IJ09070: WEBCONTAINER BLOCKS THREADS FROM GETTING NEXT SEQUENCE NUMBER DURING AN INSERT WHEN USING SQL SERVER

APAR status

• Closed as program error.

Error description

• A webcontainer is blocking threads from getting the next
  sequence number on an insert statement when using SQL Server.
  This causes the database to hang and prevent users from using
  and logging in to Maximo.
  
  PROBLEM:
  Maximo becomes unusable and must be restarted.
  
  PERFORMANCE ISSUE:
  N/A
  
  STEPS TO REPRODUCE:
  1) Log in as user Wilson.
  
  2) Create a "Quick Insert" link for Quick Reporting on the
  start center (if it's already not there).
  
  3) You will need to somehow simulate a long running query on
  one of the portlets on the start center. I used my eclipse
  debugger to step into the SQS JDBC driver code and pause it as
  soon as the lock was obtained on the connection.
  
  4) While the portlet is spinning and "waiting" for the database
  to return the result set, click on the Quick Insert link for
  Quick Reporting. At this point instead of taking you to the
  Quick Reporting App (Insert) you will see a spinning icon.
  Basically at this point the Quick Insert is waiting for the
  portlet query to release the lock. This is normal and expected.
  
  What's not normal is the following ...
  
  5) Open up a different browser (IE or Firefox), basically
  anything but the browser you used in the the steps 1 - 4 above.
  This is to simulate other users logging into the startcenter
  while the Quick Insert in step 4, from user Wilson is blocking
  other users from getting the next sequence number.
  
  6) Login as a different user like Maxadmin.
  
  7) Instead of taking you to the start center you will see a
  blank page with a spinning icon. Basically any user logging
  into the system is blocked.
  
  CURRENT ERRONEOUS RESULT:
  Insert blocks threads from getting sequence numbers preventing
  other users from logging in.
  
  EXPECTED RESULT:
  One user's session to not interfere with another users sessions
  and not have sequence numbers blocked.
  
  ADDITIONAL INFO:
  1) We were able to analyse and reproduce this issue based on
  thread dumps from August 13/14.
  
  2) This issue happens only when there is is a long running
  query on a startcenter portlet and the same user is also trying
  to insert while waiting for the query to finish.
  
  3) If the long running query issue is resolved since Aug 13/14
  then this fix may not impact them right away. However it's
  probably a good idea to take the fix.
  
  ENVIRONMENT (SYSTEM INFO):
  Maximo 7.6.0.9 IFIX05
  
  LOCAL FIX:
  N/A
  

Local fix

• Prevent inserts during long running queries to reduce amount of
  long running queries.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users on SQL Server databases.                               *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * On Maximo environments using SQL Server databases, if        *
  * mxe.maxsequencecheck is set to 1, threads may be blocked     *
  * from getting the next sequence number while checking for     *
  * uniqueness.                                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  

Problem conclusion

• The fix for this APAR is included in the following package:
                          | Release 7.6.1.1 of Base Services.
  

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

  MAXIMO SYSTEMS

• Fixed component ID

  5724R46AV

Applicable component levels

• R760 PSY

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