IT12508: IPL THROTTLING ON SYSTEMS WITH LARGE LOGICAL LOG SPACE CAN SEE THE IPL THREAD YIELD FOR LONG PERIODS OF TIME

APAR status

• Closed as program error.

Error description

• The IPL thread breaks down an index copy into bite sized pieces
  of work to avoid the transfer turning into a long transaction.
  At the commit phase of each of these sub transactions, a check
  is made to make sure the IPL thread is not flooding the logical
  logs, and prematurely forcing other unrelated transactions into
  a long transaction state. To do this, a check is made to see
  whether the instance has advanced LTXHWM * 0.5 beyond the oldest
  transaction, and if it has, the IPL thread will go into a wait
  state (mt_yield) in ipl_commit.
  
  Example stack of IPL thread waiting for other transactions to
  catch up:
  
    Stack for thread: 33527735 ipl
     base: 0x07000001cff08000
      len:   69632
       pc: 0x00000001000620f0
      tos: 0x07000001cff18740
    state: sleeping
       vp: 9
  
    (oninit)yield_processor_mvp
    (oninit)mt_yield
    (oninit)ipl_commit
    (oninit)ipl_traverseidx
    (oninit)ipl_logidxpgs
    (oninit)ipl_logidxpgs_fd
    (oninit)ipl_logidxpgs_partn
    (oninit)ipl_startup
    (oninit)th_init_initgls
    (oninit)startup
  
  Problems can occur if you have sessions which start a
  transaction, and then become idle, which means the IPL thread
  can become blocked until those sessions are either terminated by
  the client or hit the LTXHWM and are rolled back by the engine.
  If the instance is configured with a large amount of logical log
  space, the IPL thread can become blocked for a long time.
  

Local fix

• To allow the IPL thread to continue, you might consider finding
  those sessions and forcing a commit or rollback, or terminate
  them with an 'onmode -z'.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users enabling Index Page Logging                            *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IBM Informix Server 11.70.xC9                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IBM Informix Server 11.70.xC9
  

Temporary fix

Comments

APAR Information

• 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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels

• RB70 PSY

     UP