Nice bug

[Glenn Shapland]

I have an X application which starts up like a daemon
using the following code.

    /* prevent reacquisition of a controlling terminal */
    if (fork() != 0) exit(0);
    /* change process group */
    if (setpgrp(0,getpid())== -1)
      PrintLogCon(msglog,"setpgrp failed [%s]\n",SYSERR);
    /* make sure we don't have a control terminal */
    if ((ftty=open("/dev/tty",O_RDWR)) >= 0)
    {
      /* lose terminal */
      ioctl(ftty,TIOCNOTTY,0);
      close(ftty);
    }
    /* close all open files */
    for (ftty=0;ftty<_NFILE;++ftty) close(ftty);

The problem is that when it first starts up it runs fine and
looks like this with ps:

mfg      10486  0.0  2.5 1812  488 ?  S     0:00 station3b -display 138.43.2.6:

but after some period of time (usually 24 hours) the load average
of the system goes up and the application gets niced. If I try to
manually un-nice the application the nice runs without complaining
but has no effect.

mfg      10486  7.8  1.3 2264  252 ?  R N 875:54 station3b -display 138.43.2.6:

The application does use a port on a DecServer 200. As in most X applications
this process should be sitting in a select system call waiting for something
to do. 
 
Has anyone seen similar symtoms or have any ideas that I could try?

-glenn