Re^2: Strange performance loss after interpolating an array and then copying to another array;

Let's test that hypothesis:

use Time::HiRes qw(gettimeofday tv_interval);

my @array = (1..100);
# say "@array"; # 0.332776 s
# say @array;   # 0.052496 s
# #<nothing>    # 0.052361 s

my $t0 = [gettimeofday];

for (1..10000)
{
   my @array2 = @array;
}

say tv_interval($t0);
__END__
SV = IV(0xe47dd8) at 0xe47de8
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 1
SV = PVIV(0xe512d8) at 0xe47de8
  REFCNT = 1
  FLAGS = (IOK,POK,pIOK,pPOK)
  IV = 1
  PV = 0xe56050 "1"\0
  CUR = 1
  LEN = 16
[download]

So yes, interpolating the array into the string adds a PV (string) representation to the scalar.

Perl 6 - second systems done right

Comment on Re^2: Strange performance loss after interpolating an array and then copying to another array; Download Code

Replies are listed 'Best First'.
Re^3: Strange performance loss after interpolating an array and then copying to another array; by Kc12349 (Monk) on Aug 19, 2011 at 18:13 UTC
So what causes the performance gain, though small, going from this: `use Time::HiRes qw(gettimeofday tv_interval); my @array = (1..100); for my $element (@array) { $element .= ''; } for my $element (@array) { $element += 0; } my $t0 = [gettimeofday]; for (1..10000) { my @array2 = @array; } say tv_interval($t0);` [download] To this: `use Time::HiRes qw(gettimeofday tv_interval); my @array = (1..100); my $t0 = [gettimeofday]; for (1..10000) { my @array2 = @array; } say tv_interval($t0);` [download]	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^3: Strange performance loss after interpolating an array and then copying to another array;
by Kc12349 (Monk) on Aug 19, 2011 at 18:13 UTC

So what causes the performance gain, though small, going from this:

use Time::HiRes qw(gettimeofday tv_interval);

my @array = (1..100);

for my $element (@array)
{
   $element .= '';
}
for my $element (@array)
{
   $element += 0;
}

my $t0 = [gettimeofday];

for (1..10000)
{
   my @array2 = @array;
}

say tv_interval($t0);
[download]

To this:

use Time::HiRes qw(gettimeofday tv_interval);

my @array = (1..100);

my $t0 = [gettimeofday];

for (1..10000)
{
   my @array2 = @array;
}

say tv_interval($t0);
[download]

[reply]
[d/l]
[select]