in reply to Re^4: Should I just print my own HTTP headers?
in thread Should I just print my own HTTP headers?

And uphill both ways! But according to this test, printing one header by hand is 11331% more efficient than using CGI to do it. Did I miss something?

Yes, you missed something. Two things in fact - "bottleneck" and "profiled". I didn't say I'd benchmarked lots of individual lines of web-apps - I said I'd profiled lots of web-apps! When you profile you find out where the important things to tune are - the really slow things that actually matter. Things like database access, file access, search algorithms, etc. NOT things like CGI.pm!

Benchmarking is a useful tool but it's nearly useless as a way to figure out what's worth spending time optimizing. If you find yourself wanting to disagree then I suggest you stop programming in Perl immediately - C is so much faster! Just try benchmarking:

  for (0 .. 100000) { $a++; }

Versus:

  for (int x = 0; x <= 100000; x++) { a++ }

-sam

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Re^6: Should I just print my own HTTP headers?
by Cap'n Steve (Friar) on Apr 11, 2007 at 05:28 UTC
    When you profile you find out where the important things to tune are - the really slow things that actually matter.
    But what if you've already tuned the important things? We're talking about a script that probably won't exceed 30 lines so it's not exactly difficult to maintain.
    Benchmarking is a useful tool but it's nearly useless as a way to figure out what's worth spending time optimizing.
    Yes, but it is useful in that it tells you how to optimize what you've already decided to optimize. I'd love to write it in C, but 1) I don't know C. and 2) I don't know of any webhost that allows compiled programs without a dedicated server.
[reply]
      But what if you've already tuned the important things?

      Then you'd be wasting your time to optimize it further. Optimizing for developer efficiency is just as important (if not more) than optimizing for CPU time!

      We're talking about a script that probably won't exceed 30 lines so it's not exactly difficult to maintain.

      Ah, the optimism of youth. Trust me, if it's at all useful it will grow. Even if it doesn't grow, someone (maybe you) will copy and paste your nasty hack into a much larger program.

      Yes, but it is useful in that it tells you how to optimize what you've already decided to optimize. I'd love to write it in C, but 1) I don't know C.

      You should learn C. Then you'll realize that you don't want to write it (or anything) in C unless you absolutely have to. A 30 line Perl program is likely to be 300+ lines of C! The crack about C was meant to be ironic!

      -sam

[reply]
        How is "print $header;" less maintainable than "$cgi->header($header);"?

        If it grows, then I've designed the whole site wrong. If it turns out I've designed the whole site wrong, it probably won't kill me to rewrite a dozen lines to use CGI.
[reply]

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