mirror of
https://github.com/bevyengine/bevy
synced 2024-11-23 13:13:49 +00:00
1abb6b0758
# Objective I found it very difficult to understand how bevy tasks work, and I concluded that the documentation should be improved for beginners like me. ## Solution These changes to the documentation were written from my beginner's perspective after some extremely helpful explanations by nil on Discord. I am not familiar enough with rustdoc yet; when looking at the source, I found the documentation at the very top of `usages.rs` helpful, but I don't know where they are rendered. They should probably be linked to from the main `bevy_tasks` README. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Mike <mike.hsu@gmail.com>
49 lines
2.2 KiB
Markdown
49 lines
2.2 KiB
Markdown
# bevy_tasks
|
|
|
|
A refreshingly simple task executor for bevy. :)
|
|
|
|
This is a simple threadpool with minimal dependencies. The main usecase is a scoped fork-join, i.e. spawning tasks from
|
|
a single thread and having that thread await the completion of those tasks. This is intended specifically for
|
|
[`bevy`][bevy] as a lighter alternative to [`rayon`][rayon] for this specific usecase. There are also utilities for
|
|
generating the tasks from a slice of data. This library is intended for games and makes no attempt to ensure fairness
|
|
or ordering of spawned tasks.
|
|
|
|
It is based on [`async-executor`][async-executor], a lightweight executor that allows the end user to manage their own threads.
|
|
`async-executor` is based on async-task, a core piece of async-std.
|
|
|
|
## Usage
|
|
|
|
In order to be able to optimize task execution in multi-threaded environments,
|
|
bevy provides three different thread pools via which tasks of different kinds can be spawned.
|
|
(The same API is used in single-threaded environments, even if execution is limited to a single thread.
|
|
This currently applies to WASM targets.)
|
|
The determining factor for what kind of work should go in each pool is latency requirements:
|
|
|
|
* For CPU-intensive work (tasks that generally spin until completion) we have a standard
|
|
[`ComputeTaskPool`] and an [`AsyncComputeTaskPool`]. Work that does not need to be completed to
|
|
present the next frame should go to the [`AsyncComputeTaskPool`].
|
|
|
|
* For IO-intensive work (tasks that spend very little time in a "woken" state) we have an
|
|
[`IoTaskPool`] whose tasks are expected to complete very quickly. Generally speaking, they should just
|
|
await receiving data from somewhere (i.e. disk) and signal other systems when the data is ready
|
|
for consumption. (likely via channels)
|
|
|
|
[bevy]: https://bevyengine.org
|
|
[rayon]: https://github.com/rayon-rs/rayon
|
|
[async-executor]: https://github.com/stjepang/async-executor
|
|
|
|
## Dependencies
|
|
|
|
A very small dependency list is a key feature of this module
|
|
|
|
```text
|
|
├── async-executor
|
|
│ ├── async-task
|
|
│ ├── concurrent-queue
|
|
│ │ └── cache-padded
|
|
│ └── fastrand
|
|
├── num_cpus
|
|
│ └── libc
|
|
├── parking
|
|
└── futures-lite
|
|
```
|