Unsetting HANDLE_FLAG_INHERIT works! 
open my $oldin, '<&', \*STDIN or die $!;

pipe my($r), my ($w) or die $!;
open STDIN, '<&', $r or die $!;

my $wh = FdGetOsFHandle(fileno $w);
SetHandleInformation($wh, HANDLE_FLAG_INHERIT, 0);

my $pid = system 1, 'perl -ne print';
print "pid: $pid\n";

close STDIN or die $!;
open STDIN, '<&', $oldin;

close $r or die $!;
print {$w} "hello world! ($_)\n" for 0..9;
close $w or die $!;

print "waiting for slave process\n";
waitpid $pid, 0 or die $!

[download]

In reply to Re^2: Windows and pipes that don't close (close-on-exec) by salva
in thread Windows and pipes that don't close by salva

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.