Working

Question

When i Update my DD4T Web Application Content , and click on Update Preview button then it doesn't work, i don't see Updated Content and Update Preview pop up blinks again and again. So my Preview Service is not Working at all.

However if i click on finish editing for my changes then after 2-3 minutes my Update Preview works, i don't get any popup blinking.Everything works fine.

My Findings are : When i Finish Editing, Preview Web Service sending items to the Preview Database as i can see Component and Component Presentations are in Preview Database, then it Update Items in to Broker Database, and Publishes the Page.Publishing is getting Success but i can still see Component and Component Presentation entries are in Preview Database, that is why i am getting Update Preview blinks again and again. Once (after 1-2 minutes) Items gets Deleted from Preview Database i can see the updated Content in XPM and also Update Preview doesn't blink anymore.

I Disabled CacheSettings but still it's not working, also in my Preview Service Logs i found these Errors :

2016-02-04 06:29:26,778 ERROR SessionWrapperFactory - Exception while cleaning-up session data
com.tridion.broker.StorageException: javax.persistence.RollbackException: Error while committing the transaction
at com.tridion.storage.persistence.JPABaseDAO.remove(JPABaseDAO.java:157) ~[cd_datalayer.jar:na]
at com.tridion.storage.persistence.JPAItemDAO.remove(JPAItemDAO.java:246) ~[cd_datalayer.jar:na]
at com.tridion.storage.persistence.session.SessionWrapperFactory.deleteItemMeta(SessionWrapperFactory.java:184) ~[cd_session.jar:na]
at com.tridion.storage.persistence.session.SessionWrapperFactory.cleanupSessionData(SessionWrapperFactory.java:160) ~[cd_session.jar:na]
at com.tridion.storage.session.SessionManagerImpl.expireSession(SessionManagerImpl.java:414) [cd_session.jar:na]
at com.tridion.storage.session.SessionManagerImpl.performCleanup(SessionManagerImpl.java:230) [cd_session.jar:na]
at com.tridion.storage.persistence.session.SessionsCleanerMonitor.run(SessionsCleanerMonitor.java:52) [cd_session.jar:na]
at java.lang.Thread.run(Unknown Source) [na:1.7.0_71]

           Caused by: javax.persistence.RollbackException: Error while committing the transaction
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:90) ~[hibernate-entitymanager.jar:4.0.1.Final]
at com.tridion.storage.persistence.JPABaseDAO.remove(JPABaseDAO.java:148) ~[cd_datalayer.jar:na]
... 7 common frames omitted
                   Caused by: javax.persistence.OptimisticLockException: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.tridion.storage.PageMeta#com.tridion.storage.ItemMetaPK@2441b]
at org.hibernate.ejb.AbstractEntityManagerImpl.wrapStaleStateException(AbstractEntityManagerImpl.java:1394) ~[hibernate-entitymanager.jar:4.0.1.Final]
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1308) ~[hibernate-entitymanager.jar:4.0.1.Final]
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1289) ~[hibernate-entitymanager.jar:4.0.1.Final]
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:78) ~[hibernate-entitymanager.jar:4.0.1.Final]
... 8 common frames omitted
  Caused by: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.tridion.storage.PageMeta#com.tridion.storage.ItemMetaPK@2441b]
at org.hibernate.persister.entity.AbstractEntityPersister.check(AbstractEntityPersister.java:2359) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3127) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3327) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.action.internal.EntityDeleteAction.execute(EntityDeleteAction.java:91) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:272) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:264) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:191) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:326) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1081) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:315) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175) ~[hibernate-core.jar:4.0.1.Final]
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:73) ~[hibernate-entitymanager.jar:4.0.1.Final]
... 8 common frames omitted                                                                                         

Answer 1

It is good to realise that the exception you are seeing is actually not critical and not the cause of preview not working. This exception happens when multiple preview processes are trying to cleanup your content in the preview store. Eventually the cleanup will succeed, in later versions of the product we have modified this message to be less 'critical looking'.

Can you also please try to re-create your preview database with the powershell scripts, it could be that a simple wipe of the DB could do the trick.

Otherwise some more logging in debug log format are needed.