Bug #68392 [NEW]: foreach memory usage increase

From: ryan dot brothers at gmail dot com Operating system: Linux PHP version: 5.6.2 Package: Performance problem Bug Type: Bug Bug description:foreach memory usage increase 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 bug report at https://bugs.php.net/bug.php?id=68392&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=68392&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=68392&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=68392&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=68392&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=68392&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=68392&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=68392&r=needscript Try newer version: https://bugs.php.net/fix.php?id=68392&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=68392&r=support Expected behavior: https://bugs.php.net/fix.php?id=68392&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=68392&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=68392&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=68392&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=68392&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=68392&r=dst IIS Stability: https://bugs.php.net/fix.php?id=68392&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=68392&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=68392&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=68392&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=68392&r=mysqlcfg