preloading shutdown frees objects before module shutdown

Description

Since cecea72a10aa6470b3426a8d2f905f5ef2fe29b3, preloading executes zend_shutdown_executor_values() early in accel_preload() directly, causing zend_objects_store_free_object_storage() to be called long before php_request_shutdown() is called, which calls php_module_shutdown() - before zend_shutdown_executor_values, normally.

Can we bring consistency here between regular request shutdown and preloading shutdown, so that the latter needs no special handling?

This change led to a crash in our extension creating an object at rinit and accessing it in rshutdown: https://github.com/DataDog/dd-trace-php/issues/1795

==77== Invalid read of size 8
==77==    at 0x583BB80: ddtrace_close_all_open_spans (span.c:504)
==77==    by 0x582CAAB: zm_deactivate_ddtrace (ddtrace.c:897)
==77==    by 0x582CAAB: zm_deactivate_ddtrace (ddtrace.c:882)
==77==    by 0x51C81B: zend_deactivate_modules (in /usr/local/sbin/php-fpm)
==77==    by 0x4B0FB3: php_request_shutdown (in /usr/local/sbin/php-fpm)
==77==    by 0x56155FF: accel_finish_startup_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x5810D13: zai_interceptor_post_startup (interceptor.c:683)
==77==    by 0x515397: zend_post_startup (in /usr/local/sbin/php-fpm)
==77==    by 0x4B18DF: php_module_startup (in /usr/local/sbin/php-fpm)
==77==  Address 0x5a63b88 is 184 bytes inside a block of size 272 free'd
==77==    at 0x48C7488: free (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==77==    by 0x5B2B4B: zend_objects_store_del (in /usr/local/sbin/php-fpm)
==77==    by 0x5ADA7F: zend_object_std_dtor (in /usr/local/sbin/php-fpm)
==77==    by 0x5B2A3B: zend_objects_store_free_object_storage (in /usr/local/sbin/php-fpm)
==77==    by 0x504A17: zend_shutdown_executor_values (in /usr/local/sbin/php-fpm)
==77==    by 0x5613F5B: accel_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x56155CB: accel_finish_startup_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x5810D13: zai_interceptor_post_startup (interceptor.c:683)
==77==    by 0x515397: zend_post_startup (in /usr/local/sbin/php-fpm)
==77==    by 0x4B18DF: php_module_startup (in /usr/local/sbin/php-fpm)
==77==  Block was alloc'd at
==77==    at 0x48C4EC0: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==77==    by 0x4E6FB3: __zend_malloc (in /usr/local/sbin/php-fpm)
==77==    by 0x4EBA4F: _ecalloc (in /usr/local/sbin/php-fpm)
==77==    by 0x5828C8B: ddtrace_span_data_create (ddtrace.c:404)
==77==    by 0x5181EB: object_init_ex (in /usr/local/sbin/php-fpm)
==77==    by 0x583B063: ddtrace_init_span (span.c:247)
==77==    by 0x583B063: ddtrace_push_root_span (span.c:284)
==77==    by 0x582AA9B: zm_activate_ddtrace (ddtrace.c:834)
==77==    by 0x51C67F: zend_activate_modules (in /usr/local/sbin/php-fpm)
==77==    by 0x4B0BAB: php_request_startup (in /usr/local/sbin/php-fpm)

(ping @nikic being commit author)

PHP Version

PHP 8.1+

Operating System

No response

首先跟踪 accel_preload() 和 zend_shutdown_executor_values()，然后将它们的顺序与 php_request_shutdown() 和 php_module_shutdown() 进行比较。使用报告中的 PHP 8.1+ preload 场景和 Valgrind trace 作为复现参考。完成的标准是：preload 关闭不再于模块关闭路径需要对象之前释放这些对象，同时不再出现报告中的无效读取。