Bug #79572 [Com]: The builtin autoloader function spl_autoload() does not use opcache

Edit report at https://bugs.php.net/bug.php?id=79572&edit=1 ID: 79572 Comment by: bugreports at gmail dot com Reported by: czirkos dot zoltan at gmail dot com Summary: The builtin autoloader function spl_autoload() does not use opcache Status: Open Type: Bug Package: SPL related Operating System: Linux 4.15.0-99-generic PHP Version: 7.2.30 Block user comment: N Private report: N New Comment: > Maybe we should deprecate this functionality for PHP 8 > Even if you don't want to use a composer autoloader > a manual implementation is 3 lines of code why can't it just do the same as include / require like spl_autoload_register() registered functions behind the scenes? i mean why is tehre more than one code path loading / caching php scripts at all in the engine? Previous Comments: ------------------------------------------------------------------------ [2020-05-07 18:02:41] czirkos dot zoltan at gmail dot com Yes, deprecating can also solve this problem. Currently I use this instead: spl_autoload_register(function($class) { @include __DIR__ . "/" . strtr($class, "\\", DIRECTORY_SEPARATOR) . ".class.php"; }); Exactly 3 lines. The documentation of spl_autoload_register could also provide something like this as an example. Of course, the semantics of that function would then change as well, as the $callable argument would become mandatory. ------------------------------------------------------------------------ [2020-05-07 17:51:13] nikic@php.net Maybe we should deprecate this functionality for PHP 8. Even if you don't want to use a composer autoloader, a manual implementation is 3 lines of code. The default spl_autoload() behavior is completely non-standard nowadays (especially the lower casing of class names). ------------------------------------------------------------------------ [2020-05-07 15:16:36] laruence@php.net spl_autoload use php_stream_open_for_zend_ex directly, it will always open the file, it should use zend_stream_open instead, anyway, I am wondering if there is any real usecases of spl_autoload in realworld (most uses own autoloader like PSR-4)? ------------------------------------------------------------------------ [2020-05-07 14:14:32] czirkos dot zoltan at gmail dot com Description: ------------ PHP 7.2.30-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: Apr 19 2020 07:50:50) ( NTS ) When the builtin autoloader loads a class, it will not use opcache. It will always look for the file in the filesystem, regardless of its status. This causes performance degradation in a web server setting (eg. fpm). I reproduced the problem in the cli sapi for easy testing, test results and example files are below. Even though using opcache for cli is not realistic, I simulated loading the class multiple times by calling spl_autoload repeatedly. Please note that the problem CAN BE REPRODUCED IN FPM by strace-ing the running fpm process as well. Example files: loadedclass.php: <?php /* just an empty file */ test_spl.php: <?php set_include_path(__DIR__); spl_autoload_extensions(".class.php"); foreach (range(1, 10000) as $i) spl_autoload('loadedclass'); test_simple.php: <?php set_include_path(__DIR__); function my_autoload($name) { include $name . ".class.php"; } foreach (range(1, 10000) as $i) my_autoload('loadedclass'); The file test_simple.php contains an autoload function which is almost equivalent to 'spl_autoload'. Note that it does NOT use include_once, but it uses the simple include command, this is important. With opcache turned OFF (opcache.enable = 0, opcache.enable_cli = 0): strace -c php test_spl.php % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 45.78 0.311463 8 40174 fstat 14.87 0.101157 10 10169 3 openat 13.46 0.091557 9 10313 mmap 12.96 0.088142 9 10151 munmap 12.15 0.082671 8 10170 close Calling spl_autoload 10000 times shows tha the file is opened 10000 times (I don't know why it is fstat'ed 40000 times). The other code produces the same results, as expected: strace -c php test_simple.php % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 45.00 0.297444 7 40174 fstat 14.95 0.098808 10 10169 3 openat 14.04 0.092786 9 10151 munmap 13.47 0.089016 9 10313 mmap 11.93 0.078883 8 10170 close However with opcache turned ON (opcache.enable = 1, opcache.enable_cli = 1): strace -c php test_spl.php % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 45.58 0.317274 8 40175 fstat 14.91 0.103765 10 10170 3 openat 13.52 0.094119 9 10315 1 mmap 12.90 0.089784 9 10152 munmap 12.12 0.084343 8 10171 close For the spl autoloader, the file is still opened 10000 times! As these are openat() and mmap() kernel calls, this means that the file is also loaded and compiled. There is no speedup in the application. However, with the hand-made autoloader, the head of the strace looks like this: strace -c php test_simple.php % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 20.44 0.002377 8 316 1 mmap 16.11 0.001873 8 230 mprotect 12.28 0.001428 8 171 3 openat 9.08 0.001056 6 172 close 8.81 0.001025 6 179 fstat Execution time is almost zero, there are no 10000 file opens and loads. The same thing happens in the fpm setting. For my application with around 500 classes loaded, Apache benchmark shows 12-13 ms / page load when I'm using the spl_autoload for loading the classes, and 9-10 ms / page load when I'm using the simple autoload function above. By stracing the php7.2-fpm worker process, I get the same results: when using spl_autoload, there are many openat() kernel calls, but when using the simple autoload function, there openat() and the fstat() calls disappear. Test script: --------------- # loadedclass.class.php # empty file # test_simple.php set_include_path(__DIR__); function my_autoload($name) { include $name . ".class.php"; } foreach (range(1, 10000) as $i) my_autoload('loadedclass'); # test_spl.php set_include_path(__DIR__); spl_autoload_extensions(".class.php"); foreach (range(1, 10000) as $i) spl_autoload('loadedclass'); ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79572&edit=1