PM26010: WTRN0006W DUE TO TRANSACTION TIMEOUT OCCURS USING TIGHTLY COUPLED TXS WITH DB2 DUE TO LOCK TIMEOUT; CAN'T SET TMLCS

Fixes are available

APAR status

Closed as new function.

Error description

IBM DB2 added a feature to set accept an XA flag on an
xa.start() operation to specify that the tx should be loosely
coupled.  This was added with the DB2 APAR PK78198 which
was released in their driver, JCC 3.6.93.  The APAR which
introduced this flag is DB2 z/OS V8 APAR PK47713.  The APAR
PK78198 is a full driver which contains this APAR.
http://www-01.ibm.com/support/docview.wss?uid=isg1PK78198
.
   The reason for this flag is to prevent a LOCK timeout
that can occur with tightly-coupled transactions.
A tightly-coupled transaction occurs in a scenario like this:
   two EJB method calls are made in the same transaction
that access the same DB2 db on Z/OS. The transactions are queued
but the second goes in timeout.
.
   The exception that is thrown with the Type-4 XA Connectivity
Driver is an SQLException that has an SQLCODE911 (-911); this is
thrown when two different WAS servers/JVMs each running under
the same global transaction using the same  database on z/OS
tries to update the same row in a table.  This results in a
deadlock condition, causing the transaction to rollback.
.
   DB2 introduced a new XA flag, TMLCS (Loosely Coupled), which
can be used to enable sharing of locks on the DB2 for XA
branches that have same global transaction ID but different
branch qualifier.  The flag is documented here.
public class DB2XAResource
{
   public static final int TMLCS = 8388606; // 0x00800000
}
.
   The new XA flag TMLCS can be passed as one of the valid

flags to javax.transaction.xa.start() API.

public class DB2XAResource
{
   public static final int TMLCS = 8388606; // 0x00800000
}
.
   When DB2 is used with WebSphere Application Server and the
J2EE application uses a tightly-coupled tx, the way this is
manifested is with a transaction timeout.
[21/07/10 9.50.55:184 CEST] 00000005 TimeoutManage
I   WTRN0006W: Transaction
EJBTwoObjectsEAR#EJBTwoObjects.jar

[21/07/10 9.50.55:186 CEST] 00000005 TimeoutManage I
 WTRN0124I: When the timeout occurred the thread with which the
transaction is, or was most recently, associated was Thread
[WebContainer : 2,5,main]. The stack trace of this thread
when the timeout occurred was:
 com.ibm.db2.jcc.uw.UWReply.recvBuff(Native Method)
 com.ibm.db2.jcc.uw.UWReply.b(UWReply.java:75)
 com.ibm.db2.jcc.t4.cb.c(cb.java:249)
 com.ibm.db2.jcc.t4.cb.c(cb.java:360)
.
   The DB2 feature cannot be readily used by WebSphere
Application Server.  One may try to manage one's own transaction
using a UserTransaction fora servlet or using Bean Managed
Transactions, and try to pass the xa flag indicated.  But this
is not always possible.  And the API changed is not intended for
use with user-developed applications.
.
   What is needed is a way to set this parameter from the
Application Server via a data source custom property or java
property.

Local fix

One may try to use a UserTransaction or BMT EJB to have the
control of the xa.start command to try to set this flag.

Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server V6.1 and V7.0 who use DB2.           *
****************************************************************
* PROBLEM DESCRIPTION: By Default DB2 supports Loosely         *
*                      coupled Transactions and Transaction    *
*                      branches does not share locks, causing  *
*                      deadlocks.                              *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
There was  no property to support Loosely coupled
Transactions to Share locks on DB2.

Problem conclusion

Added code to support the Looselycoupled transactions in Db2
to Share Locks.
The custom property  transactionBranchesLooselyCoupled=false
should be set on DataSource.
From the administrative console you can set the custom property
in the following path :
JDBC providers -> <Driver Provider name> -> Data sources >
<DataSource name> -> Custom properties

The fix for this APAR is currently targeted for inclusion in
fix packs 6.1.0.39 and 7.1.1.17.  Please refer to the
Recommended Updates page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PM26010
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2010-11-05
Closed date
2011-05-03
Last modified date
2011-05-03

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WEBS APP SERV N
Fixed component ID
5724H8800

Applicable component levels

R61A PSY
UP
R61H PSY
UP
R61S PSY
UP
R61W PSY
UP
R700 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
27 October 2021

Tips

PM26010: WTRN0006W DUE TO TRANSACTION TIMEOUT OCCURS USING TIGHTLY COUPLED TXS WITH DB2 DUE TO LOCK TIMEOUT; CAN'T SET TMLCS

Fixes are available

Subscribe

APAR status

Closed as new function.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R61A PSY

R61H PSY

R61S PSY

R61W PSY

R700 PSY

Document Information

Share your feedback

Need support?