Your best bet may be to trim down your SIGCHLD handler as much as possible. If there's no-way getting around doing a bunch of work when your child process ends, you may want to consider doing something like queing the info you need from the deceased child process and do the work a little later on (once you're out of the signal-handler).

Seeing the code for your SIGCHLD handler (or giving us an idea of what it is doing) may help the Monestary assist you in your quest.

use POSIX;
%SIG{'CHLD'} = \&REAPER;
#signal routine to wait for all children (prevents zombies)
sub REAPER
{   
    #WNOHANG means to return immediately if no child has exited.
    while ((waitpid(-1, WNOHANG)) >0 )
    { } 
    
    #reset the sig for the next child to die;
    $SIG{CHLD} = \&REAPER;
}
[download]

$SIG{CHLD} = \&REAPER;

# waitpid code goes here
[download]

The Perl Cookbook advises being paranoid and always reinstalling your SIG handler as the first step of your signal handler except in the case of SIGCHLD for the following reason:

If you re-install the SIGCHLD handler before wait or waitpid gets its information from the OS's process table you risk the child becoming a zombie. Recomended is the following: Loop in the SIGCHLD handler and only re-install the SIGCHLD handler after the loop is complete (code below taken from Perl Cookbook).

$SIG{CHLD}=\&REAPER;
sub REAPER{
  my $stiff;
  while(($stiff = waitpid(-1,&WNOHANG))>0){
    # do something with $stiff if you want
  }
  $SIG{CHLD}=\&REAPER;
}
[download]

This is necessary because most OSes will not queue up signals so if 2 are sent to your process at aprox the same time your process may behave as if it has received only 1.

This may point to a possible solution to the original problem:

$SIG{CHLD}=\&REAPER;
sub REAPER{
  $SIG{CHLD}='IGNORE';
  my $stiff;
  while(($stiff = waitpid(-1,&WNOHANG))>0){
    # do something with $stiff if you want
  }
  $SIG{CHLD}=\&REAPER;
}
[download]

For a detailed discussion see sections 6.17 thru 6.19 (espscially 6.19) of the Perl Cookbook.