[Serializer] Add a way to disable ClassDiscriminatorResolver #28537
Description
Symfony version(s) affected: 4.1.4
Description
I had a performance issue on migrating my project from Symfony3.4 to Symfony4.1.
I mainly use Serializer to serialize data (through ObjectNormalizer).
After doing several blackfire analyses, I have found that problem was due to ClassDiscrimintatorResolver (#24375) which is enable by default whereas I don't need it.
To fix the problem, I had to create a Custom ObjectNormalizer and set $this->classDiscriminatorResolver to null. Not very elegant but I had a huge boost with this modification and SF4 serializer (now 90ms, 120ms without this modification) is now faster than SF3.4 (97ms).
class ObjectNormalizer extends CoreObjectNormalizer implements CacheableSupportsMethodInterface
{
public function __construct(ClassMetadataFactoryInterface $classMetadataFactory = null, NameConverterInterface $nameConverter = null,
PropertyAccessorInterface $propertyAccessor = null, PropertyTypeExtractorInterface $propertyTypeExtractor = null, ClassDiscriminatorResolverInterface $classDiscriminatorResolver = null)
{
parent::__construct($classMetadataFactory, $nameConverter, $propertyAccessor, $propertyTypeExtractor, $classDiscriminatorResolver);
/**
* Disable classDiscriminatorResolver for ObjectNormalizer. It is initialized into
https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php#L59
*/
$this->classDiscriminatorResolver = null;
}
Possible Solution
A possible solution should be to disable classDiscriminatorResolver if framework.serialiazer.discriminator_class_mapping is not set.