Re-reading your post, I should also comment on:

I had tried using a simple shared scalar before, but I thought I had to use cond_wait() and locking and friends

Technically, you should use locking on shared vars.

You will rarely, if ever, need to use cond_*(), and I would suggest you pretend they don't exist until you encounter the situation that you cannot deal with without them.

I write a lot of threaded code, and I've only had to use them about 3 or 4 time in total over the past 8 or 9 years.

For this specific case, even the need for lock is moot. The shared var is either true or false. When the value is about to change, readers will either see it just before it changes and loop once more, or they will see it just after it changed and terminate.

Locking it before changing it; or before reading it; will make no quantifiable difference to the order in which things happen; it is therefore redundant -- in this case!

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.

The start of some sanity?

In reply to Re^3: failing with Thread::Queue by BrowserUk
in thread failing with Thread::Queue by rastoboy

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.