Perl $SIG{CHLD} handler

gistfile1.pl

# see http://perldoc.perl.org/perlipc.html#Signals
# http://www.calpoly.edu/cgi-bin/man-cgi?wait+2
# and Perl Cookbook, part 16.19. Avoiding Zombie Processes

sub REAPER {
  local ($!, $?);
  while ( (my $pid = waitpid(-1, WNOHANG)) > 0 ) {
    say "Process $pid send CHLD with status $?";
    if ( WIFEXITED($?) or WIFSIGNALED($?) ) {
      if ( $kids{$pid} ) {
        process_event_from_child( $kids{$pid}, 'chld' );
      }
      else {
        say "ERROR: CHLD signal from unknown PID $pid";
      }
    }
    else {
      say "False CHLD alarm $? on $pid";
    }
  }
  $SIG{CHLD} = \&REAPER;
}