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IC77950: CLI ASYNCHRONOUS EXECUTION MAY CAUSE POOR PERFORMANCE DUE TO 1 SEC DELAY.

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • A CLI based application might intermittently run slow if the
    application enables asynchronous execution. CLI applications can
    enable asynchronous execution by the code like as below:
    
    RC = SQLSetStmtAttr( hstmt,
                         SQL_ATTR_ASYNC_ENABLE,
                        (SQLPOINTER) SQL_ASYNC_ENABLE_ON,
                         0);
    
    The db2trc shows the following 1 sec delay on the application
    thread when the application runs into this performance problem.
    
    40095   1.735732055   SQLExecute entry
    40130   1.735823966   | CLI_asyncRequest entry
    40133   1.735830950   | | sqloAppWaitOnSync entry
    40136   2.730424676   | | sqloAppWaitOnSync data [probe 20:
    WAIT_TIMEOUT]
    40137   2.730431102   | | sqloAppWaitOnSync exit
    

Local fix

  • Users can bypass this issue by disabling asynchronous execution.
    Please implement one of the followings:
    a) Turn SQL_ATTR_ASYNC_ENABLE off in the application code.
    b) Set ASYNCENABLE=0 in db2cli.ini
    c) Set DisableAsyncQueryExecution as 1 in db2dsdriver.cfg.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users who use CLI interface with asynchronous execution.     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * A CLI based application might intermittently run slow if the *
    * application enables asynchronous execution.                  *
    *                                                              *
    * The db2trc shows the following 1 sec delay on the            *
    * application                                                  *
    * thread when the application runs into this performance       *
    * problem.                                                     *
    *                                                              *
    * 40095  1.735732055  SQLExecute entry                         *
    * 40130  1.735823966  | CLI_asyncRequest entry                 *
    * 40133  1.735830950  | | sqloAppWaitOnSync entry              *
    * 40136  2.730424676  | | sqloAppWaitOnSync data [probe 20:    *
    * WAIT_TIMEOUT]                                                *
    * 40137  2.730431102  | | sqloAppWaitOnSync exit               *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Please upgrade to V9.7 FixPack 6 or later, then set          *
    * patch2=112 in db2cli.ini.                                    *
    ****************************************************************
    

Problem conclusion

  • This problem is first fixed in DB2 V9.7 FixPack 6.
    

Temporary fix

  • Users can bypass this issue by disabling asynchronous execution.
    Please implement one of the followings:
    a) Turn SQL_ATTR_ASYNC_ENABLE off in the application code.
    b) Set ASYNCENABLE=0 in db2cli.ini
    c) Set DisableAsyncQueryExecution as 1 in db2dsdriver.cfg.
    

Comments

APAR Information

  • APAR number

    IC77950

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-08-05

  • Closed date

    2012-06-12

  • Last modified date

    2012-06-12

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

    IC77284

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

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC77950

Modified date: 12 June 2012