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SplFixedArray のベンチマークを試しているときに、いくつかの奇妙な動作に気付きました。たとえば、この小さなコード スニペットを見てみましょう...

<?php
$splFixedArray = new \SplFixedArray( 100000 );
echo number_format( memory_get_usage() ) . PHP_EOL;
$variable = 'Truffaut single-origin coffee wayfarers, church-key asymmetrical 90\'s trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PBR fingerstache Bushwick Cosby sweater. McSweeney\'s mumblecore semiotics, twee quinoa tofu +1 fingerstache pop-up. Echo Park bitters disrupt irony. Truffaut single-origin coffee wayfarers, church-key asymmetrical 90\'s trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PBR fingerstache Bushwick Cosby sweater.';
var_dump( $variable );
for( $i = 0; $i < 100000; $i++ )
{
    $splFixedArray[ $i ] = $variable;
}
echo number_format( memory_get_usage() );

どの出力...

1,032,080
string(1209) "Truffaut single-origin coffee wayfarers, church-key asymmetrical 90's trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PB"...
1,032,384

それでは、for ループの最後に単純なランダムな整数を追加しましょう...

<?php
$splFixedArray = new \SplFixedArray( 100000 );
echo number_format( memory_get_usage() ) . PHP_EOL;
$variable = 'Truffaut single-origin coffee wayfarers, church-key asymmetrical 90\'s trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PBR fingerstache Bushwick Cosby sweater. McSweeney\'s mumblecore semiotics, twee quinoa tofu +1 fingerstache pop-up. Echo Park bitters disrupt irony. Truffaut single-origin coffee wayfarers, church-key asymmetrical 90\'s trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PBR fingerstache Bushwick Cosby sweater.';
var_dump( $variable );
for( $i = 0; $i < 100000; $i++ )
{
    $splFixedArray[ $i ] = $variable . rand();
}
echo number_format( memory_get_usage() );

これは...

1,034,320
string(1209) "Truffaut single-origin coffee wayfarers, church-key asymmetrical 90's trust fund hashtag before they sold out thundercats photo booth. Godard sustainable roof party keffiyeh, Odd Future chillwave mlkshk kogi VHS leggings hoodie art party next level dreamcatcher yr. Blog american apparel aesthetic tattooed farm-to-table, stumptown viral whatever mixtape raw denim Williamsburg skateboard flexitarian actually tofu. Echo Park lomo disrupt PBR, jean shorts irony fingerstache blog kale chips. Street art iPhone PB"...
129,834,272

私が興味を持っているのは、関数呼び出しによってメモリ使用量がスタックされる理由です。反復後にメモリが解放されないのは正常ですか?

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1 に答える 1

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この動作は予期されたものです。

最初のケースでは、同じ値を複数回保存しています。これは、値の単一インスタンスとそれへの参照のバッチとして実装でき、値が特定の配列にある場合のコピーオンライト セマンティックを使用します。インデックスが変更されます。

2 番目のケースでは、多くの異なる値を格納しているため、同じ方法では処理できません。各値の内容全体にメモリを割り当てる必要があるため、2 つのケースのメモリ消費量に違いが見られます。

于 2013-07-18T19:56:18.040 に答える