How to Disable Entities.ForEach Parallel Safety Check (two jobs writing to same component type)?

Say I have for instance:

Code (CSharp):

1. var job1Handle = Entities
2.     .WithAll<ExclusionTag>
3.     .ForEach((ref WriteToData writeToData) =>
4. {
5.     // Some work
6. }).Schedule(inputDeps);
7.  
8. var job2Handle = Entities
9.     .WithNone<ExclusionTag>
10.     .ForEach((ref WriteToData writeToData) =>
11. {
12.     // Some other work
13. }).Schedule(inputDeps);
14.  
15. return JobHandle.CombineDependencies(job1Handle, job2Handle);

Since the two jobs use the ExclusionTag component to xor the results of their queries, I know I won't try to write to the same components, but I get a safety check error when this system runs. I'm upgrading from a much earlier version of Unity.Entities that just didn't have this safety check I guess because this wasn't complaining. How can I tell it that it's okay for these to run parallel? (for now I'm just making job1Handle a dependency for job2 and returning job2Handle, but my understanding is that means this won't run parallel)

 

As a walkaround, you can do:

Code (CSharp):

1.            var WriteToDataAccess = GetComponentDataFromEntity<WriteToData>(false);
2.             var job1Handle = Entities.WithNativeDisableContainerSafetyRestriction(WriteToDataAccess).WithAll<ExclusionTag>().ForEach((Entity entity) =>
3.             {
4.                 WriteToDataAccess[entity] = new WriteToData() { Value = 1 };
5.                 // Some work
6.             }).Schedule(Dependency);
7.  
8.             var job2Handle = Entities.WithNativeDisableContainerSafetyRestriction(WriteToDataAccess).WithNone<ExclusionTag>().ForEach((Entity entity) =>
9.             {
10.                 WriteToDataAccess[entity] = new WriteToData() { Value = 1 };
11.                 // Some other work
12.             }).Schedule(Dependency);
13.  
14.             Dependency = JobHandle.CombineDependencies(job1Handle, job2Handle);

 

Interesting idea, thanks!

@joepl Thanks for confirmation that this just isn't possible atm. Please put me down for a vote to please allow this
Also fwiw, I had to use an IJobChunk in another scenario simply because we don't seem to have an equivalent for ScheduleSingle in Entities.ForEach lambdas. I'm extremely appreciating how much easier it is using Entities.ForEach over jobs (directly), so please put me down for strong votes to have these features added. Thank you!

 

This exists. If you are using SystemBase, Schedule is single-threaded and ScheduleParallel is parallel.

 

Hmmm, I'm not very familiar with SystemBase and haven't tried using it yet. My understanding of how this all comes together is probably very imperfect, but it looks like it doesn't have inputDependencies, and it seems like that would be kind of problematic for scheduling in an ideal way.

 

Instead of using an input argument and a return value, it uses a property in the class called Dependency. You use it and assign back to it for all jobs. And the lambdas will automatically do this for you if you don't specify JobHandles. It is a slick way of combining ComponentSystem and JobComponentSystem into one.

 

Awesome, thanks so much for the tip!

 

Also really good to know, thanks for the follow up!

 

Re: SystemBase: I'm trying out using that now, but it's using ForEachLambdaJobDescription instead of ForEachLambdaJobDescriptionJCS. The documentation links to the standard Entities.ForEach documentation (https://docs.unity3d.com/Packages/com.unity.entities@0.9/manual/ecs_entities_foreach.html) but the non-JCS lambda behaves different. For instance, trying to get a DynamicBuffer in the parameters of the lambda throws an error when I try to do it the same way I do for ForEachLambdaJobDescriptionJCS (`in DynamicBuffer<MyBufferElement> myParam`).

Code (CSharp):

1. void EntityQueryBuilder.ForEach(EntityQueryBuilder.F_E action)
2. The type 'Unity.Entities.DynamicBuffer<MyBufferElement>' cannot be used as type parameter 'T0' in the generic type or method 'EntityQueryBuilder.ForEach<T0>(EntityQueryBuilder.F_D<T0>)'. There is no boxing conversion from 'Unity.Entities.DynamicBuffer<MyBufferElement>' to 'Unity.Entities.IComponentData'.

 

Oh yeah entirely possible my brain just stepped out for a minute and I wrote ComponentSystem instead of SystemBase, I'll give it another try. Thanks for the link! (EDIT: Confirmed I was being dense and had descended my system from ComponentSystem not SystemBase which is why Entities.ForEach lambda params were working unexpectedly. Thanks for catching that!)

 

Also just because we kind of went off an a tangent with SystemBase, I just wanted to reiterate and clarify that I would still love to be able to use JCS to schedule parallel jobs that operate on the same components if I know they won't overlap (I wind up doing this fairly often and it results in a runtime error). Thanks for listening, @joepl