[hibernate-issues] [Hibernate-JIRA] Created: (EJB-351) Optimistic Locking Deadlocks with Application Manged EM in Threaded Environment

[Allen Harvey (JIRA)]

Optimistic Locking Deadlocks with Application Manged EM in Threaded Environment
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                 Key: EJB-351
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/EJB-351
             Project: Hibernate Entity Manager
          Issue Type: Bug
          Components: EntityManager
    Affects Versions: 3.3.2.GA
         Environment: Annotations 3.3.1.GA
Core 3.2
Windows XP Pro
Netbeans 6.01
Sun JDK 1.6.04
MSSQL 2000
            Reporter: Allen Harvey
         Attachments: hibernateJPAtest.zip

I have posted about this issue in the forums here: http://forum.hibernate.org/viewtopic.php?t=985460, but have received no reply. I am hoping it is a bug, and not a mistake on my part.

When using an application managed entity manager in a concurrent environment, the database is deadlocking. The scenario is this:

Create several bank accounts
Persist them
Create many (10) clients
Clients simultaneously transfer money randomly among the accounts as fast as possible
Each transfer between two accounts is a transaction

Optimistic lock exceptions are expected and handled (a new em is created and the transaction retried).

Depsite having annotated the account entity  (@Version),  settings ordered updates, using a thread-local entity manager, and setting the MS SQL 2000 db to read committed, the database deadlocks.

I have created a small sample application that reproduces the problem, it is attached. Finally, I tried this on Mysql 5.x as well, and that database also deadlocked, so it doesn't appear to be a database driver issue. 

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