#1146 Association is not thread-safe when lazily initializing cascadeOptions [grails/grails-data-mapping] Issue created by longwa Per discussion on Slack, this method is not thread-safe and can result in an

UnsupportedOperationException

if multiple threads cascade validation at the same time for the same entity. https://github.com/grails/grails-data-mapping/blob/ef1730a42bc515cfb96cf9175d81e344d8a08a61/grails-datastore-core/src/main/groovy/org/grails/datastore/mapping/model/types/Association.java#L225 In this case, the following error will occur:

Caused by: java.lang.UnsupportedOperationException: null
        at java.util.Collections$UnmodifiableCollection.add(Collections.java:1055)
        at org.grails.datastore.mapping.model.types.Association.buildCascadeOperations(Association.java:235)
        at org.grails.datastore.mapping.model.types.Association.getCascadeOperations(Association.java:220)
        at org.grails.datastore.mapping.model.types.Association.doesCascade(Association.java:120)
        at grails.gorm.validation.PersistentEntityValidator.cascadeToAssociativeProperty(PersistentEntityValidator.groovy:134)
        at grails.gorm.validation.PersistentEntityValidator.validate(PersistentEntityValidator.groovy:82)
        at org.grails.orm.hibernate.AbstractHibernateGormInstanceApi.save(AbstractHibernateGormInstanceApi.groovy:124)
        at org.grails.datastore.gorm.GormEntity$Trait$Helper.save(GormEntity.groovy:151)
        at org.grails.datastore.gorm.GormEntity$Trait$Helper$save$1.call(Unknown Source)

Any state on the

PersistentEntityValidator

needs to be thread-safe since the same validator instance is used for entities of the same type. In this case, there are a few options: 1. Make the

buildCascadeOptions

synchronized which would fix the problem (although it does still allow multiple initializations of the options, in this case it would be fine). 2. Per @jameskleeh making the line below a local variable would also fix the issue. https://github.com/grails/grails-data-mapping/blob/ef1730a42bc515cfb96cf9175d81e344d8a08a61/grails-datastore-core/src/main/groovy/org/grails/datastore/mapping/model/types/Association.java#L231 1. Another option (not discussed in slack) is why this is even lazily initialized in the first place. Why not just call it in the constructor so the object fully constructed before it can be used. It doesn't seem like it would be that expensive unless there's some catch-22 where the

mappedForm

can't be used until the Association is built or something along those lines. I assume there's some reason why the

cascadeOptions

are lazily initialized to begin with, but worth throwing out there. Environment Grails 3.3.8 GORM 6.1.11.BUILD-SNAPSHOT Oracle jdk1.8.0_181

TornadoFX workshop was a blast! Thank you @carlw for sending those keycaps and thank you all for the support and patience. I am hoping we will see newcomers on here soon!