[Merged by Bors] - Nested spawns on scope #4466
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PerfPerf tests are a bit of a mixed bag currently. Faster on some tests, but slower on others. This plays out with the examples too where many_cubes is about 2% slower and many_lights is about 2% faster. Click to see perf screenshots
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LifetimesThe current PR allows the user to get a Ideally instead of passing an |
alice-i-cecile
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Done messing around with this now barring any random ideas I might get for improving the performance. |
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I did an experiment with starting tasks on demand (after |
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Added a span to record the parallel executor scope time. Screenshot is a histogram of the comparison between main and this branch with many cubes example of that span.
This confirms to me that perf on this branch vs main is workload dependant. Edit: Note the x axis is logarithmic |
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rebased on current main and reverted much of the changes to the scope executor so it again uses try_tick. reran the benches and results seem ok. Small improvements in busy systems. Small regression in 01x and 02x, but improvements in 04x. Empty systems seems like mostly noise except there's an improvement with 0 systems. A strange decent improvement to run_criteria/no that I can't explain. A small potential regression in run_criteria/yes, but it's small enough and random enough it could just be noise. edit: left is before and right is this pr. Click for benchmarksstage breakdown seems mostly similar with some speedups and slowdowns in render. This branch does seem to come out on top. many cubes and 3d_scene stage breakdown
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james7132
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Jun 14, 2022
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# Objective - Add ability to create nested spawns. This is needed for stageless. The current executor spawns tasks for each system early and runs the system by communicating through a channel. In stageless we want to spawn the task late, so that archetypes can be updated right before the task is run. The executor is run on a separate task, so this enables the scope to be passed to the spawned executor. - Fixes #4301 ## Solution - Instantiate a single threaded executor on the scope and use that instead of the LocalExecutor. This allows the scope to be Send, but still able to spawn tasks onto the main thread the scope is run on. This works because while systems can access nonsend data. The systems themselves are Send. Because of this change we lose the ability to spawn nonsend tasks on the scope, but I don't think this is being used anywhere. Users would still be able to use spawn_local on TaskPools. - Steals the lifetime tricks the `std::thread::scope` uses to allow nested spawns, but disallow scope to be passed to tasks or threads not associated with the scope. - Change the storage for the tasks to a `ConcurrentQueue`. This is to allow a &Scope to be passed for spawning instead of a &mut Scope. `ConcurrentQueue` was chosen because it was already in our dependency tree because `async_executor` depends on it. - removed the optimizations for 0 and 1 spawned tasks. It did improve those cases, but made the cases of more than 1 task slower. --- ## Changelog Add ability to nest spawns ```rust fn main() { let pool = TaskPool::new(); pool.scope(|scope| { scope.spawn(async move { // calling scope.spawn from an spawn task was not possible before scope.spawn(async move { // do something }); }); }) } ``` ## Migration Guide If you were using explicit lifetimes and Passing Scope you'll need to specify two lifetimes now. ```rust fn scoped_function<'scope>(scope: &mut Scope<'scope, ()>) {} // should become fn scoped_function<'scope>(scope: &Scope<'_, 'scope, ()>) {} ``` `scope.spawn_local` changed to `scope.spawn_on_scope` this should cover cases where you needed to run tasks on the local thread, but does not cover spawning Nonsend Futures. ## TODO * [x] think real hard about all the lifetimes * [x] add doc about what 'env and 'scope mean. * [x] manually check that the single threaded task pool still works * [x] Get updated perf numbers * [x] check and make sure all the transmutes are necessary * [x] move commented out test into a compile fail test * [x] look through the tests for scope on std and see if I should add any more tests Co-authored-by: Michael Hsu <myhsu@benjaminelectric.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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Pull request successfully merged into main. Build succeeded: |
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# Objective - Add ability to create nested spawns. This is needed for stageless. The current executor spawns tasks for each system early and runs the system by communicating through a channel. In stageless we want to spawn the task late, so that archetypes can be updated right before the task is run. The executor is run on a separate task, so this enables the scope to be passed to the spawned executor. - Fixes bevyengine#4301 ## Solution - Instantiate a single threaded executor on the scope and use that instead of the LocalExecutor. This allows the scope to be Send, but still able to spawn tasks onto the main thread the scope is run on. This works because while systems can access nonsend data. The systems themselves are Send. Because of this change we lose the ability to spawn nonsend tasks on the scope, but I don't think this is being used anywhere. Users would still be able to use spawn_local on TaskPools. - Steals the lifetime tricks the `std::thread::scope` uses to allow nested spawns, but disallow scope to be passed to tasks or threads not associated with the scope. - Change the storage for the tasks to a `ConcurrentQueue`. This is to allow a &Scope to be passed for spawning instead of a &mut Scope. `ConcurrentQueue` was chosen because it was already in our dependency tree because `async_executor` depends on it. - removed the optimizations for 0 and 1 spawned tasks. It did improve those cases, but made the cases of more than 1 task slower. --- ## Changelog Add ability to nest spawns ```rust fn main() { let pool = TaskPool::new(); pool.scope(|scope| { scope.spawn(async move { // calling scope.spawn from an spawn task was not possible before scope.spawn(async move { // do something }); }); }) } ``` ## Migration Guide If you were using explicit lifetimes and Passing Scope you'll need to specify two lifetimes now. ```rust fn scoped_function<'scope>(scope: &mut Scope<'scope, ()>) {} // should become fn scoped_function<'scope>(scope: &Scope<'_, 'scope, ()>) {} ``` `scope.spawn_local` changed to `scope.spawn_on_scope` this should cover cases where you needed to run tasks on the local thread, but does not cover spawning Nonsend Futures. ## TODO * [x] think real hard about all the lifetimes * [x] add doc about what 'env and 'scope mean. * [x] manually check that the single threaded task pool still works * [x] Get updated perf numbers * [x] check and make sure all the transmutes are necessary * [x] move commented out test into a compile fail test * [x] look through the tests for scope on std and see if I should add any more tests Co-authored-by: Michael Hsu <myhsu@benjaminelectric.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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# Objective - #4466 broke local tasks running. - Fixes #6120 ## Solution - Add system for ticking local executors on main thread into bevy_core where the tasks pools are initialized. - Add ticking local executors into thread executors ## Changelog - tick all thread local executors in task pool. ## Notes - ~~Not 100% sure about this PR. Ticking the local executor for the main thread in scope feels a little kludgy as it requires users of bevy_tasks to be calling scope periodically for those tasks to make progress.~~ took this out in favor of a system that ticks the local executors.
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# Objective - Add ability to create nested spawns. This is needed for stageless. The current executor spawns tasks for each system early and runs the system by communicating through a channel. In stageless we want to spawn the task late, so that archetypes can be updated right before the task is run. The executor is run on a separate task, so this enables the scope to be passed to the spawned executor. - Fixes bevyengine#4301 ## Solution - Instantiate a single threaded executor on the scope and use that instead of the LocalExecutor. This allows the scope to be Send, but still able to spawn tasks onto the main thread the scope is run on. This works because while systems can access nonsend data. The systems themselves are Send. Because of this change we lose the ability to spawn nonsend tasks on the scope, but I don't think this is being used anywhere. Users would still be able to use spawn_local on TaskPools. - Steals the lifetime tricks the `std::thread::scope` uses to allow nested spawns, but disallow scope to be passed to tasks or threads not associated with the scope. - Change the storage for the tasks to a `ConcurrentQueue`. This is to allow a &Scope to be passed for spawning instead of a &mut Scope. `ConcurrentQueue` was chosen because it was already in our dependency tree because `async_executor` depends on it. - removed the optimizations for 0 and 1 spawned tasks. It did improve those cases, but made the cases of more than 1 task slower. --- ## Changelog Add ability to nest spawns ```rust fn main() { let pool = TaskPool::new(); pool.scope(|scope| { scope.spawn(async move { // calling scope.spawn from an spawn task was not possible before scope.spawn(async move { // do something }); }); }) } ``` ## Migration Guide If you were using explicit lifetimes and Passing Scope you'll need to specify two lifetimes now. ```rust fn scoped_function<'scope>(scope: &mut Scope<'scope, ()>) {} // should become fn scoped_function<'scope>(scope: &Scope<'_, 'scope, ()>) {} ``` `scope.spawn_local` changed to `scope.spawn_on_scope` this should cover cases where you needed to run tasks on the local thread, but does not cover spawning Nonsend Futures. ## TODO * [x] think real hard about all the lifetimes * [x] add doc about what 'env and 'scope mean. * [x] manually check that the single threaded task pool still works * [x] Get updated perf numbers * [x] check and make sure all the transmutes are necessary * [x] move commented out test into a compile fail test * [x] look through the tests for scope on std and see if I should add any more tests Co-authored-by: Michael Hsu <myhsu@benjaminelectric.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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# Objective - bevyengine#4466 broke local tasks running. - Fixes bevyengine#6120 ## Solution - Add system for ticking local executors on main thread into bevy_core where the tasks pools are initialized. - Add ticking local executors into thread executors ## Changelog - tick all thread local executors in task pool. ## Notes - ~~Not 100% sure about this PR. Ticking the local executor for the main thread in scope feels a little kludgy as it requires users of bevy_tasks to be calling scope periodically for those tasks to make progress.~~ took this out in favor of a system that ticks the local executors.
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# Objective - bevyengine#4466 broke local tasks running. - Fixes bevyengine#6120 ## Solution - Add system for ticking local executors on main thread into bevy_core where the tasks pools are initialized. - Add ticking local executors into thread executors ## Changelog - tick all thread local executors in task pool. ## Notes - ~~Not 100% sure about this PR. Ticking the local executor for the main thread in scope feels a little kludgy as it requires users of bevy_tasks to be calling scope periodically for those tasks to make progress.~~ took this out in favor of a system that ticks the local executors.
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# Objective - Add ability to create nested spawns. This is needed for stageless. The current executor spawns tasks for each system early and runs the system by communicating through a channel. In stageless we want to spawn the task late, so that archetypes can be updated right before the task is run. The executor is run on a separate task, so this enables the scope to be passed to the spawned executor. - Fixes bevyengine#4301 ## Solution - Instantiate a single threaded executor on the scope and use that instead of the LocalExecutor. This allows the scope to be Send, but still able to spawn tasks onto the main thread the scope is run on. This works because while systems can access nonsend data. The systems themselves are Send. Because of this change we lose the ability to spawn nonsend tasks on the scope, but I don't think this is being used anywhere. Users would still be able to use spawn_local on TaskPools. - Steals the lifetime tricks the `std::thread::scope` uses to allow nested spawns, but disallow scope to be passed to tasks or threads not associated with the scope. - Change the storage for the tasks to a `ConcurrentQueue`. This is to allow a &Scope to be passed for spawning instead of a &mut Scope. `ConcurrentQueue` was chosen because it was already in our dependency tree because `async_executor` depends on it. - removed the optimizations for 0 and 1 spawned tasks. It did improve those cases, but made the cases of more than 1 task slower. --- ## Changelog Add ability to nest spawns ```rust fn main() { let pool = TaskPool::new(); pool.scope(|scope| { scope.spawn(async move { // calling scope.spawn from an spawn task was not possible before scope.spawn(async move { // do something }); }); }) } ``` ## Migration Guide If you were using explicit lifetimes and Passing Scope you'll need to specify two lifetimes now. ```rust fn scoped_function<'scope>(scope: &mut Scope<'scope, ()>) {} // should become fn scoped_function<'scope>(scope: &Scope<'_, 'scope, ()>) {} ``` `scope.spawn_local` changed to `scope.spawn_on_scope` this should cover cases where you needed to run tasks on the local thread, but does not cover spawning Nonsend Futures. ## TODO * [x] think real hard about all the lifetimes * [x] add doc about what 'env and 'scope mean. * [x] manually check that the single threaded task pool still works * [x] Get updated perf numbers * [x] check and make sure all the transmutes are necessary * [x] move commented out test into a compile fail test * [x] look through the tests for scope on std and see if I should add any more tests Co-authored-by: Michael Hsu <myhsu@benjaminelectric.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
ItsDoot
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Feb 1, 2023
# Objective - bevyengine#4466 broke local tasks running. - Fixes bevyengine#6120 ## Solution - Add system for ticking local executors on main thread into bevy_core where the tasks pools are initialized. - Add ticking local executors into thread executors ## Changelog - tick all thread local executors in task pool. ## Notes - ~~Not 100% sure about this PR. Ticking the local executor for the main thread in scope feels a little kludgy as it requires users of bevy_tasks to be calling scope periodically for those tasks to make progress.~~ took this out in favor of a system that ticks the local executors.
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Objective
Scopes #4301Solution
std::thread::scopeuses to allow nested spawns, but disallow scope to be passed to tasks or threads not associated with the scope.ConcurrentQueue. This is to allow a &Scope to be passed for spawning instead of a &mut Scope.ConcurrentQueuewas chosen because it was already in our dependency tree becauseasync_executordepends on it.Changelog
Add ability to nest spawns
Migration Guide
If you were using explicit lifetimes and Passing Scope you'll need to specify two lifetimes now.
scope.spawn_localchanged toscope.spawn_on_scopethis should cover cases where you needed to run tasks on the local thread, but does not cover spawning Nonsend Futures. Spawning of NonSend futures on scope is no longer supported.TODO