And perhaps Parallel::ForkManager can ease your task.

The parent process could store all PIDs of its children, and every time a child terminates, it would remove the respective PID from that set in the SIGCHLD handler (waitpid returns the PID of the deceased process). When the set is empty, all immediately forked processes are gone.

lhp@nereida:~/Lperl/src/perl_networking/ch2$ cat -n flock.pl
 1  #!/usr/bin/perl -w
 2  use strict;
 3  use Fcntl qw(:DEFAULT :flock);
 4  use POSIX qw(WNOHANG);
 5  $| = 1;
 6
 7  local $SIG{CHLD} = sub {
 8    while (my $kid = waitpid(-1, WNOHANG) > 0) {}
 9  };
10
11  sub create_child {
12    my ($id, $task) = splice @_, 0, 2;
13    my $pid;
14
15    return $pid if $pid = fork();
16    die "Cannot fork $!" unless defined $pid;
17    $task->($id, @_); # do something
18    exit;
19  }
20
21  sub parfor {
22    my $LAST = shift;
23    my $task = shift;
24    my @pid;
25
26    $pid[0] = $$;
27    $pid[$_] = create_child($_, $task, @_) for 1..$LAST;
28    return @pid;
29  }
30
31  sub task {
32    my $id = shift;
33    my $fn = shift;
34
35    sleep(int(rand(2)));
36    open my $f, "+<$fn" or die "Can't open $fn. $!\n";
37    flock($f, 2);
38    seek $f, 0, 0;
39    my $num = <$f>;
40    warn "Process $id reads $num.\n";
41    seek $f, 0, 0;
42    my $s = $num+$id;
43    warn "Process $id writing $s.\n";
44    print $f $s;
45    close($f);
46    exit;
47  }
48
49  #main
50  my $np = shift || 3;
51  my $fn = shift || "sync.txt";
52  open my $f, "> $fn" or die "Can't open file $fn. $!\n";
53  print $f 0;
54  close($f);
55  &parfor($np, \&task, $fn);
56  do {} while wait > 0;
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Hope it helps

Casiano

use forks;
my $max_threads = 30;
for( 1...$max_threads )
{
  threads->create( \&munge_files, shift(@files_to_munge) );
}# end for()

# Wait for our threads to finish:
$_->join foreach threads->list;

# All done!
print "Job was completed.\n";

sub munge_files {
  my ($file) = @_;
  # Do stuff with $file...
}
[download]

It works really well and i have been happy with it! It cut the processing time in the application from 45 minutes to about 15!!