Using chdir is about twice as fast: 
$ perl chdir_benchmar
Benchmark: timing 1000 iterations of with_chdir, without_chdir...
with_chdir: 16 wallclock secs ( 8.11 usr +  8.46 sys = 16.57 CPU)
  @ 60.35/s (n=1000)
without_chdir: 31 wallclock secs (10.98 usr + 19.15 sys = 30.13 CPU)
  @ 33.19/s (n=1000)

[download]
#!/usr/bin/perl

use warnings;
use strict;
use Benchmark;

sub with_chdir
{
  my $d = shift;
  my $filecount = 0;
  chdir($d) or die "chdir: $!\n";
  opendir(DIR,".");
  while(my $f = readdir(DIR))
  {
    ( -f $f) and $filecount++;
  }
}

sub without_chdir
{
  my $d = shift;
  my $filecount = 0;
  opendir(DIR,$d);
  while(my $f = readdir(DIR))
  {
    ( -f "$d/$f") and $filecount++;
  }
}

use constant TESTDIR => "/var/mail";

timethese(100, {
                 with_chdir => sub { with_chdir(TESTDIR); },
                 without_chdir => sub { without_chdir(TESTDIR); },
                });

[download]

In reply to Re^2: The -d switch isn't working as I expected it to (test to see if its a directory) by sgifford
in thread The -d switch isn't working as I expected it to (test to see if its a directory) by heigold1

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.