Hi,

I have quite a large file, appx. 4 GB. I am running on a cluster, so memory is not an issue. So, I went ahead and buffered the whole file on to a variable. I hope this is much better than reading line by line?

My task is this: From the second line of the file $i=1, I read from then on every 4th line, $i=1,5,9,13 etc... and then check for some patterns and do some operations depending on if the pattern was present on not, replacing strings etc...

Now, since mostly these operations are independent, that is; the pattern check on line 2 ($i = 1) could be done independent of line 6 ($i=5) and so on.. is it possible to create something like threads or do multiple checks at the same time? If its possible, then reading data in small chunks and assigning them to each thread would be a good idea; the number of threads would depend of course on the total memory available.

I hope my questions is clear, if not, please point it out and I'll try to clarify. Its just that I have the resources and I wonder if it couldn't be run other than in a total sequential manner.

Thank you!

In reply to buffering from a large file by cedance

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.