IT44419: MQ Appliance might reload due to memory throttling.

APAR status

• Closed as program error.

Error description

• The IBM MQ Appliance might undergo a reload triggered by memory
  throttling, even when there is available free memory remaining.
  
  
  Prior to the reload, the subsequent messages are generated in
  the default log.
  20230711T040556.139Z [0x804000a3][system][critic]
  throttle(Throttler): tid(2063): Free memory very low
  (19.924494). Throttling.
  20230711T040556.139Z [0x01a40001][system][warn]
  throttle(Throttler): tid(2063): Throttling connections due to
  low memory
  20230711T040556.278Z [0x804000a0][system][notice]
  throttle(Throttler): tid(23871): Not permitting
  connection.Reason(throttling state) : Low Memory.
  20230711T040602.034Z [0x804000a2][system][notice]
  throttle(Throttler): tid(2063): Memory now available
  -re-enabling connections
  20230711T040602.034Z [0x01a50004][system][notice]
  throttle(Throttler): tid(2063): Memory usage recovered above
  threshold
  
  The backtrace file generated during the reload captures the
  following information:
  
  Throttler forced system reload. Reason : Low Memory.Tue Jul 11
  07:41:39 DST 2023
  Build 347945mq on 2022/12/22 11:27:25
  DPOS running 1.1, installed 1.1
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  MQ Appliance 9.3 users are affected.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A logic error when calculating the amount of memory in use meant
  that a low memory condition could be triggered prematurely
  resulting in an appliance reload.
  

Problem conclusion

• The firmware has been updated to ensure the out of memory
  condition is calculated correctly
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.3 LTS   9.3.0.15
  v9.x CD    9.3.5
  
  The latest available maintenance can be obtained from
  'IBM MQ Recommended Fixes'
  https://www.ibm.com/support/pages/recommended-fixes-ibm-mq
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'IBM MQ
  Planned Maintenance Release Dates'
  https://www.ibm.com/support/pages/ibm-mq-planned-maintenance-rel
  
  ---------------------------------------------------------------
  

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

  MQ APPLIANCE M2

• Fixed component ID

  5900ALJ00

Applicable component levels