DB2 FOR LUW / DB2FORLUW / 970 - DB2

In a Federated environment that utilizes two-phase commits, the 
instance can hang with a LOCK snapshot waiting on a tranEntry 
latch. The lock snapshot's callstack looks like this: 
sqlpm_write_appl_locks 
sqm_snap_appl_locks 
sqm_snap_db_locks 
sqlmonssagnt 
sqlmonssbackend 
sqlesrvr 
 
The lock snapshot is waiting for the tranEntry latch and holding 
the dblatch, m_appServLatch and masterAppLatch. 
 
At the same time a federated server has been defined to use 
two-phase commit and a federated agent is attempting to 
establish an XA transaction by calling sqlqg_FMP_FedStart. The 
agent's stack looks like this: 
msgrcv 
sqlorqueInternal 
sqlorque2 
sqloTQMRequestMLN 
sqlccipcconnr 
sqlccconnr 
sqljcCommConnect 
sqljcCmnMgrInit 
sqljrCreateTransport 
sqljrAssociateTransport 
sqljrInternalConnect 
sqljrFindBestAddressAndConnect 
sqljrDrdaArAuthenticate 
sqlexAppAuthenticate 
sqljrDrdaArConnect 
sqleUCdrdaARinit 
sqleUCappConnect 
sqlxaConnect 
DRDA_Connection::xa_open 
FencedServer::connect 
FencedServer::connect_current_user 
sqlqgConnect 
sqlqg_FMP_FedStart <------------------- 
sqlqgRouter 
sqlqg_fedstp_hook 
sqlqgDyload 
sqlriFedInvokerTrusted 
sqlriFedInvokeInvoker 
sqlqg_Call_FMP_Thread 
sqlqgFedStart 
sqlqgOpen 
sqlri_djx_rta 
sqlriNljnPiped 
sqlriSectInvoke 
sqlrr_process_execute_request 
sqlrr_execute 
sqljs_ddm_excsqlstt 
sqljsParseRdbAccessed 
sqljsParse 
sqljsSqlam 
: 
 
The Federated agent is holding the tranEntry latch when it calls 
sqlqgConnect to establish the XA connection and is waiting for 
an agent to be provided by the IPC connection manager. 
 
 
The IPC connection manager is hung waiting for the 
m_appServerLatch being held by the snapshot agent. 
SQLO_SLATCH_CAS::getConflictComplex 
SQLO_SLATCH_CAS::getConflict 
sqlo_latch 
sqeAppServices::CreateAppl 
sqeAgentServices::RequestAgent 
sqlccipcconnmgr_child 
sqloEDUEntry

**************************************************************** 
* USERS AFFECTED:                                              * 
* Anybody using federated transaction two phase commit         * 
* transaction and LOCK snapshots                               * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to Version 9.7 Fix Pack 6                            * 
****************************************************************

This hang can be avoided if the federated transaction does not 
require two phase commit. Two phase commit can be disabled as 
follows: 
 
alter server <server name> options (set DB2_TWO_PHASE_COMMIT 
'N')

DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
 

Problem was first fixed in Version 9.7 Fix Pack 6

not known / see Local fix

forerunner  : APAR is sysrouted TO one or more of the following: IC83256 IC96023 
follow-up : 

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

25.01.2012
09.05.2012
09.05.2012

9.7.FP6