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Postings from March 2013
On Mon, 25 Mar 2013 20:47:39 -0400, Eric Brine <ikegami@adaelis.com>
wrote:
> On Sun, Mar 24, 2013 at 4:00 PM, bulk88 <bulk88@hotmail.com> wrote:
>
> > Konovalov, Vadim (Vadim)** CTR ** wrote:
> >
> >> It was clearly and unambiguously a patch. It wasn't in diff format, but it
> >>> was clearly indicating that to make your code more portable, you could
> >>> change the line:
> >>>
> >>> HE *hes [count];
> >>> to
> >>> #if defined(__BORLANDC__) || defined(_MSC_VER) || defined(__STDC__)
> >>> HE **hes = Perl_malloc (count * sizeof (HE));
> >>> #else
> >>> HE *hes [count];
> >>> #endif
> >>>
> >>
> >> 1)
> >> an overlook - it should be HE **hes = Perl_malloc (count * sizeof
> >> (HE*));
> >>
> >> it appears that HE is larger than HE* and allocating more memory, hence
> >> misbehaviour is not noticed, but anyway, this isn't correct
> >>
> >> 2) when that chunk of memory freed? TIA :)
> >>
> >
> > alloca, it can never leak. A non-const length auto C array calls alloca
> > anyway on C99 under the hood.
>
> I think he's asking about the newly introduced Perl_malloc
I tested this yesterday with this code:
--8<---
my $n = 100;
foreach my $f (qw( test1.json test2.json )) {
say "Testing $f";
my $jsn = do { open my $fh, "<", $f; local $/; <$fh> };
printf "Length: %9d\n", length $jsn;
my $x = decode_json ($jsn);
printf "Size D: %9d\n", total_size ($x);
printf "Size E: %9d\n", length encode_json ([$x]);
my $td = 0;
for (1..$n) {
my $t0 = [ gettimeofday ];
$x = decode_json ($jsn);
$td += tv_interval ($t0);
}
printf "%s: decode %10.6f s/run\n", $f, $td / $n;
my $te = 0;
for (1..$n) {
my $t0 = [ gettimeofday ];
my $j = encode_json ([$x]);
$te += tv_interval ($t0);
}
printf "%s: encode %10.6f s/run\n", $f, $te / $n;
}
-->8---
on two relative big json files test1.json is unformatted (no newlines
and whitespace) test2.json is formatted (prettied)
-rw-rw-rw- 1 merijn users 716642 Mar 25 18:40 test1.json
-rw-rw-rw- 1 merijn users 14776790 Mar 25 18:40 test2.json
Testing test1.json
Length: 716642
Size D: 2240594
Size E: 716589
test1.json: decode 0.010089 s/run
test1.json: encode 0.003995 s/run
Testing test2.json
Length: 14776790
Size D: 28672598
Size E: 8198965
test2.json: decode 0.157494 s/run
test2.json: encode 0.042437 s/run
Then changed the code to (note the (HE *) and the dropped _ for
Linux/gcc. Used alloca, not Perl_malloc. I know I should look at
*en*coding timings only.
#if defined(__BORLANDC__) || defined(_MSC_VER) || defined(__STDC__)
HE **hes = alloca (count * sizeof (HE *));
#else
HE *hes [count]; // if your compiler dies here, you need to enable C99 mode
#endif
and got
Testing test1.json
Length: 716642
Size D: 2240594
Size E: 716589
test1.json: decode 0.010471 s/run
test1.json: encode 0.003938 s/run
Testing test2.json
Length: 14776790
Size D: 28672598
Size E: 8198965
test2.json: decode 0.156661 s/run
test2.json: encode 0.041112 s/run
Then with Perl_malloc
#if defined(__BORLANDC__) || defined(_MSC_VER) || defined(__STDC__)
HE **hes = Perl_malloc (count * sizeof (HE *));
#else
HE *hes [count]; // if your compiler dies here, you need to enable C99 mode
#endif
which resulted in
Testing test1.json
Length: 716642
Size D: 2240594
Size E: 716589
test1.json: decode 0.009939 s/run
test1.json: encode 0.003932 s/run
Testing test2.json
Length: 14776790
Size D: 28672598
Size E: 8198965
test2.json: decode 0.157021 s/run
test2.json: encode 0.041158 s/run
which is still faster than the original code.
gcc (SUSE Linux) 4.7.2 20130108 [gcc-4_7-branch revision 195012]
This is perl 5, version 16, subversion 3 (v5.16.3) built for i686-linux-64int
Linux 3.7.10-1.1-desktop [openSUSE 12.3 (Dartmouth)] i386 Core(TM) i7-2620M CPU @ 2.70GHz/800(4) i686 8042 Mb
--
H.Merijn Brand http://tux.nl Perl Monger http://amsterdam.pm.org/
using perl5.00307 .. 5.17 porting perl5 on HP-UX, AIX, and openSUSE
http://mirrors.develooper.com/hpux/ http://www.test-smoke.org/
http://qa.perl.org http://www.goldmark.org/jeff/stupid-disclaimers/
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