Best Multithreading Guide Unreal

Summary:

  1. Why Multithreading?
  • Imagine trying to sample every dish at a huge buffet but you can only use one plate at a time. That’s your game without multithreading. With it, you can grab multiple plates and tackle that buffet efficiently.
  1. Unreal’s Multithreading Tools:
  • FRunnable: It’s like having an extra chef in the kitchen. You set up a class, give it tasks, and it runs them in the background.
  • Task Graph System: Unreal’s way of organizing tasks to run at the same time without messing up. It’s the backbone of managing multiple tasks efficiently.
  • Async Tasks: Quick way to do something like fetching data without stopping the main game. Imagine sending a quick text while cooking.
  • ParallelFor: This speeds up loops by doing iterations at the same time. Like chopping vegetables with several knives at once.
  1. Multithreading Beyond Unreal:
  • ECS (Entity Component Systems): A modern approach that separates data and logic for better performance with multithreading.
  • Job Systems: Like Unity’s system, it lets you define jobs for concurrent running, making your game’s backend work like a well-oiled machine.
  1. Locking vs. Lock-Free Synchronization:
  • Locking: It’s like a puppy guarding its toys. Only one thread can access a variable at a time, ensuring safety but possibly causing delays.
  • Lock-Free: Here, threads share resources like well-trained pups taking turns with their toys. It can improve performance but needs careful planning.
  1. Custom Wrapper Class - The Atom Class:
  • I made a custom class called Atom for safer and easier handling of shared variables across threads. It ensures that when one thread updates a variable, others can’t mess with it until it’s done, using a simple lock system.
  1. Thread Safety Issues:
  • Problems arise when multiple threads try to access the same data simultaneously, leading to race conditions, deadlocks, and other headaches. Tools like mutexes, atomics, and careful design help prevent these.
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