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james7132james7132
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Skip empty archetypes and tables when iterating over queries (#4724)
# Objective Speed up queries that are fragmented over many empty archetypes and tables. ## Solution Add a early-out to check if the table or archetype is empty before iterating over it. This adds an extra branch for every archetype matched, but skips setting the archetype/table to the underlying state and any iteration over it. This may not be worth it for the default `Query::iter` and maybe even the `Query::for_each` implementations, but this definitely avoids scheduling unnecessary tasks in the `Query::par_for_each` case. Ideally, `matched_archetypes` should only contain archetypes where there's actually work to do, but this would add a `O(n)` flat cost to every call to `update_archetypes` that scales with the number of matched archetypes. TODO: Benchmark
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‎benches/benches/bevy_ecs/empty_archetypes.rs

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use bevy_ecs::{
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component::Component,
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prelude::*,
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schedule::{Stage, SystemStage},
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world::World,
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};
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use bevy_tasks::{ComputeTaskPool, TaskPool};
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use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion};
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criterion_group!(benches, empty_archetypes);
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criterion_main!(benches);
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#[derive(Component)]
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struct A<const N: u16>(f32);
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fn iter(
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query: Query<(
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&A<0>,
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&A<1>,
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&A<2>,
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&A<3>,
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&A<4>,
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&A<5>,
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&A<6>,
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&A<7>,
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&A<8>,
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&A<9>,
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&A<10>,
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&A<11>,
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&A<12>,
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)>,
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) {
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for comp in query.iter() {
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black_box(comp);
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}
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}
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fn for_each(
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query: Query<(
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&A<0>,
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&A<1>,
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&A<2>,
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&A<3>,
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&A<4>,
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&A<5>,
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&A<6>,
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&A<7>,
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&A<8>,
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&A<9>,
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&A<10>,
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&A<11>,
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&A<12>,
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)>,
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) {
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query.for_each(|comp| {
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black_box(comp);
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});
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}
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fn par_for_each(
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task_pool: Res<ComputeTaskPool>,
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query: Query<(
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&A<0>,
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&A<1>,
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&A<2>,
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&A<3>,
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&A<4>,
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&A<5>,
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&A<6>,
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&A<7>,
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&A<8>,
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&A<9>,
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&A<10>,
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&A<11>,
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&A<12>,
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)>,
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) {
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query.par_for_each(&*task_pool, 64, |comp| {
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black_box(comp);
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});
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}
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fn setup(parallel: bool, setup: impl FnOnce(&mut SystemStage)) -> (World, SystemStage) {
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let mut world = World::new();
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let mut stage = SystemStage::parallel();
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if parallel {
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world.insert_resource(ComputeTaskPool(TaskPool::default()));
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}
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setup(&mut stage);
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(world, stage)
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}
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/// create `count` entities with distinct archetypes
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fn add_archetypes(world: &mut World, count: u16) {
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for i in 0..count {
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let mut e = world.spawn();
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e.insert(A::<0>(1.0));
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e.insert(A::<1>(1.0));
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e.insert(A::<2>(1.0));
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e.insert(A::<3>(1.0));
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e.insert(A::<4>(1.0));
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e.insert(A::<5>(1.0));
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e.insert(A::<6>(1.0));
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e.insert(A::<7>(1.0));
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e.insert(A::<8>(1.0));
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e.insert(A::<9>(1.0));
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e.insert(A::<10>(1.0));
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e.insert(A::<11>(1.0));
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e.insert(A::<12>(1.0));
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if i & 1 << 1 != 0 {
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e.insert(A::<13>(1.0));
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}
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if i & 1 << 2 != 0 {
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e.insert(A::<14>(1.0));
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}
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if i & 1 << 3 != 0 {
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e.insert(A::<15>(1.0));
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}
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if i & 1 << 4 != 0 {
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e.insert(A::<16>(1.0));
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}
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if i & 1 << 5 != 0 {
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e.insert(A::<18>(1.0));
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}
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if i & 1 << 6 != 0 {
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e.insert(A::<19>(1.0));
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}
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if i & 1 << 7 != 0 {
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e.insert(A::<20>(1.0));
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}
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if i & 1 << 8 != 0 {
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e.insert(A::<21>(1.0));
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}
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if i & 1 << 9 != 0 {
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e.insert(A::<22>(1.0));
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}
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if i & 1 << 10 != 0 {
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e.insert(A::<23>(1.0));
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}
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if i & 1 << 11 != 0 {
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e.insert(A::<24>(1.0));
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}
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if i & 1 << 12 != 0 {
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e.insert(A::<25>(1.0));
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}
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if i & 1 << 13 != 0 {
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e.insert(A::<26>(1.0));
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}
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if i & 1 << 14 != 0 {
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e.insert(A::<27>(1.0));
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}
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if i & 1 << 15 != 0 {
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e.insert(A::<28>(1.0));
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}
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}
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}
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fn empty_archetypes(criterion: &mut Criterion) {
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let mut group = criterion.benchmark_group("empty_archetypes");
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for archetype_count in [10, 100, 500, 1000, 2000, 5000, 10000] {
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let (mut world, mut stage) = setup(true, |stage| {
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stage.add_system(iter);
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});
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add_archetypes(&mut world, archetype_count);
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world.clear_entities();
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let mut e = world.spawn();
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e.insert(A::<0>(1.0));
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e.insert(A::<1>(1.0));
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e.insert(A::<2>(1.0));
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e.insert(A::<3>(1.0));
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e.insert(A::<4>(1.0));
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e.insert(A::<5>(1.0));
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e.insert(A::<6>(1.0));
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e.insert(A::<7>(1.0));
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e.insert(A::<8>(1.0));
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e.insert(A::<9>(1.0));
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e.insert(A::<10>(1.0));
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e.insert(A::<11>(1.0));
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e.insert(A::<12>(1.0));
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stage.run(&mut world);
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group.bench_with_input(
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BenchmarkId::new("iter", archetype_count),
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&archetype_count,
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|bencher, &_| {
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bencher.iter(|| {
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stage.run(&mut world);
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})
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},
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);
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}
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for archetype_count in [10, 100, 500, 1000, 2000, 5000, 10000] {
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let (mut world, mut stage) = setup(true, |stage| {
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stage.add_system(for_each);
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});
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add_archetypes(&mut world, archetype_count);
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world.clear_entities();
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let mut e = world.spawn();
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e.insert(A::<0>(1.0));
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e.insert(A::<1>(1.0));
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e.insert(A::<2>(1.0));
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e.insert(A::<3>(1.0));
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e.insert(A::<4>(1.0));
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e.insert(A::<5>(1.0));
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e.insert(A::<6>(1.0));
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e.insert(A::<7>(1.0));
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e.insert(A::<8>(1.0));
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e.insert(A::<9>(1.0));
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e.insert(A::<10>(1.0));
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e.insert(A::<11>(1.0));
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e.insert(A::<12>(1.0));
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stage.run(&mut world);
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group.bench_with_input(
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BenchmarkId::new("for_each", archetype_count),
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&archetype_count,
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|bencher, &_| {
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bencher.iter(|| {
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stage.run(&mut world);
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})
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},
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);
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}
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for archetype_count in [10, 100, 500, 1000, 2000, 5000, 10000] {
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let (mut world, mut stage) = setup(true, |stage| {
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stage.add_system(par_for_each);
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});
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add_archetypes(&mut world, archetype_count);
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world.clear_entities();
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let mut e = world.spawn();
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e.insert(A::<0>(1.0));
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e.insert(A::<1>(1.0));
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e.insert(A::<2>(1.0));
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e.insert(A::<3>(1.0));
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e.insert(A::<4>(1.0));
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e.insert(A::<5>(1.0));
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e.insert(A::<6>(1.0));
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e.insert(A::<7>(1.0));
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e.insert(A::<8>(1.0));
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e.insert(A::<9>(1.0));
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e.insert(A::<10>(1.0));
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e.insert(A::<11>(1.0));
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e.insert(A::<12>(1.0));
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stage.run(&mut world);
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group.bench_with_input(
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BenchmarkId::new("par_for_each", archetype_count),
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&archetype_count,
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|bencher, &_| {
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bencher.iter(|| {
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stage.run(&mut world);
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})
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},
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);
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}
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}

‎crates/bevy_ecs/src/query/state.rs

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@@ -983,6 +983,10 @@ impl<Q: WorldQuery, F: ReadOnlyWorldQuery> QueryState<Q, F> {
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let tables = &world.storages().tables;
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for table_id in &self.matched_table_ids {
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let table = &tables[*table_id];
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if table.is_empty() {
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continue;
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}
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let mut offset = 0;
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while offset < table.entity_count() {
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let func = func.clone();
@@ -1030,6 +1034,10 @@ impl<Q: WorldQuery, F: ReadOnlyWorldQuery> QueryState<Q, F> {
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for archetype_id in &self.matched_archetype_ids {
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let mut offset = 0;
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let archetype = &archetypes[*archetype_id];
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if archetype.is_empty() {
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continue;
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}
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while offset < archetype.len() {
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let func = func.clone();
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let len = batch_size.min(archetype.len() - offset);

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