Bug #73265 [Asn]: Loading browscap.ini at startup causes high memory usage

Edit report at https://bugs.php.net/bug.php?id=73265&edit=1 ID: 73265 User updated by: spam2 at rhsoft dot net Reported by: spam2 at rhsoft dot net Summary: Loading browscap.ini at startup causes high memory usage Status: Assigned Type: Bug Package: Performance problem Operating System: Linux PHP Version: 7.0.14 Assigned To: nikic Block user comment: N Private report: N New Comment: thanks foor the feedback and especially for the patch - the numbers are damned impressive! Previous Comments: ------------------------------------------------------------------------ [2016-12-17 15:32:25] nikic@php.net Compiled patterns are cached across requests. The cache size is limited (IIRC 4k patterns). get_browser() with the current implementation and the large browscap.ini file matches significantly more than 4k patterns on each call, so you don't benefit from the caching (as patterns are displaced before they can be used again). ------------------------------------------------------------------------ [2016-12-17 14:45:54] spam2 at rhsoft dot net is the result of the prce-jit somewhere stored between requests? i still try to understand what goes up behind the scenes without the pcre-jit 3 preg_replace() and 2 preg_match() goes up from 1.22 / 0.54% runtime costs to 15% (higly optimized core-cms) and so the JIT makes a really perofrmance boost - but looking at the source i have 5 different patterns and so within the request there is hardly a reuse and only reuse within requests could explain a benefit that would also explain the dramatical memory usage of browscap but on the other hand not the drop of get_browser() within a loop instead make if faster after the first call ------------------------------------------------------------------------ [2016-12-16 19:01:57] nikic@php.net PR up at https://github.com/php/php-src/pull/2242. Quoting the performance numbers: > * According to massif, the peak memory usage of PHP drops from 85MB to 23MB. > * The startup time of PHP drops from 0.19s to 0.10s. > * The time of running the get_browser_basic.phpt test with this ini drops from 19s to 0.23s. > (!!!) ------------------------------------------------------------------------ [2016-12-16 18:31:33] nikic@php.net It is a runtime option, see pcre.jit. The PCRE JIT optimizes the case where a pattern is compiled once and used multiple times. Browscap instead uses a huge amount of patterns only once. In this case the overhead of JIT compilation is larger than the benefit during the matching of the pattern. ------------------------------------------------------------------------ [2016-12-16 17:29:31] spam2 at rhsoft dot net indeed PHP 7.1 build with "--without-pcre-jit" is faster, while fast is relative given that the test did only 10 calls - what is the purpose of the JIT then and can this not be a runtime option for the cases where it brings a benefit? <?php $loops = 10; for($count=1; $count<=$loops; $count++) { $x = get_browser('Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0'); } ?> [harry@srv-rhsoft:/scripts/php5-versus-7]$ ./test.sh PHP 5.6 real 0m5.922s user 0m5.861s sys 0m0.027s PHP 7.0 real 0m14.894s user 0m14.716s sys 0m0.079s PHP 7.1 real 0m3.335s user 0m3.285s sys 0m0.031s ------------------------------------------------------------------------ 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=73265 -- Edit this bug report at https://bugs.php.net/bug.php?id=73265&edit=1