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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!madd
From: madd@bu-cs.BU.EDU (Jim Frost)
Newsgroups: comp.unix.questions,comp.unix.wizards,comp.unix.xenix
Subject: Re: Getting rid of a <defunct> process
Message-ID: <27866@bu-cs.BU.EDU>
Date: 12 Feb 89 18:09:12 GMT
References: <102@avatar.UUCP>
Reply-To: madd@bu-it.bu.edu (Jim Frost)
Followup-To: comp.unix.questions
Distribution: usa
Organization: Associative Design Technology
Lines: 32

In article <102@avatar.UUCP> kory@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@bu-it.bu.edu