[Validator] Unnecasarry validation metadata disk reads

[umpirsky]

Symfony version(s) affected: >= 4.4

Description

Looks like this code causes disk reads, when rendering a form, this code is called, even when validation does not take place:

#0  Symfony\Component\Validator\Mapping\Loader\FileLoader->__construct() called at [vendor/symfony/symfony/src/Symfony/Component/Validator/ValidatorBuilder.php:326]
#1  Symfony\Component\Validator\ValidatorBuilder->getLoaders() called at [vendor/symfony/symfony/src/Symfony/Component/Validator/ValidatorBuilder.php:352]
#2  Symfony\Component\Validator\ValidatorBuilder->getValidator() called at [app/cache/dev/ContainerVvqCaGq/appAppKernelDevDebugContainer.php:6813]
#3  ContainerVvqCaGq\appAppKernelDevDebugContainer->getValidatorService() called at [app/cache/dev/ContainerVvqCaGq/getForm_TypeExtension_Form_ValidatorService.php:9]
#4  require(app/cache/dev/ContainerVvqCaGq/getForm_TypeExtension_Form_ValidatorService.php) called at [app/cache/dev/ContainerVvqCaGq/appAppKernelDevDebugContainer.php:2818]
#5  ContainerVvqCaGq\appAppKernelDevDebugContainer->load() called at [app/cache/dev/ContainerVvqCaGq/getForm_RegistryService.php:228]
#6  ContainerVvqCaGq\appAppKernelDevDebugContainer->{closure}() called at [vendor/symfony/symfony/src/Symfony/Component/Form/Extension/DependencyInjection/DependencyInjectionExtension.php:56]
#7  Symfony\Component\Form\Extension\DependencyInjection\DependencyInjectionExtension->getTypeExtensions() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormRegistry.php:120]
#8  Symfony\Component\Form\FormRegistry->resolveType() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormRegistry.php:94]
#9  Symfony\Component\Form\FormRegistry->getType() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormRegistry.php:127]
#10 Symfony\Component\Form\FormRegistry->resolveType() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormRegistry.php:94]
#11 Symfony\Component\Form\FormRegistry->getType() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormFactory.php:58]
#12 Symfony\Component\Form\FormFactory->createBuilder() called at [vendor/symfony/symfony/src/Symfony/Component/Form/FormFactory.php:30]
#13 Symfony\Component\Form\FormFactory->create() called at [vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Controller/ControllerTrait.php:324]

Looks like ValidatorBuilder::getLoaders() only creates loaders and constructors fire disk reads, even if FileLoader::loadClassMetadata() is not called.

Possible Solution
Check is_file(), is_readable(), stream_is_local() only when validation is executed (FileLoader::oadClassMetadata() is called).
This can be further reduced with caching, so it des not check files on each HTTP request.

[YaFou]

Hum, interesting report... This is true, the getLoaders method is called two times. However I don't know if is_file(), is_readable(), stream_is_local() functions take lot of time. Moreover, I think that PHP has a file info cache that improves the performance of these functions. Perhaps, I need more information.

[umpirsky]

Just to be clear, this issue is not about taking time or slowness. It's about disk reads that are not necessary.

[carsonbot]

Thank you for this issue.
There has not been a lot of activity here for a while. Has this been resolved?

[umpirsky]

Nope.

[nicolas-grekas]

Please check #44742
I suppose you ran some benchmark before opening this ticket?
Can you please share some data about the way this improve things?

[umpirsky]

Let me try...