A nice solution, but I would suggest ( as I almost always do to this kind of question ) a few improvements.

Why are you going through all this pain with REAPERs and counters? Handle the child's death yourself in the main loop of the code. This obviates some complexity and also gets around perl's rarely ( honestly, I have never seen this interupt problem in about 6 years of perl programming, but that is merely anecdotal ) seen interupt problems.

What I would suggest ( and have used several times ) is a loop like this: 

    while( $again ) {
        #--
        # Initial loop to spawn children
        #--
        if ( $ref < $max ) {
            if ( $cpid = fork ) {
                $kids{ $cpid } = 1;
            }
            else {
                #do interesting process here
                exit;
            }
            $ref++;
        }
        else {
            do {
                select undef, undef, undef, 0.5;
                $dpid = waitpid( -1, 1 );
            } until $dpid;
            last if ( $dpid == -1 );  # No children left
            delete $kids{$dpid};
            if ( $cpid = fork ) {
                $kids{ $cpid } = 1;
            }
            else {
                # Same interesting process
                exit;
            }

        }
        $total++;
    }

[download]
There is some complexity here - I was using this to seriously abuse some cycles :) The if() portion merely checks to see if all the children have been spawned. If they haven't, spawn another off and log the creation into a hash.

If all the children have been spawned, poll the system every 1/2 second until one dies. I make sure I have a real pid, dropping out of the loop if not, and remove that entry from the tracking hash. This hash can be used to log when a child has died and what it was doing. Spawn another child off and loop again.

Because I am handling the deaths myself and not waiting for quasi-mystical signals, even if 100 children die at the same time, each child will remain in the process table until I have processed it. I can then be certain that I will spawn 100 more children off, no matter how or when they die.

Oh. This loop was actually run as a child process - my loop exitted when the signal handler set $again. You can replace this with a variety of exit conditions - timeouts, all the children have been reaped, etc.

mikfire

In reply to Re: Re: controling the num of fork sessions by mikfire
in thread controling the num of fork sessions by Anonymous Monk

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