in reply to 5:10: Why is this slower than 5.8.8?

Try compiling both perls with usemymalloc=y. FreeBSD's malloc may be very slow in some situations.
  • Comment on Re: 5:10: Why is this slower than 5.8.8?

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Re^2: 5:10: Why is this slower than 5.8.8?
by jk2addict (Chaplain) on Dec 23, 2007 at 17:06 UTC
    Thanks for that thought. I'll give that a try for sure. If using FreeBSD malloc solves the problem, I'd vote that it should be the default in Configure given the nature of the 50% performance difference for a common idiom.
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      s/solves/causes/

      Perl's malloc is fine.

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        Try to compile 2 versions of perl5.8 on FreeBSD - one with mymalloc, other - without. And then compare their perfomances. You will be very dissapointed. The one which uses FREEBSD's malloc will be 20-30% faster in almost any operations.
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Re^2: 5:10: Why is this slower than 5.8.8?
by Anonymous Monk on Dec 23, 2007 at 17:39 UTC
    usemymalloc=y will bring 20-30% more perfomance penalty! This is stupid trying to solve one slowdown by another slowdown. FreeBSD's malloc is faster than perl's malloc anyway.
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      Well, then try the following script 
      my $max = 50000;
my @l = ('a'..'z');
my @keys = map { join '', map $l[rand @l], 0..71 } 0..$max;

      [download]
      On my system running this script with a perlmalloc-built perl is 600x (!) faster than with a sysmalloc-built perl: 
      $ time /usr/local/src/perl-5.10.0-perlmalloc/perl -I/usr/local/src/per
+l-5.10.0-perlmalloc/lib ~/trash/slow_malloc2.pl
3.027u 0.435s 0:03.68 93.7%     1448+324155k 0+0io 0pf+0w

$ time /usr/local/src/perl-5.10.0-sysmalloc/perl -I/usr/local/src/perl
+-5.10.0-sysmalloc/lib ~/trash/slow_malloc2.pl
405.090u 189.574s 13:01.52 76.0%        1466+495449k 0+0io 0pf+0w

      [download]
      This is a pathological case, but this may happen with FreeBSD's malloc.
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[d/l]
[select]
        You found one case on 10000. Other 9999 cases is slower with perl's malloc. And this is not the subject of the topic! Class::Accessor::Grouped anyway runs faster without perl's malloc and the problem is not in the type of malloc.
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