[jbossts-issues] [JBoss JIRA] (JBTM-2756) Static code analysis: nondeterministic locking behavior at ThreadAssociations#removeAll

[Ondra Chaloupka (JIRA)]

Ondra Chaloupka created JBTM-2756:
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             Summary: Static code analysis: nondeterministic locking behavior at ThreadAssociations#removeAll
                 Key: JBTM-2756
                 URL: https://issues.jboss.org/browse/JBTM-2756
             Project: JBoss Transaction Manager
          Issue Type: Bug
          Components: JTS
    Affects Versions: 5.3.4.Final
            Reporter: Ondra Chaloupka


Static code analysis category: Nondeterministic locking behavior

_CID-17602_: Bad choice of lock object - Nondeterministic locking behavior
in class `ThreadAssociations` [1] at method `removeAll`. There is used synchronized block
where lock is acquired at `globalTxAssociations` and `txAssociations`.

The problem (one for txAssociations is described as)
lock_acquire: Acquiring lock `com.arjuna.ats.jts.extensions.`ThreadAssociations.txAssociations`.
lock_on_assigned_field: Locking on the object referenced by field `ThreadAssociations.txAssociations`. This lock acquisition may race with another thread assigning to this field. The contents of `ThreadAssociations.txAssociations` may change while a thread is inside the critical section, allowing two threads to enter the critical section simultaneously.
 * Instead of using `ThreadAssociations.txAssociations` as a lock, create a final field of type Object which is only used as a lock.
assign_to_field: The expression `ThreadAssociations.txAssociations = null` assigns a new value to `ThreadAssociations.txAssociations`, a field whose contents are used as a lock. The locking behavior of this function may allow this assignment to occur multiple times.


Tom's reaction on this
{quote}
I think that the bug is that there is any synchronization at all on txAssociations because it looks to be indexed by Thread.currentThread().
{quote}


[1] https://github.com/jbosstm/narayana/blob/master/ArjunaJTS/jts/classes/com/arjuna/ats/jts/extensions/ThreadAssociations.java#L125



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