Getting rid of a <defunct> process

[Jim Frost]

In article <102 at avatar.UUCP> kory at avatar.UUCP (Kory Hamzeh) writes:
|I have written an application which forks and execs off many subtasks.
|The main process (the parent which does all of the forks) can not
|do a wait() because I can't get blocked for anything. Well, this results
|in a lot of "<defunct>" processes in the process table when the child
|exits.
|
|Is there any way to get rid of these processes? If not, will they take
|up any core space? I assume they will take up a slot in the process table.

What I usually do is:

	fireman() /* catches falling children */
	{ union wait wstatus;

	  while (wait3(&wstatus, WNOHANG, NULL) >= 0)
	    ;
	}

	main()
	{
	  signal(SIGCHLD, fireman);

          /*...*/
        }

<defunct> processes (also called "zombies") definitely take up process
table entries and probably take up many more resources.  Exactly what
a zombie process holds depends on the operating system implementation.

jim frost
madd at bu-it.bu.edu