Chad Kellerman wrote:
>
> I know this is very confusing. And I might not even be posting to the
> right
> list. But I am so frustrated with trying to get this thing to work. It
> seems as if I have searched everywhere for examples of limiting the number
> of forked processes, then being able to fork with in a fork.
> I originally was using Parallel::ForkManager. But I found that if I
> set
> the max_processes to 8 it will start eight but will not contiue until all
> eight were done, then only do one at a time.
>
the following probably does what you want. it creates 8 child processes to
begin with and as those child process dies, it creates more. you will
always have 8 child processes at a time:
#!/usr/bin/perl -w
use strict;
use POSIX ':sys_wait_h';
my $child = 0;
my $pid = 0;
sub more_child{
$pid = fork;
die("fork failed\n") unless(defined $pid);
if($pid){
print ++$child," child ($pid)\n";
}else{
sleep(1) for(1..3);
exit;
}
}
$SIG{CHLD} = sub { while((my $c=waitpid(-1,&WNOHANG)) > 0){
print "$c finished\n"; --$child; more_child} };
while(1){
for(1..8){
more_child;
while($child == 8){select(*I,*J,*K,0.5)}
}
}
__END__
if you check the process with ps or top, you will see there are always 9
processes at a time (1 parent + 8 children). in my linux box, it prints:
Name "main::K" used only once: possible typo at ./tmp.pl line 60.
Name "main::J" used only once: possible typo at ./tmp.pl line 60.
Name "main::I" used only once: possible typo at ./tmp.pl line 60.
1 child (9829)
2 child (9830)
3 child (9831)
4 child (9832)
5 child (9833)
6 child (9834)
7 child (9835)
8 child (9836)
9830 finished
9836 finished
7 child (9838)
9835 finished
7 child (9839)
9834 finished
7 child (9840)
9833 finished
7 child (9841)
... etc
the first 8 lines are the initial 8 children and the rest are those children
created to replace the dead ones. the warnings are coming from select which
aren't really relevant in this example.
david
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