Last time we saw that jobs apparently have their own Temp allocator. Still, it was unclear how many of these allocators there are. One per job job? One per thread? Just one? Today we’ll run an experiment to find the answer!
Posts Tagged native collection
Temp memory is backed by a fixed size block that’s cleared by Unity every frame. Allocations on subsequent frames return pointers to this same block. The allocated memory therefore isn’t unique. How much of a problem is this? Today we’ll do some experiments to find out!
Last week’s article came to the conclusion that allocating Temp memory from within a job was safe. This week we’ll look into that a little deeper to find out that it might not be as safe as it looks!
What do you do when a job you’re writing needs to allocate memory? You could allocate it outside of the job and pass it in, but that presents several problems. You can also allocate memory from within a job. Today we’ll look into how that works and some limitations that come along with it.
We’ve seen that Temp allocations are the fastest kind of allocations, but is this always the case? When the fixed-size block of memory they draw from runs out, are the overflow allocations just as fast? Today we’ll test to find out!
Continuing the series, today we look specifically at “overflow” allocations in the Temp allocator. We’ve seen that there’s no need to explicitly deallocate Temp memory because it all gets cleared every frame, but do we need to deallocate “overflow” allocations that didn’t fit inside the block of automatically-cleared memory? Today we’ll find out!
Last week we learned a lot about Allocator.Temp, but we left some questions open. One of them was what happens when we explicitly deallocate Temp memory. We know we don’t need to and that it’ll be deallocated at the end of the frame, but what happens when we explicitly deallocate it? Today we’ll dive in and try to find out.
When we use Allocator.Temp with a collection like NativeArray, how long does the allocation last? We’ve seen that Temp allocations are automatically disposed without the need to explicitly call Dispose, but when does the automatic dispose happen? Today we’ll test to find out!
IDisposable is becoming more and more prevalent in Unity. Previously, it was typically only used for I/O types like FileStream. Now it’s used for in-memory types like NativeArray<T> to avoid the garbage collector. Needing to call Dispose manually means we’re explicitly managing memory, just like we’d do in lower-level languages like C++. That comes with some challenges, especially with shared ownership, which we’ll deal with today.
Unity provides exactly one collection: NativeArray<T>. Compared to managed arrays in C#, these must be one-dimensional. So today we’re building a two-dimensional version of it: NativeArray<T>. We’ll add this to the NativeCollections GitHub repository for easy inclusion into any project. Read on to learn more about the collection!