At one stage it was thought that the logging output from child.c was going to be parsed by other programs; that senario never panned out so there's no reason for not having more verbose tracing.
Index: frysk-core/prog/ChangeLog 2006-01-10 Andrew Cagney <cagney@redhat.com> * kill/child.c: Make log messages more verbose; check pthread return codes. (pfatal, fatal, trace, ok, OK): New. (notify_manager): Add trace message parameters. (server): Use throughout. Fix parameter to pthread_join.