Re: Convert string to array - performance challenge

For that input, split is the fastest for me.

           Rate    regex unpack_C unpack_a    split
regex    9.95/s       --      -2%     -46%     -50%
unpack_C 10.1/s       2%       --     -45%     -49%
unpack_a 18.3/s      84%      80%       --      -9%
split    20.0/s     101%      97%       9%       --
[download]

use strict;
use warnings;

use Benchmark qw( cmpthese );

my %tests = (
   split    => q{ my @a = split //, $buf;             },
   regex    => q{ my @a = $buf =~ /./sg;              },
   unpack_C => q{ my @a = map chr, unpack 'C*', $buf; },
   unpack_a => q{ my @a = unpack '(a)*', $buf;        },
);

$_ = "use strict; use warnings; our \$buf; $_ 1"
   for values(%tests);

local our $buf = "abcdef\x00ghik" x 10_000;
cmpthese(-2, \%tests);
[download]

Update: Changed (A)* to (a)* in response to BrowserUk's reply.

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Re^2: Convert string to array - performance challenge by BrowserUk (Patriarch) on Apr 07, 2010 at 17:55 UTC
There is a problem with using `unpack '(A)'`: `[0] Perl> $buf = "abcdef\x00ghik";; [0] Perl> @a = unpack '(A)', $buf;; [0] Perl> print length for @a;; 1 1 1 1 1 1 0 1 1 1 1` [download]	[reply] [d/l] [select]
Re^2: Convert string to array - performance challenge by Marshall (Canon) on Apr 08, 2010 at 06:52 UTC
Very interesting! With the EXACT same code as Ikegami, (with the (a)* mod), I get: `Rate regex split unpack_C unpack_a regex 3.00/s -- -3% -9% -19% split 3.09/s 3% -- -6% -17% unpack_C 3.29/s 10% 7% -- -11% unpack_a 3.71/s 24% 20% 13% --` [download] I have seen before that the Ikegami machine is faster than mine on certain benchmarks. But, I am unable to understand how split() can be the fastest. I am running a Prescott processor, an old 3 Ghz hyper-threaded critter. With Active State Perl 5.10.1.	[reply] [d/l]
Re^3: Convert string to array - performance challenge by Anonymous Monk on Apr 08, 2010 at 07:08 UTC
I think it depends a lot on the system, c-runtime ActivePerl v5.8.9 built for MSWin32-x86-multi-thread, Binary build 825 + [288577] Rate unpack_C unpack_a split regex unpack_C 3.48/s -- -5% -7% -9% unpack_a 3.66/s 5% -- -3% -4% split 3.76/s 8% 3% -- -1% regex 3.82/s 10% 4% 1% -- Rate unpack_C regex unpack_a split unpack_C 3.56/s -- -5% -5% -6% regex 3.74/s 5% -- -0% -1% unpack_a 3.74/s 5% 0% -- -1% split 3.79/s 7% 2% 1% -- Rate split unpack_C regex unpack_a split 3.45/s -- -4% -9% -25% unpack_C 3.58/s 4% -- -6% -22% regex 3.79/s 10% 6% -- -18% unpack_a 4.60/s 34% 29% 21% -- [download] The newer versions (built using MinGW) are more consistent between runs `C:\perl\5.10.1\bin\MSWin32-x86-multi-thread\perl.exe Rate unpack_C regex split unpack_a unpack_C 3.66/s -- -2% -15% -22% regex 3.74/s 2% -- -14% -21% split 4.33/s 18% 16% -- -8% unpack_a 4.70/s 28% 26% 9% -- C:\perl\5.11.1\bin\MSWin32-x86-multi-thread\perl.exe Rate regex unpack_C split unpack_a regex 2.74/s -- -28% -38% -39% unpack_C 3.82/s 39% -- -13% -14% split 4.40/s 60% 15% -- -2% unpack_a 4.47/s 63% 17% 2% --` [download]	[reply] [d/l] [select]
Re^4: Convert string to array - performance challenge by BrowserUk (Patriarch) on Apr 08, 2010 at 07:23 UTC
I see some variablility, but nothing like those levels using AS perls. AS1007 64-bit: c:\test>junk Rate regex unpack_C unpack_a split regex 7.95/s -- -1% -10% -14% unpack_C 8.01/s 1% -- -10% -14% unpack_a 8.88/s 12% 11% -- -4% split 9.30/s 17% 16% 5% -- c:\test>junk Rate regex unpack_C unpack_a split regex 7.95/s -- -0% -8% -12% unpack_C 7.95/s 0% -- -8% -12% unpack_a 8.68/s 9% 9% -- -4% split 9.09/s 14% 14% 5% -- c:\test>junk Rate unpack_C regex unpack_a split unpack_C 8.02/s -- -0% -9% -11% regex 8.02/s 0% -- -9% -11% unpack_a 8.81/s 10% 10% -- -2% split 9.02/s 13% 13% 2% -- c:\test>junk Rate unpack_C regex unpack_a split unpack_C 7.95/s -- -0% -9% -13% regex 7.95/s 0% -- -9% -13% unpack_a 8.74/s 10% 10% -- -5% split 9.16/s 15% 15% 5% -- [download] AS826 32-bit: c:\test>\perl32\bin\perl junk.pl Rate unpack_C split regex unpack_a unpack_C 8.38/s -- -5% -9% -15% split 8.81/s 5% -- -5% -11% regex 9.23/s 10% 5% -- -6% unpack_a 9.86/s 18% 12% 7% -- c:\test>\perl32\bin\perl junk.pl Rate unpack_C split regex unpack_a unpack_C 8.45/s -- -5% -8% -15% split 8.87/s 5% -- -3% -11% regex 9.16/s 8% 3% -- -8% unpack_a 9.94/s 18% 12% 9% -- c:\test>\perl32\bin\perl junk.pl Rate unpack_C split regex unpack_a unpack_C 8.38/s -- -5% -8% -14% split 8.81/s 5% -- -4% -10% regex 9.16/s 9% 4% -- -6% unpack_a 9.78/s 17% 11% 7% -- c:\test>\perl32\bin\perl junk.pl Rate unpack_C split regex unpack_a unpack_C 8.38/s -- -5% -8% -14% split 8.81/s 5% -- -4% -10% regex 9.16/s 9% 4% -- -6% unpack_a 9.78/s 17% 11% 7% -- [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l] [select]
Re^5: Convert string to array - performance challenge by ikegami (Patriarch) on Apr 08, 2010 at 16:54 UTC