Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
My problem/confusion can be illustrated with the code below:
#!/usr/bin/perl use strict; use threads; use threads::shared; my %h:shared; for (0..10) { $h{$_}=&share({}); } for (keys(%h)) { print "$h{$_}\n"; }
On my system, I get:
HASH(0x9904d20) HASH(0x9904d38) HASH(0x9904d14) HASH(0x9904d2c) HASH(0x9904d08) HASH(0x9904d20) HASH(0x9904d38) HASH(0x9904d14) HASH(0x9904d2c) HASH(0x9904d08) HASH(0x9904d20)
Now, obviously, the addresses change with each invocation, but it is always 5 unique addresses that repeat. It seems to be creating 11 distinct hashes where I can file away my scalars, but it doesn't make sense to me that there would only be 5 unique memory addresses. Now, mysteries like this always bother me, but beyond the mystery, this behavior breaks XML::Dumper as it uses the memory address to ensure that a data structure that is referenced multiple times is only dumped once. Without the threads::shared module, I get 11 distinct memory locations as I would expect as illustrated below:
#!/usr/bin/perl use strict; my %h; for (0..10) { $h{$_}={}; } for (keys(%h)) { print "$h{$_}\n"; }
HASH(0x9ea67c8) HASH(0x9ea6720) HASH(0x9ea67b0) HASH(0x9ec8578) HASH(0x9ea66e4) HASH(0x9ea672c) HASH(0x9ea5b44) HASH(0x9ea69a8) HASH(0x9ea6600) HASH(0x9ec8590) HASH(0x9ea6990)
What am I missing? Is there a good reason for this behavior? It has rendered XML::Dumper useless for me.

In reply to mysterious threads::shared behaviour by ericatkin

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, 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
  • 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.
  • Log In?

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

    How do I use this? | Other CB clients
    Other Users?
    Others chanting in the Monastery: (4)
    As of 2019-11-13 22:32 GMT
    Find Nodes?
      Voting Booth?
      Strict and warnings: which comes first?

      Results (74 votes). Check out past polls.