You may find that requests are stacking up in the concurrent managers with a status of "pending". This can be caused by any of these conditions:
1. The concurrent managers were brought down will a request was running.
2. The database was shutdown before shutting down the concurrent managers.
3. There is a shortage of RAM memory or CPU resources.
When you get a backlog of pending requests, you can first allocate more processes to the manager that is having the problem in order to allow most of the requests to process, and then make a list of the requests that will not complete so they can be resubmitted, and cancel them.
To allocate more processes to a manager, log in as a user with the System Administrator responsibility. Navigate to Concurrent -> Manager -> Define. Increase the number in the Processes column. Also, you may not need all the concurrent managers that Oracle supplies with an Oracle Applications install, so you can save resources by identifying the unneeded managers and disabling them.
However, you can still have problems. If the request remains in a phase of RUNNING and a status of TERMINATING after allocating more processes to the manager, then shutdown the concurrent managers, kill any processes from the operating system that won't terminate, and execute the following sqlplus statement as the APPLSYS user to reset the managers in the FND_CONCURRENT_REQUESTS table:
update fnd_concurrent_requests
set status_code='X', phase_code='C'
where status_code='T';
