I would start with code in the flock documentation and work from there.

I would also try to be sure that nobody else is trying to write to the file. You might be able to ensure that by changing the filename that you write to. That is, instead of writing to "report", change it to "report-locksafe" in the places where you're doing locking. If you see something show up in "report" anyway, there's another writer somewhere.

Also, the "do or die" idiom is good here. Check to see if your flock fails and be sure to output $! if it does.

In reply to Re: What the flock!? Concurrency issues in file writing. by kyle
in thread What the flock!? Concurrency issues in file writing. by suaveant

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.