HibernateTransactionManager doesn't clean up when connection not available [SPR-3693]

[spring-projects-issues]

David Hay opened SPR-3693 and commented

If there is a problem opening a connection (e.g. thread pool at capacity and the thread times out waiting for a free database connection), it appears that the HibernateTransactionManager doesn't clean up the SessionHolder object correctly. We diagnosed this by doing the following:

1. Set the database connection pool (Commons DBCP) size to 1 with a 5 second timeout waiting for an available connection
2. Make a request that hits the database and use a debugger to stop that thread (thread 1) while the sole database connection is in use.
3. Make another request that will create (at least) two separate database transactions. (thread 2)
   3a. When the first transaction begins in thread 2, an exception is thrown and caught by HibernateTransactionManager.doBegin(), which throws a CannotCreateTransactionException.
   3b. If the CannotCreateTransactionException is caught by the application and then another transaction is started, HibernateTransactionManager attempts to create a new Session, rather than use the session created by OpenSessionInViewFilter. If the connection is now available, the ConnectionHolder is bound with the data source in a thread local. However, the transaction again fails because of the following:

java.lang.IllegalStateException: Already value [org.springframework.orm.hibernate3.SessionHolder@78d8ac] for key [org.hibernate.impl.SessionFactoryImpl@1ccf137] bound to thread [http-8080-Processor2]

This leaves the ConnectionHolder bound to the thread local after the request finishes.

Now, any future requests on that thread fail with the following exception because the ConnectionHolder is still bound to the thread local:

org.springframework.transaction.IllegalTransactionStateException: Pre-bound JDBC Connection found! HibernateTransactionManager does not support running within DataSourceTransactionManager if told to manage the DataSource itself. It is recommended to use a single HibernateTransactionManager for all transactions on a single DataSource, no matter whether Hibernate or JDBC access.

---

Affects: 2.0.5, 2.0.6, 2.1 M1, 2.1 M2

Issue Links:

• Database connection problems cause Spring to raise an IllegalStateException and resulting in transaction state not being cleaned up [SPR-5133] #9806 Database connection problems cause Spring to raise an IllegalStateException and resulting in transaction state not being cleaned up

[spring-projects-issues]

David Hay commented

The following patch seems to fix the problem. This keeps a new Session from getting created in the second transaction on thread 2 and the transaction fails quickly with a session closed error.

--- /localtmp/home/javalibs/spring-framework-2.0.5/src/org/springframework/orm/hibernate3/HibernateTransactionManager.java 2007-03-18 12:56:16.000000000 -0600
+++ src/main/java/org/springframework/orm/hibernate3/TestHibernateTransactionManager.java 2007-07-17 16:24:25.000000000 -0600
@@ -535,6 +533,7 @@

catch (Exception ex) {
        SessionFactoryUtils.closeSession(session);

       txObject.getSessionHolder().setSynchronizedWithTransaction(false);
                  throw new CannotCreateTransactionException("Could not open Hibernate Session for transaction", ex);
          }
  }

[spring-projects-issues]

Juergen Hoeller commented

Indeed, this may run into invalid state in case of a pre-bound Session, the Connection not having been obtained yet and no Connection being available anymore...

I've fixed this for 2.1 M3 and 2.0.7; should be available in the next nightly snapshots (http://static.springframework.org/downloads/nightly/snapshot-download.php?project=SPR).

Juergen

[spring-projects-issues]

David Hay commented

Thanks for the quick turnaround!

Thinking on this some more...is closing the session when failing to open a transaction (e.g. because a connection is unavailable) really the right thing to do? If a connection becomes available later on in the request, it would be nice for the application to be able to execute an additional transaction without having to clean up the pre-bound session itself.

[spring-projects-issues]

Juergen Hoeller commented

You're right. Fortunately, I've already addressed that in my earlier commit: In case of an exception, HibernateTransactionManager only closes the Session in case of a new Session now; i.e. it leaves a pre-bound Session (such as one from OpenSessionInViewFilter) open. So should already find the correct behavior there in tonight's snapshots.

Juergen

[spring-projects-issues]

David Hay commented

Great...I saw the check for the new session in the latest CVS code, though I don't see anything addressing the SessionHolder transaction synchronization flag. I'll look for your changes in tonight's nightly build.

[spring-projects-issues]

Juergen Hoeller commented

The "synchronizedWithTransaction" flag is now set as late as possible, after binding the SessionHolder to the thread. Hence we don't need to reset it in the catch block, since it will only be set if everything else has succeeded already. (Previously it was set at the beginning of the process, where various things might still fail.)

BTW, I've applied similar changes to JpaTransactionManager and JdoTransactionManager, to be on the safe side there as well.

Juergen