Job-Safe APIs in Unity 2019.3

Today’s article continues the series by finding all the job-safe APIs in the Unity engine as of 2019.3. We’ll compare against 2019.1 to see what’s new!

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Temp Memory Reuse

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!

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Allocating Memory Within a Job: Part 2

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!

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Allocating Memory Within a Job

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.

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Are Temp Allocations Always Fast?

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!

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Deallocating Temp Memory: Part 3

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!

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Deallocating Temp Memory: Part 2

Last week we dove into the code that executes when we deallocate Allocator.Temp memory to try to find out what happens. We ended up at a dead-end and were only able to draw conclusions about what doesn’t happen when we deallocate. Today we’ll try another approach to see if we gain gain more insight into the Temp allocator.

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What Does Deallocating Temp Memory Do?

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.

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How Long Does a Temp Allocation Last?

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!

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Sharing IDisposables

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.

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