IO08637: Items are checked out but never get checked in when update item operations and replications are running at the same time

APAR status

• Closed as program error.

Error description

• There is a racing condition when more than one applications
  including CM replicators that try to checkout the same item ID
  at the same time.
  
  There is a time window where one of the application to wait for
  the other application who got the checkout first until commit.
  The problem is compounded if the app who gets the checkout lock
  is in an explicit transaction and deletes a part and/or item
  that the other applicaiton (replicator) is working on and trying
  to checkout the item for. In this case, the item ID may be
  eventually checked out by the replicator, but it can never
  checks in because the part has been deleted.
  

Local fix

• For all applications to immediately commit after a checkout or
  never put check out in a explicit transaction.
  

Problem summary

• When an application performs an update on an item, deletes part
  of the item, and performs checkout in an explicit transaction,
  while the replicator is running, then there is a timing window
  where the item will be checked out by the replicator but does
  not get checked in.
  
  The problem happens because of the racing condition of the
  checkout operation between the application and the replicator.
  
  As a result, your application gets the error "Item already
  checked out" when it is trying to check out or update the item.
  
  In the Resource manager log, there will be an error ICM9798,
  RC=7402, or RC=7405 from the replicator.
  

Problem conclusion

• This problem was fixed in DB2 Content Manager Version 8.3 Fix
  Pack 10. The best practice is to code your application so that
  it never performs a checkout in an explicit transaction. At a
  minimum, you should commit the transaction right after checkout
  to prevent these routines from competing against one another.
  

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

  LIBRARY SERVER

• Fixed component ID

  5724B1907

Applicable component levels