Beefy Boxes and Bandwidth Generously Provided by pair Networks
The stupid question is the question not asked

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
OK, I just made up a quick test case:
use strict; use warnings; use Benchmark 'cmpthese'; cmpthese(10000, { 'eval' => sub { eval_code() }, 'noeval' => sub { no_eval_code() },, }); sub eval_code { my $x = 0; for (1..1000) { eval { $x+=1; } } } sub no_eval_code { my $x = 0; for (1..1000) { $x+=1; } }
And, unless I've missed something blindingly obvious, in this trivial case there is quite an overheard with eval:
Rate eval noeval eval 1495/s -- -62% noeval 3953/s 164% --
But let's tweak that for a real life example. Here's some code where it "dies" one time in ten:
use strict; use warnings; use Benchmark 'cmpthese'; cmpthese(1000000, { 'eval' => sub { eval_code() }, 'noeval' => sub { no_eval_code() },, }); sub eval_code { my $x = 0; for (reverse 0..9) { eval { my $x = 100/$_; }; if ($@) { error_sub(); } } } sub no_eval_code { for (reverse 0..9) { if ($_==0) { error_sub(); } else { my $x = 100/$_; } } }
and here's the benchmark results:
Rate eval noeval eval 67797/s -- -39% noeval 111111/s 64% --
Well. That's still significantly faster. So have I proved eval slows things down, or is this a case specific example that someone can find a counter-example for? I've been bitten by benchmarks on code snippets before, so I'm still wary of this result. Hmmmmm....

In reply to Re: Nested evals - are they evil? (sample benchmarks) by cLive ;-)
in thread Nested evals - are they evil? by cLive ;-)

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others taking refuge in the Monastery: (4)
    As of 2018-02-21 07:52 GMT
    Find Nodes?
      Voting Booth?
      When it is dark outside I am happiest to see ...

      Results (276 votes). Check out past polls.