Bug #68392 [Com]: foreach memory usage increase

Edit report at https://bugs.php.net/bug.php?id=68392&edit=1 ID: 68392 Comment by: xczgamer at gmail dot com Reported by: ryan dot brothers at gmail dot com Summary: foreach memory usage increase Status: Open Type: Bug Package: Performance problem Operating System: Linux PHP Version: 5.6.2 Block user comment: N Private report: N New Comment: PHP copies arrays when send to a function. Hence yes, the memory almost doubles as the entire array gets copied. If you change the following line: function test_function($rows) to: function test_function(&$rows) The memory usage will remain the same. Previous Comments: ------------------------------------------------------------------------ [2014-11-10 17:39:29] ryan dot brothers at gmail dot com Description: ------------ In the below example, the foreach in the global scope doesn't use any extra memory, but the memory usage almost doubles from doing the foreach inside test_function. Is there a reason that so much extra memory is used? I was expecting it not to use any extra memory as the foreach is done using a reference for each array element. Test script: --------------- <?php function test_function($rows) { echo memory_get_usage(true)."\n"; foreach ($rows as &$row) { } unset($row); echo memory_get_usage(true)."\n"; }; $rows = range(1, 10000); echo memory_get_usage(true)."\n"; foreach ($rows as &$row) { } unset($row); echo memory_get_usage(true)."\n"; test_function($rows); Expected result: ---------------- 1835008 1835008 1835008 1835008 Actual result: -------------- 1835008 1835008 1835008 3407872 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=68392&edit=1