[jbossseam-issues] [JBoss JIRA] Created: (JBSEAM-2893) Thread-safety issues on Websphere with EM-injected components

[Eric Jung (JIRA)]

Thread-safety issues on Websphere with EM-injected components
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                 Key: JBSEAM-2893
                 URL: http://jira.jboss.com/jira/browse/JBSEAM-2893
             Project: Seam
          Issue Type: Bug
         Environment: Websphere 6.1.0.13 with EJB Feature Pack on both  Windows XP SP2 and Solaris 9 (SunOS 5.9)
            Reporter: Eric Jung


I'm attaching an extremely simple application that demonstrates thread-safety issues with EntityManager / EntityManagerFactory in Websphere 6.1. This application has one entity bean, one session bean, and one web page. 

The problem is very easy to reproduce. Just start typing "e" in the search field, which uses rich:suggestionbox, and very quickly press the search button. This results in two queries being performed simultaneously--one from the rich:suggestionbox keypress, and one from submitting the page's form. All 1000 rows of data begin with "e" so the query is slow, making it easier to create queries that execute simultaneously.

You'll get one of the following exceptions if you time things right (this isn't difficult, just hit the search button very quickly--if you're too slow, both queries will succeed without error):

"javax.ejb.ConcurrentAccessException: TX_METHOD_READY: wrong transaction"
or
"java.lang.IllegalStateException: could not acquire lock on @Synchronized component: memberSearch"

I've tried this EAR with both Hibernate and OpenJPA as persistence providers, and switched databases between Apache Derby and DB2. In all four permutations, I get the exact same exceptions. That should rule out any JDBC driver or JPA implementation issues.

I suspect this problem is related to the issue mentioned in this blog post by Sahoo (a Sun engineer): http://weblogs.java.net/blog/ss141213/archive/2005/12/dont_use_persis_1.html. Unfortunately, WebSphere doesn't support servlets 2.5 so <persistence-context-ref/> isn't available in web.xml. I tried the approach he discusses in "Application Managed Entity Manager", but it hasn't yet worked.

You can download a pre-built EAR (with source code included) at http://www.mediafire.com/?tlxxgaj4qtm, but I'll be attaching source code and configuration files here, too (can't attach the EAR directly since it's 11.6 MB with all the required JARs).

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