"gdb" (gdb 6.3) knows about threads but core dumps half the time and is 10 years old.
"egdb" (gdb 7.6) does not work right with multithreaded programs. It sees only one thread. Neither supports "set scheduler-locking". Is there any good option for debugging a multithreaded program? I'm running OpenBSD 5.4 on amd64. What's the right mailing list for this, if not tech?