Jörn Gersdorf created ARIES-1265:
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Summary: Aries Transactions: Transaction Enlisting failing for
multiple OracleXADataSources/Connections
Key: ARIES-1265
URL: https://issues.apache.org/jira/browse/ARIES-1265
Project: Aries
Issue Type: Bug
Components: Transaction
Environment: JBoss Fuse 6.1, Apache Karaf 2.3.0, Aries Transaction
1.0.x, Oracle 11.2
Reporter: Jörn Gersdorf
When using multiple Oracle XADataSources (and thus XAConnections) within the
same global XA transaction, Apache Aries/Geronimo fails with ORA-24798 (Cannot
resume distributed transaction branch on another instance). Don´t be fooled by
the "on another instance": actually I`m connecting to the same Oracle instance
(which is not behind a RAC).
h3. Scenarios
I tested three scenarios, always using two DataSources within one global XA
transaction:
1. Use two DataSources, each with same user principal
2. Use two DataSources, each with same user principal
3. Use one DataSource
In all three scenarios I do the following:
1. txManager.begin()
2. con1 := Get connection from DataSource1
3. SELECT * from DUAL@con1
4. con2 := Get connection from DataSource2
5. SELECT * from DUAL@con2
6. txManager.begin()
Scenario (two different DataSources) 1 and 2 fail with ORA-24798. Scenario 3
(one DataSource for both connections) does not fail, but this is only due to
{{org.apache.aries.transaction.jdbc.internal.XADatasourceEnlistingWrapper}}
caching connections per (DataSource, Transaction) pair: as a result con1 ==
con2 in this scenario.
h3. Problem description
The root cause is how {{javax.transaction.XAResource#isSameRM(XAResource)}} is
used in
{{org.apache.geronimo.transaction.manager.TransactionImpl#enlistResource(XAResource)}}.
If there is already an {{XAResource}} enlisted in the current transaction
running on the same RM as the {{XAResource}} to be enlisted (according to
{{isSameRM}}) then Aries/Geronimo tries to {{TMJOIN}} the branch.
Now, this is exactly the point where Oracle fails with {{ORA-24798}}.
Frankie Viet has an excellent discussion about the whole issue at
http://frankkieviet.blogspot.com/2010/01/how-to-enlist-and-delist-xa-resources.html.
In summary it says that the sequence
{noformat}
1: // MULTIPLE ACTIVE
2: r1.start(xid, TMNOFLAGS);
3: r1.isSameRM(r2); // returns true
4: r2.start(xid, TMJOIN);
5: r2.end(xid, TMSUCCESS);
6: r1.end(xid, TMSUCCESS);
7: r1.commit(xid, true);
{noformat}
is neither working on Oracle not Websphere MQ (and other commercial systems).
Instead that link suggests the following sequence working in most cases:
{noformat}
1: // SINGLE ACTIVE 2
2: r1.start(xid, TMNOFLAGS);
3: r1.isSameRM(r2); // should return true
4: ... // use r1
5: r1.end(xid, TMSUCCESS);
6: r2.start(xid, TMJOIN);
7: ... // use r2
8: r2.end(xid, TMSUCCESS);
9: r1.start(xid, TMJOIN);
10: ... // use r1 again
11: r1.end(xid, TMSUCESS);
12: r1.commit(xid, true);
{noformat}
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