When does a process become defunct

[Ramprasad A Padmanabhan]

Hi all,
  I am writing a daemon in perl , where the parent just forks on some
requests and the children take over. But I found many child processes
becoming defunct. I am not sure why. I am catching SIG_CHLD alright.

To reproduce the problem I have just written a skeleton of my script.
The parent process just forks 20 child processes which just sleep and
exit after some random seconds. When I run this too I find some defunct
processes, the problem is I do not get defunct processes everytime. So
this behaviour is not reproducible ( at least with my script :-) )

I am using perl 5.83  on linux ( fedora-3)

Can someone help me out avoiding these zombies

Thanks
Ram

------------------------------------ MY SCRIPT HERE ---------
use strict;
$GLOBAL::NUM_CH =0;
$|=1;
$SIG{CHLD}=\&count_ch;

foreach(1..20){
  unless(fork()){
    sleep int(rand(20));
    exit 0;
  }
  print "No of children running now " . ++$GLOBAL::NUM_CH . "\n";
  sleep 2;
}

foreach (1..100){ 
  print "PARENT CHECK LOOP: No of children running now " .
$GLOBAL::NUM_CH . "\n";
  exit(0) unless($GLOBAL::NUM_CH);
  sleep 5;
}

print "Oops : Something went wrong Not all children have quit\n";

sub count_ch { 
  print "1 CHILD QUIT: No of children running now " . --$GLOBAL::NUM_CH
. "\n";
  wait();
}

--------------------------------- END OF SCRIPT --------


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