Bug #74174 [Fbk->NoF]: Memory allocation problem

Edit report at https://bugs.php.net/bug.php?id=74174&edit=1 ID: 74174 Updated by: php-bugs@lists.php.net Reported by: enleury at gmail dot com Summary: Memory allocation problem -Status: Feedback +Status: No Feedback Type: Bug Package: Performance problem Operating System: Ubuntu PHP Version: 7.1.2 Assigned To: dmitry Private report: N New Comment: No feedback was provided. The bug is being suspended because we assume that you are no longer experiencing the problem. If this is not the case and you are able to provide the information that was requested earlier, please do so and change the status of the bug back to "Re-Opened". Thank you. Previous Comments: ------------------------------------------------------------------------ [2017-02-28 10:23:35] dmitry@php.net yes. I forgot, we exposed MM GC to user-level :) Actually, even this function may keep one (or maybe few) unused chunk(s) cached. Zend MM was highly tuned especially for typical real-life usage, but any suggestions for improvement are welcome. ------------------------------------------------------------------------ [2017-02-28 07:59:48] enleury at gmail dot com Thank you for clarification. Is gc_mem_caches() the only way to free up chunks? ------------------------------------------------------------------------ [2017-02-27 22:16:07] dmitry@php.net This is not a bug. If you compare peak memory usage, PHP-7 wins. PHP-7 just manages memory differently. It allocates system memory by bigger chunks (2MB) and doesn't return free chunks back to system immediately, assuming that script may request the same amount again. ------------------------------------------------------------------------ [2017-02-27 12:31:29] enleury at gmail dot com Description: ------------ Memory is not freed after return from the method. Looks like a heap defragmentation issue (https://bugs.php.net/bug.php?id=53669), but it works fine on 5.x branches. Online test script for 5.x and 7.x branches: https://3v4l.org/2OVeU#output Test script: --------------- <?php function create_docs($amount) { $documents = []; for ($i = 0; $i < $amount; $i++) { $documents[] = ['a' => $i]; } } echo memory_get_usage(true), PHP_EOL; create_docs(5000); echo memory_get_usage(true), PHP_EOL; create_docs(50000); echo memory_get_usage(true), PHP_EOL; create_docs(5000); echo memory_get_usage(true), PHP_EOL; Expected result: ---------------- 262144 524288 524288 524288 Actual result: -------------- 2097152 4194304 20971520 20971520 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=74174&edit=1