Hi,
I was seeing excessive object lock contention in the JBoss jndi naming
service due to the following call sequence repeating in my application:
"PooledInvokerThread-192.169.1.2: java.util.Hashtable.get :335
PooledInvokerThread-192.169.1.2:
org.jnp.interfaces.NamingContext.useAbsoluteName :1090
PooledInvokerThread-192.169.1.2:
org.jnp.interfaces.NamingContext.getObjectInstance :1123
PooledInvokerThread-192.169.1.2:
org.jnp.interfaces.NamingContext.getObjectInstanceWrapFailure :1142
PooledInvokerThread-192.169.1.2: org.jnp.interfaces.NamingContext.lookup :705
PooledInvokerThread-192.169.1.2: org.jnp.interfaces.NamingContext.lookup :587
PooledInvokerThread-192.169.1.2: javax.naming.InitialContext.lookup :351
PooledInvokerThread-192.169.1.2:
org.hibernate.transaction.JTATransactionFactory.isTransactionInProgress :83
PooledInvokerThread-192.169.1.2:
org.hibernate.jdbc.JDBCContext.isTransactionInProgress :180
PooledInvokerThread-192.169.1.2:
org.hibernate.jdbc.JDBCContext.registerSynchronizationIfPossib :158
PooledInvokerThread-192.169.1.2:
org.hibernate.impl.SessionImpl.checkTransactionSynchStatus :1850
PooledInvokerThread-192.169.1.2: org.hibernate.impl.SessionImpl.getEntityMode
:1274
PooledInvokerThread-192.169.1.2:
org.hibernate.engine.StatefulPersistenceContext.addEntry :415
PooledInvokerThread-192.169.1.2:
org.hibernate.engine.StatefulPersistenceContext.addEntity :382
PooledInvokerThread-192.169.1.2:
org.hibernate.engine.TwoPhaseLoad.addUninitializedEntity :240
PooledInvokerThread-192.169.1.2: org.hibernate.loader.Loader.loadFromResultSet
:1358
PooledInvokerThread-192.169.1.2:
org.hibernate.loader.Loader.instanceNotYetLoaded :1300
PooledInvokerThread-192.169.1.2: org.hibernate.loader.Loader.getRow :1197
..."
My first thought was to improve the AS class org.jnp.interfaces.NamingContext to use a ConcurrentHashMap instead of Hashtable for the JNDI namespace. However, the Sun naming classes are dependent on Hashtable being used. I could copy the ConcurrentHashMap to a new Hashtable when needed but I didn't want to cause even more memory copying to occur in the JNDI name space handling (there is already way too much cloning going on). I started to attempt building a hybrid Hashtable class that is backed by a ConcurrentHashMap but then I received some excellent feedback on the AS dev forum. Adrian suggested caching the UserTransaction object in o.h.t.JTATransactionFactory, although he said that might not work for some applications.
I tried this and it work great for me. Are there any cases where doing the "ut = ( UserTransaction )
context.lookup( utName )" at the time that method "configure(Properties props)" is invoked,
would return a different value than later when "isTransactionInProgress()" is invoked?
I think that getting the UserTransaction early is a good performance enhancement for JTATransactionFactory.
Any disagreement?
I'll Jira this and fix if we agree with the change.
Scott
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