Bug #72322 [Com]: High sys CPU usage

Edit report at https://bugs.php.net/bug.php?id=72322&edit=1 ID: 72322 Comment by: pavel2000 at ngs dot ru Reported by: jai at vidyamantra dot com Summary: High sys CPU usage Status: Re-Opened Type: Bug Package: Performance problem Operating System: Centos 6.8 x64 PHP Version: 7.0.7 Block user comment: N Private report: N New Comment: Catch the same issue with high sys CPU usage. Opcache module completely disabled, only php-cli is in use when we see this issue. Sys CPU usage reduced to "normal" state after command #echo "never" >/sys/kernel/mm/transparent_hugepage/enabled OS: Debian 8, PHP packages are from Debian testing. Current kernel version is # uname -a Linux web 3.2.0-4-amd64 #1 SMP Debian 3.2.82-1 x86_64 GNU/Linux # php7.1 -v PHP 7.1.11-1 (cli) (built: Oct 27 2017 13:47:15) ( NTS ) Copyright (c) 1997-2017 The PHP Group Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies # php7.1 -m [PHP Modules] bcmath calendar Core ctype curl date dom enchant exif fileinfo filter ftp gd gearman gettext gmp hash iconv igbinary intl json libxml mbstring mcrypt memcached msgpack mysqli mysqlnd openssl pcntl pcre PDO pdo_mysql pdo_pgsql pgsql Phar posix readline Reflection session shmop SimpleXML soap sockets SPL standard sysvmsg sysvsem sysvshm tidy tokenizer wddx xml xmlreader xmlwriter xsl zip zlib [Zend Modules] Previous Comments: ------------------------------------------------------------------------ [2017-09-21 03:07:30] jai at vidyamantra dot com opcache.huge_code_pages is already 0. If we don't use high values at vm.extra_free_kbytes and vm.min_free_kbytes we face this problem. ------------------------------------------------------------------------ [2017-09-21 02:32:15] wym1 at meitu dot com set opcache.huge_code_pages = 0 , it will work fine ------------------------------------------------------------------------ [2017-01-20 09:16:02] jai at vidyamantra dot com It has been two days since when we modified following kernel values. vm.extra_free_kbytes vm.min_free_kbytes Since then, we are not facing this problem. It appears the problem is with the way how PHP7 allocates or uses memory. We were able to reproduce this problem on two entirely different and isolated production servers that had no problem with php5 but this problem started within few hours after we upgraded to PHP7. Our servers have 256GB of RAM and this issue appears when free memory is low. Clearing system buffers/cache (echo 3 > /proc/sys/vm/drop_caches) always fixes this problem but Linux gradually starts caching files from disk and free memory starts dropping. ------------------------------------------------------------------------ [2016-12-25 04:22:19] php-bugs at lists dot php dot net 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. ------------------------------------------------------------------------ [2016-12-20 07:33:31] jai at vidyamantra dot com Tested on version 7.0.10 and problem is still present. It happens more often when system memory is near full (swap still empty), for e.g. system has 256GB of RAM and this happens when about only 10GB of RAM is used. At this stage, sys time increase significantly. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=72322 -- Edit this bug report at https://bugs.php.net/bug.php?id=72322&edit=1