bevy/crates/bevy_tasks/src/lib.rs
James Liu 87add5660f
Immediately poll the executor once before spawning it as a task (#11801)
# Objective
At the start of every schedule run, there's currently a guaranteed piece
of overhead as the async executor spawns the MultithreadeExecutor task
onto one of the ComputeTaskPool threads.

## Solution
Poll the executor once to immediately schedule systems without waiting
for the async executor, then spawn the task if and only if the executor
does not immediately terminate.

On a similar note, having the executor task immediately start executing
a system in the same async task might yield similar results over a
broader set of cases. However, this might be more involved, and may need
a solution like #8304.
2024-02-12 15:33:35 +00:00

63 lines
1.9 KiB
Rust

#![doc = include_str!("../README.md")]
mod slice;
pub use slice::{ParallelSlice, ParallelSliceMut};
mod task;
pub use task::Task;
#[cfg(all(not(target_arch = "wasm32"), feature = "multi-threaded"))]
mod task_pool;
#[cfg(all(not(target_arch = "wasm32"), feature = "multi-threaded"))]
pub use task_pool::{Scope, TaskPool, TaskPoolBuilder};
#[cfg(any(target_arch = "wasm32", not(feature = "multi-threaded")))]
mod single_threaded_task_pool;
#[cfg(any(target_arch = "wasm32", not(feature = "multi-threaded")))]
pub use single_threaded_task_pool::{FakeTask, Scope, TaskPool, TaskPoolBuilder, ThreadExecutor};
mod usages;
#[cfg(not(target_arch = "wasm32"))]
pub use usages::tick_global_task_pools_on_main_thread;
pub use usages::{AsyncComputeTaskPool, ComputeTaskPool, IoTaskPool};
#[cfg(all(not(target_arch = "wasm32"), feature = "multi-threaded"))]
mod thread_executor;
#[cfg(all(not(target_arch = "wasm32"), feature = "multi-threaded"))]
pub use thread_executor::{ThreadExecutor, ThreadExecutorTicker};
#[cfg(feature = "async-io")]
pub use async_io::block_on;
#[cfg(not(feature = "async-io"))]
pub use futures_lite::future::block_on;
pub use futures_lite::future::poll_once;
mod iter;
pub use iter::ParallelIterator;
pub use futures_lite;
#[allow(missing_docs)]
pub mod prelude {
#[doc(hidden)]
pub use crate::{
block_on,
iter::ParallelIterator,
slice::{ParallelSlice, ParallelSliceMut},
usages::{AsyncComputeTaskPool, ComputeTaskPool, IoTaskPool},
};
}
use std::num::NonZeroUsize;
/// Gets the logical CPU core count available to the current process.
///
/// This is identical to [`std::thread::available_parallelism`], except
/// it will return a default value of 1 if it internally errors out.
///
/// This will always return at least 1.
pub fn available_parallelism() -> usize {
std::thread::available_parallelism()
.map(NonZeroUsize::get)
.unwrap_or(1)
}