Re: Small Process Killing Question

[Peter Philipp <pjp@dega.daemonium.com>]

On Tue, Jan 16, 2001 at 08:28:54PM -0700, Kenneth Ingham wrote:
> You do not need to reboot to get rid of zombies.  They occur when the
> parent does not wait(2) (or waitpid(2)) for them.  Using ps, find the
> parent process ID (PPID) and kill *it*.  Then init will inherit the
> zombies and clean them up.

Perhaps I can add some example to the conversation.

A ps -axl output shows 3 (of really 128) zombied childs with random pids and
a parent process id of 21098 which after forking is forced to sleep forever
and never wait (hence all these little zombies).

 1000   204 21098   0  28 20     0     0 -      Z+    p5    0:00.00 (forkb)
 1000   445 21098   0  28 20     0     0 -      Z+    p5    0:00.00 (forkb)
 1000   503 21098   0  28 20     0     0 -      Z+    p5    0:00.00 (forkb)

After killing the parent the init process inherets the crying orphaned zombie
childs and reaps them out of their ill misery (I just love writing that 
sentence).

> kill -9 21098 ; ps axl |grep forkb | head
 1000   162 24191   0  28 20   504     0 -      RV    p1    0:00.00 grep forkb

Here is the source code of my example:

----
int
main(void)
{
        int i = 128;
        pid_t pid;

        for (; i ; i--) {
                switch(pid = fork()) {
                case -1:
                        fprintf(stderr, "couldn't fork: %s\n", strerror(errno));
                        exit(1);
                case 0:
                        sleep(10);
                        exit(0);
                }
        }

        /* forked 128 times children are dead and we don't care what happens to
         * us we just loop forever
         */

        for(;;) sleep(1);
}
----


Cheers,

-- 
-                                                                              -
Peter Philipp <pjp@daemonium.com>
Daemonium