However, I'm beginning to suspect that occasionally (maybe when the web server is busy) the flock call fails.

If you're unable to show us code (or even if you are), it sounds like this calls for a basic debugging technique: strip extraneous stuff out, and see if you can come up with a small example that demonstrates the problem. Quite often, the act of removing stuff that you think isn't part of the problem either reveals that some of it really is. Or, the real problem is laid bare.

Since you're working with CGIs, that might mean figuring out some way of programmatically driving the web server (e.g., by multiple LWP clients).

In reply to Re: Can flock occasionally fail on systems that support file locking? by dws
in thread Can flock occasionally fail on systems that support file locking? by rzward

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.