Andrew Dinn commented on JBTM-352:
Well spotted. Unfortunately, this is probably not a valid fix. Essentially you are using
the Uid as a key for entries in map _timeouts and this is inadequate for the general
The reason for using Reapable objects as the key is that it allows the comparison to be
defined by the Reapable -- this is possible because when Hashmap does a get or put with
key 'k' it compares against existing entries using k.equals(entry.key). So, any
Reapable can implement 'equals' to ensure that it compares correctly against other
Reapables. If we switch to keying using Uids then this test will by bypassed. Your
'fix' may work with your test but it may break other cases.
This feature is used when inserting and removing ControlWrapper objects. If the argument
is a ControlWrapper the equals method checks whether both ControlWrappers are local. If so
it checks whether their ControlImple fields are 'equal'. If either ControlWrapper
is non-local then it has to invoke is_same_transaction on the associated Coordinators.
The equals method in ControlWrapper also contains a check for the case that the argument
is a Uid. If so it compares the supplied Uid argument to the wrapper's Uid. This is
intended to catch the case where a Uid is supplied as argument to
TransactionReaper.remove(). The reason this is failing is because the comparison is being
done the wrong way round i.e. by calling Uid.equals(ControllWrapper) rather than
This looks to me like a failed attempt to optimize the remove operation. A correct but,
possibly, slow implementation might be to change all calls to remove which supply a Uid
and instead supply a ControlWrapper constructed using a Control available where the call
is made. I will look for a better option before attempting to implement this fix.
By the way, I only found two places where a non-Reapable is supplied, both in
OTSManager.destroyControl. In one case the argument is a Uid, in the other a Control! I am
not yet sure if the second case is correct or an error.
Memory leak in TransactionReaper._timeouts
Project: JBoss Transaction Manager
Issue Type: Bug
Security Level: Public(Everyone can see)
Components: Transaction Core
Affects Versions: 4.3.0.GA
Environment: Compiled 4.3.0.GA for the EAP 4.3 as JTS according to the
instructions (by setting JBOSS_HOME to jboss-5.0.0.Beta4) on RHEL4.
Run ~ 1500 JMS transactions in EAP 4.3 all configuration on RHEL4 to see it leaks.
Used Sun jdk 22.214.171.124
Reporter: Ivan Szanto
Assigned To: Andrew Dinn
Fix For: 4.4.CR1
The leak can also be seen by using the debugger to check the number of entries in
TransactionReaper._timeouts after a couple of transactions.
It appears that the TransactionReaper.insert method uses ControlWrapper objects as keys
when putting elements into the hashtable, but the TransactionReaper.remove method
sometimes unsuccessfully tries to use Uid ojbects to remove them.
I will post a corrected version of TransactionReaper.java.
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