So each isn't thread safe. That brings us to keys. Is keys uninterruptible, or just the parts that would cause corruption?

Update: No, keys isn't thread safe either. 

use strict;
use warnings;
use threads;
use threads::shared;
use feature qw( say );

use constant NUM_THREADS => 10;

my %h :shared = map { $_ => 1 } 'a'..'z';
my $size = () = keys(%h);

my $done :shared;
my @threads;
for (1..NUM_THREADS) {
    push @threads, async {
       while (!$done) {
          my $test_size = () = keys(%h);
          if ($test_size != $size) {
             warn("$test_size != $size\n");
             return;
          }
       }
    };
}

sleep(10);
$done = 1;
$_->join() for @threads;

[download]
11 != 26
42 != 26
15 != 26
38 != 26
13 != 26
41 != 26
15 != 26
41 != 26
13 != 26
45 != 26

[download]

In reply to Re^5: threads::shared - when to lock a hash ? by ikegami
in thread threads::shared - when to lock a hash ? by Anonymous Monk

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.