$manager->finish(\&next); is exit(\&next). Aside from the fact that the argument makes no sense, you're exiting the child at the wrong spot. When that child is done processing a line, it needs to exit by calling finish. 

use Parallel::ForkManager;

my $manager = new Parallel::ForkManager( 20 );

while (<LIST>){
    $manager->start and next;

    my (..., $ip, ...) = split( /\s+/, $_ );
    print "ip ? $ip\n";
          
    $manager->finish() if !$p->ping($ip);

    ...

    $manager->finish();
}
 
print "flag\n";

[download]

In reply to Re: Strange (for me) behavior of Parallel::ForkManager by ikegami
in thread Strange (for me) behavior of Parallel::ForkManager by Sterh

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.