Beefy Boxes and Bandwidth Generously Provided by pair Networks
The stupid question is the question not asked
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
Should I do that explicitly?

No. Implicit closing works fine. Where the issue arises is typified by this TCP server constuction:

sub clientHandler { my( $fileno ) = shift; open my $client, ">&=$fileno" or die $!; while( <$client> ) { ...; } } while( my $client = $svr->accept ) { threads->create( \&clientHandler, fileno( $client ) ); }

The problem is that will work much of the time, especially when testing under light loads, because the thread will succeed in running to the point when the client handle is duped, before the thread that spawned it reaches the end of the while loop and the original $client is auto-closed.

But then when the program is used under moderately heavy loads, the spawning thread gets another timeslice before the spawned thread has chance to perform the dup, and by the time it does, the handle has been auto-closed and there is nothing to dup.

It becomes necessary to add a semaphore to prevent the parent thread from reaching the end of the while loop before the child has duped the handle. Not especially difficult; but there are many ways to do it wrongly.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^5: threads, file handles and wxPerl by BrowserUk
in thread threads, file handles and wxPerl by sdetweil

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!
  • 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, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others surveying the Monastery: (4)
    As of 2014-08-23 18:39 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The best computer themed movie is:











      Results (178 votes), past polls