Bug #79519 [Com]: Memory leak in PHP 7.4

Edit report at https://bugs.php.net/bug.php?id=79519&edit=1 ID: 79519 Comment by: kieran at miami-nice dot co dot uk Reported by: kieran at miami-nice dot co dot uk Summary: Memory leak in PHP 7.4 Status: Open Type: Bug Package: Performance problem Operating System: Linux PHP Version: 7.4.5 Block user comment: N Private report: N New Comment: > maybe Blackfire already collects them and I can't find it Sent a message to Blackfire to see if they can provide any insight. > The PHP 7.3 memory profile states that the peak memory would be > 761 MB, but for the Text::getConsecutiveWords the allocated memory > is reported as 4060 MB. That appears to be contradictory. I think this may be something else. https://github.com/bytestream/php74-memory-leak $ php7.3 vendor/bin/phpunit --repeat 100 Time: 3.78 seconds, Memory: 396.00 MB $ php7.4 vendor/bin/phpunit --repeat 100 Time: 11.56 seconds, Memory: 734.00 MB with gc_collect_cycles in tearDown - ref; https://github.com/fzaninotto/Faker/pull/1730 $ php7.3 vendor/bin/phpunit --repeat 100 Time: 4.71 seconds, Memory: 32.00 MB $ php7.4 vendor/bin/phpunit --repeat 100 Time: 13.54 seconds, Memory: 34.00 MB If I add gc_collect_cycles to the full app, PHP 7.4 memory usage remains unchanged at 3.89GB Previous Comments: ------------------------------------------------------------------------ [2020-04-27 15:35:27] cmb@php.net The PHP 7.3 memory profile states that the peak memory would be 761 MB, but for the Text::getConsecutiveWords the allocated memory is reported as 4060 MB. That appears to be contradictory. ------------------------------------------------------------------------ [2020-04-26 19:37:50] nikic@php.net Not seeing anything obvious based on these profiles. Without a reproducer, the only suggestion I can make is to a) gather garbage collection statistics using gc_status() (maybe Blackfire already collects them and I can't find it) and b) create a memory profile using "USE_ZEND_ALLOC=0 valgrind --tool=massif php vendor/bin/phpunit" followed by "ms_print massif.*" (this will take a long time to run). This may or may not pinpoint the source of the leak. ------------------------------------------------------------------------ [2020-04-24 17:57:09] kieran at miami-nice dot co dot uk Description: ------------ I'm running the same code through PHP Unit 8.5.2 on PHP 7.3 and PHP 7.4 and there's a huge memory leak in 7.4. Several others have confirmed a similar issue in https://github.com/sebastianbergmann/phpunit/issues/3915 PHPUnit 8.5.2 - PHP 7.3.17 - Memory: 769.00 MB PHPUnit 8.5.2 - PHP 7.4.5 - Memory: 3.89 GB Both instances are running in slightly modified images of docker php. The same changes but based off php:7.3-cli-stretch and php:7.4-cli respectively. I can provide full php.ini of both which shows nothing special going on... I have generated a blackfire profile to show the issue: * PHP 7.3 - https://blackfire.io/profiles/6b973d98-014a-4dd2-8b13-f0cf5842221c/graph * PHP 7.4 - https://blackfire.io/profiles/c80f648b-a778-4b3c-8acf-00a628e1630f/graph Comparison of PHP 7.3 against 7.4 - https://blackfire.io/profiles/compare/a2dfa36c-3203-4599-959b-95d87143776a/graph -- I do note that since first running the tests (poss. PHP 7.4.4 or earlier) it was returning 4.16 GB and on 7.4.5 it's now 3.89 GB so the memory leak fixes in recent releases has helped some what... Test script: --------------- Unfortunately I cannot provide access to the code. It's a large Laravel application. I would be grateful if based on the memory profiles someone could point in the right direction to help debug the issue. Expected result: ---------------- n/a Actual result: -------------- n/a ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79519&edit=1