Difference between Schedule() and ScheduleParallel()?

I know to understand this thoroughly as I optimize my code. What is the difference in how the workload is distributed amongst CPU cores?

 

In SystemBase Entities.ForEach.Schedule will force the job to run on a single thread. ScheduleParallel will run the job on parallel threads, with each thread processing one or more chunks from the query. That's my understanding at least.

 

What's the default when you don't designate either?

EDIT: Apparently in the more recent versions you have to designate Run(), Schedule(), or ScheduleParallel().

 

My understanding is run forces it to run in the main thread .. which is different from schedule since schedule is single job thread .. someone please correct me if I’m wrong.

 

Before codegen, and still currently in GameObjectConversionSystem, not designating anything (actually you can't designate anything in these contexts) is equivalent to .WithStructuralChanges().Run().

 

i saw that both worked same.
ScheduleParallel & Schedule.
only "run()" worked at mainthread

Debug.Log($"threadID {Thread.CurrentThread.ManagedThreadId}");

 

Run = single thread on main thread
Schedule = single thread on worker thread (not on main thread)
ScheduleParallel = multi threaded on worker threads

Note that synch points (job handle.complete(), other job dependancy and entity command buffers) can force the execution on main thread to finish the work.

 

This doesn't sound 100% or is subject to change 0.50 update as there is schedule, ScheduleSingle and Schedule ScheduleParallel. According to documentation, schedule and schedule parallel can be used interchangeably.

https://docs.unity3d.com/Packages/com.unity.entities@0.17/api/Unity.Entities.JobChunkExtensions.html

 

He is 100% correct. I use them.

Run = single thread on main thread
Schedule = single thread on worker thread
ScheduleParallel = multi threaded on worker threads


ScheduleSingle is the same as Schedule, it's legacy stuff.

 

It's in contrast withe documentation linked above.
Schedule<T>(T, EntityQuery, JobHandle)
Adds an IJobChunk instance to the Job scheduler queue for parallel execution. Note: This method is being replaced with use of ScheduleParallel to make non-sequential execution explicit.

 

Not the same subject. You are right for IJobChunk but above talks were about entities.foreach which state in the documentation