Hot off the presses is an urgent update for anybody on R12 or planning on going to R12. Today we encountered an issue where our users reported their concurrent requests were ending in Error, and in the log file was "emsg:was terminated by signal 25" but we didn't know of anything wrong or why this would be happening. My co-worker searched on MOS and found note 842850.1 which is directly on point indicating that once the reports.log file in $APPLCSF/$APPLLOG or $INST_TOP (ours was in $FND_TOP) grows to be 2GB concurrent processing stops. All reports, no matter how many nodes you have if it's all on a shared directory structure, come to a complete dead stop.
Luckily we didn't have any critical business processes die because of this, but you need to take steps immediately to make sure you don't encounter this same situation which could happen while reports are being run that could cause orphan records or incomplete data to be left in your system. Our DBA was able to follow the action listed in the note without taking the Concurrent Manager down, so I don't know if that will cause a part 2 for this document or not, but I'll keep you updated if we encounter any issues because of that.
What is also interesting about this, is that our DBAs did encounter this is problem in QA during their building and maintenance of R12 and applied patch 10152652 which is notated as fixing this issue when we went to PROD but it did not work for us today. That is probably why the note was updated within the last week. :}