Bug #75091 [Com]: The memory taken from opcache.interned_strings_buffer isn't refreshed

Edit report at https://bugs.php.net/bug.php?id=75091&edit=1 ID: 75091 Comment by: kimegede at gmail dot com Reported by: j3mata at gmail dot com Summary: The memory taken from opcache.interned_strings_buffer isn't refreshed Status: Open Type: Bug Package: opcache Operating System: CentOS 6 PHP Version: 7.0.22 Block user comment: N Private report: N New Comment: Running PHP 7.0.25 (+ Zend OPcache v7.0.25) on Centos 7.4.1708 Haven't yet figured out what the issue is, but with OPCache enabled, the applications will crash, leading to "500 Internal Server Error". Earlier on, I got Segfaults: Nov 2 11:32:21 ip-172-31-27-62 kernel: php-fpm[21952]: segfault at 2f2a2020 ip 00007feb149f6faf sp 00007ffe8a547c68 error 4 Nov 2 11:32:21 ip-172-31-27-62 kernel: php-fpm[22276]: segfault at 2f2a2020 ip 00007feb149f6faf sp 00007ffe8a547c68 error 4 Nov 2 11:32:21 ip-172-31-27-62 kernel: in libc-2.17.so[7feb148ba000+1b8000] Nov 2 11:09:04 ip-172-31-27-62 kernel: traps: php-fpm[123783] general protection ip:7feb176433b1 sp:7ffe8a548cc0 error:0 in php-fpm[7feb173e1000+3e8000] Nov 2 11:09:04 ip-172-31-27-62 kernel: php-fpm[123430]: segfault at 2f2a2020 ip 00007feb149f6faf sp 00007ffe8a547c68 error 4 in libc-2.17.so[7feb148ba000+1b8000] Nov 2 11:09:04 ip-172-31-27-62 kernel: traps: php-fpm[117106] general protection ip:7feb149f6faf sp:7ffe8a547e98 error:0 in libc-2.17.so[7feb148ba000+1b8000] Previous Comments: ------------------------------------------------------------------------ [2017-08-18 10:17:53] j3mata at gmail dot com Description: ------------ Hello, I have came accross this issue after we have recieved random complains for 500ISE errors, which are solved after increasing opcache.interned_strings_buffer value. Through series of tests, it seems that the memory set for opcache.interned_strings_buffer is filled the first time the opcache cache files are created and then if the value set for opcache.interned_strings_buffer is changed, the same amount of memory is requested as the first run. Clearing up the opcache file_cache restarts the above described process. This leads to unexpected behaviour: * if the value is changed to smaller then the initial value -> most likely the site will not load and will return various errors. It seems the cached files are loaded from the opcache code, until the memory is filled ( set by the smaller value ) and just doesn't load the whole application. * if the value is changed to bigger then the initial value -> the opcache uses the same amount of memory for interned_strings_buffer as the initial run. * This is produced in this environment: * shared hosting, where the users applications are kept and loaded from /home/USER/ * opcache file_cache is stored in /home/USER/.opcache * install a application which will take more then 3MB of the interned_strings_buffer memory. Observe with opcache_get_status() the interned_strings_buffer usage ** Here I am using a default WP install, add some big plugings so it has enough modiles/classes to load and somewhere in the code to print out opcache_get_status(). * Set interned_strings_buffer to 4MB and load the application - the interned_strings_buffer memory usage would be somewhere between 3MB and 4MB. * Set interned_strings_buffer to 2MB - it should break ( most often - not able to load some class or 500ISE ). * Clear /home/USER/.opcache/ files. * Set interned_strings_buffer to 2MB and again observe its usage the same way as above - it uses all 2MB ( with a few bytes left free ). * Set interned_strings_buffer to 16MB and again observe its usage - it uses exactly the same amount of memory as the first run ~ 2MB. For the tests I was using opcache.memory_consumption with values 64/128/256. Tested on PHP versions 7.0.22 and 7.1.8. I am not sure this a bug in the opcache, but certainly doesn't seem to be expected behaviour. Regards, Ilian. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=75091&edit=1