In recent DB2LUW levels a common reason why force application might not work
Biswarup(Bis)Mukherjee 120000HKTY Visits (2072)
Force application is not being able to force certain applications.
This was not uncommon in older levels of Db2.
When a force application is issued against a specific application an interrupt is sent to the specific session code to gracefully terminate the session.
However, there were code areas were the needed interrupt handling were missing.
Over the time the db2 codes have incorporated those interrupt handling which allowed a session to gracefully go away.
However, in the very recent Db2 levels a different kind of force application hanging is being observed.
Over the time the Db2's capability of handling certain kind of traps have been improved.
Db2 have become much better isolating some specific problem thread and suspending it successfully avoiding a full blown Db2 instance crashing situation. The reason of those suspended threads are to be diagnosed and cause to be found out with the help of IBM Db2 Support.
As an end customer many times those suspended threads are not even noticed unless looked into the db2diag.log.
Messages like following could be observed,
Above messages will have associated dump files before that in the db2diag.log
As the end users might not even notice that some of the sessions are in suspended state they try to force related application which will not work as the associated thread is in a suspended state. No logical interrupt will reach to a suspended thread.
Only an instance recycle is needed to cleanup those suspended threads.
So, if a force application does not work then it's suggested to check in the db2diag.log if anything is being suspended or, not.
If anything is suspended most likely it will be a code defect or, effect of any other issues.
So, instead of focusing on why a force application did not work it will be suggested to call the IBM Support and share the details to find the issue.