You're misunderstanding what Parallel::ForkManager does, I'm afraid. (As long as it actually does use fork, which seems likely from the name).

When fork() (the underlying system call) is called, the process is split into 2 identical copies, and the fork call returns in each copy, indicating by its return value which copy is which. (That's a simplified view, but it'll do for now)

So your concatentate_parallel function is effectively adding a letter to $content in each subprocess, but that doesn't affect the parent process (your main application) where $content remains unchanged.

You can find a lot of good info online about how fork works, what the variants are, what gets copied for subprocesses and what doesn't. It's a good thing to understand.

By the way, if you'd been using threads instead, you'd have been on the right path. Threads are simultaneous paths of execution in the _same_ process, so different threads could modify $content. But without using synchronization mechanisms, you're right, the letters would arrive in a jumbled, unpredictable order.

Good luck!


Mike

In reply to Re: using Paralell::ForkManager to concatenate a string, where order of concatenation doesn't matter by RMGir
in thread using parallel processing to concatenate a string, where order of concatenation doesn't matter by tphyahoo

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.