Thanks! ikegami!

open(my $pipe, "$command |")    # 2-arg form
open(my $pipe, '-|', $command)  # 3-arg form

[download]
above looks right, this 2 arg form from OP looked weird to me: 
 
$pid=open(PARENT_READ_HANDLE, "-|");

[download]
Which as they say is neither fish or fowl (not correct 2-arg or 3 arg). I am still a bit confused as to the OP's intent here. This still appears to be a synchronous app, not client-server. There is a lot of complex stuff that doesn't appear to be necessary.

In reply to Re^3: Issue with communication of large data between Parent and child using Perl pipes by Marshall
in thread Issue with communication of large data between Parent and child using Perl pipes by waavman

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.