The major application is a job management system (Perl), which monitors for events and maintains resource and dependency information. When the everything is in place for a job (file came in to process, another job finished, whatever) then a new job is spawned which runs commands to process the job.

The main monitor logs to this pipe, and when children are forked off they send some initialization data down the pipe to identify themselves and also redirect their stderr stdout to this pipe for logging.

Where sysV streams come in, apparently even though both the parent and children are writing to the same copy of the pipe connection that they got through the fork, somehow the C app is able to figure out which process each incoming line is coming from.