Concurrent Updates to Room Database Causing Inconsistent Data on UI - How to Handle?
Hey everyone, I'm running into an issue that's driving me crazy. I'm collaborating on a project where Quick question that's been bugging me - I'm relatively new to this, so bear with me... I'm experiencing issues with my Android app where concurrent updates to my Room database are causing inconsistent data to be displayed in the UI. I'm using Kotlin for development and the latest version of Room (2.4.2). The question arises when I perform multiple updates to the database from different threads without proper synchronization. For instance, I have a ViewModel that handles two different user actions which both update the same entity in the database: ```kotlin class MyViewModel(application: Application) : AndroidViewModel(application) { private val myDao: MyDao = MyDatabase.getDatabase(application).myDao() fun updateEntity1(entity: MyEntity) { viewModelScope.launch { myDao.update(entity) } } fun updateEntity2(entity: MyEntity) { viewModelScope.launch { myDao.update(entity) } } } ``` When I call `updateEntity1` and `updateEntity2` almost simultaneously, sometimes one update overwrites the other unexpectedly. I've tried adding a lock around the updates, but it doesn't seem to change the behavior: ```kotlin val lock = Any() fun updateEntity1(entity: MyEntity) { synchronized(lock) { viewModelScope.launch { myDao.update(entity) } } } ``` I also considered using transactions, but I'm unsure if that would solve the underlying scenario. The UI is supposed to reflect the latest state, but occasionally it shows outdated data. I see this log message intermittently: ``` Room: The query did not return any results. ``` What is the best practice to ensure that updates to the Room database do not lead to inconsistent data being shown in the UI? Should I be using transactions, or is there another approach that would better manage concurrent database access? For context: I'm using Kotlin on macOS. Has anyone else encountered this? For context: I'm using Kotlin on Windows. I'd really appreciate any guidance on this. I'd be grateful for any help. Has anyone else encountered this?