I'm using the $# feature to shrink an array. After shrinking to half the size, the array seems to take a bit more memory. How is that possible? (perl 5.10 on 64-bit GNU/Linux)

use strict;
use warnings;
use feature qw(say);
use Devel::Size qw(size);

my @array = 1 .. 10_000;
say size(\@array);
$#array = 5_000;
say size(\@array);

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Output: 
80064
80216

[download]

Is there a way to shrink the array without causing it to grow (and probably be reallocated)?



UPDATE: It seems splice doesn't cause the same effect.

my @array = 1 .. 10_000;
say size(\@array);
splice @array, 5_001;
say size(\@array);

[download]

Output:

80064
80064

[download]

Furthermore, after running a few simple benchmarks, it turns out the splice method is about as fast as last index assignment, so it seems splice doesn't do unnecessary copying in void context.

In reply to Shrunk array takes more memory than original by kroach

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