I'm pretty green and novice-like on PERL. I migrated a 10+ year old Perl script from Solaris 10 (!) to RHEL 7.3, Perl (v5.8.8) to (v5.16.3). It mostly runs great but I continue to have recurring problems with defunct processes. I've read tons of articles on threads, join, $SIG{CHLD} = 'IGNORE', etc. I basically understand I'm not reaping child processes correctly but am way over my head on how to correct it. I could take a week or two to bone up but I hope someone will have pity on this poor beggar and help me out.

The script kicks off a bunch of child processes. They do their thing and the main script SEEMs to try to clean up a bit by simply doing a "join" on each child. This worked fine on the old system. Now, it only seems to work OK when the number of children is small--say less than 50--but seems to result in defuncts when the "family" is much bigger than around 50.

Here are what I think are the salient bits of code. Can you help? I THINK I need to do a "wait" or a $SIG{CHLD} = 'IGNORE', but I don't know enough to just try things. Can you help? Here's where the kids get born: 

...
use threads;
...
BEGIN {
   $Config{useithreads} or die "Recompile Perl with threads!";
} # end BEGIN
...
   switch($action) {
      case /adminpass(,|$)/ {
         print "Do adminpass ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&adminpass);
         next;
      } # end case /adminpass/
      case /backup(,|$)/ {
         print "Do backup ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&backup);
         next;
      } # end case /backup/
      case /buildhosts(,|$)/ {
         print "Do buildhosts ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&buildhosts);
         next;
      } # end case /buildhosts/
      case /buildhostsdell(,|$)/ {
         print "Do buildhostsdell ($hostname)\n" if($verbose || $debug
+);
         $t[++$#t]=threads->new(\&buildhostsdell);
         next;
      } # end case /buildhostsdell/
etc...

[download]

They do their thing in their respective subroutines, then the main thread does the following in efforts to clean up. 


# Loop through all the threads
my $thr;
foreach $thr (threads->list) {
   # Don't join the main thread or ourselves
   if ($thr->tid && !threads::equal($thr, threads->self)) {
      $x=$thr->join;
      print 'TID ' . $thr->tid() . " returned: $x\n" if($verbose || $d
+ebug);
   } # end if
} # end foreach

# Exit the script cleanly
exit 0;

[download]

I REALLY appreciate your help!

In reply to defunct process are WAY beyond my experienc by cristj1

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