IBM Support

IT20487: MQ Explorer process creates a dump reporting an out of memory error

Subscribe to this APAR

By subscribing, you receive periodic emails alerting you to the status of the APAR, along with a link to the fix after it becomes available. You can track this item individually or track all items by product.

Notify me when this APAR changes.

Notify me when an APAR for this component changes.


APAR status

  • Closed as program error.

Error description

  • The IBM MQ Explorer generates dump files.
    Running a memory analysis tool against these core dumps shows
    the following:
    Possible failure detected in module
    Out of memory detected
     Executable: C:\Program Files\IBM\WebSphere
         52: java/util/Hashtable.rehash ()V(564)
             51: java/util/Hashtable.put

Local fix

Problem summary

  • ****************************************************************
    This issue affects users of
      - IBM MQ Explorer V8.0
      - IBM MQ Explorer V9.0
    Platforms affected:
    Linux on x86, Linux on x86-64, Windows
    The IBM MQ Explorer displays MQ objects in its content view
    tables.  One of the data structures that is used to determine
    what is displayed in each content view table is the grey cell
    Hashtable.  This Hashtable records which cells for each
    individual object shown should be greyed out.
    Cells are greyed out if the property, which would otherwise be
    displayed in that cell, is not applicable to that object.  For
    example, the "Remote queue" property is not valid for a local
    queue, so this cell is greyed out for any local queues displayed
    in the queue content view table.
    Entries are added to this grey cell Hashtable each time a new MQ
    object is created.
    Entries representing each MQ object are also added to this
    Hashtable each time the content view table is redrawn.  Each
    time a redraw event happens the internal table representing the
    objects in the content view table is cleared and regenerated.
    Examples of when this happens include when the table is
    refreshed, when a filter is applied or when moving between types
    of objects.
    However, the grey cell Hashtable was not cleared when the
    internal object table was cleared, and entries were not removed
    when MQ objects were deleted.   This resulted in the Hashtable
    growing over time, eventually leading to an out of memory event
    if the MQ Explorer was left open for sufficient duration.

Problem conclusion

  • The IBM MQ Explorer code has been updated to remove the
    appropriate entry from the grey cell Hashtable when an MQ object
    is deleted.
    It has also been update to clear the contents of the grey cell
    Hashtable each time the internal representation of the list of
    objects in the MQ Explorer table is cleared.
    The fix is targeted for delivery in the following PTFs:
    Version    Maintenance Level
    v9.0 CD    9.0.5
    v9.0 LTS
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'

Temporary fix


APAR Information

  • APAR number


  • Reported component name


  • Reported component ID


  • Reported release


  • Status


  • PE




  • Special Attention

    NoSpecatt / Xsystem

  • 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

  • R800 PSY


[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
31 October 2017