Fix crash on Web / Wasm when 'atomics' flag is enabled #837
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
est31
approved these changes
Feb 17, 2024
5 tasks
github-merge-queue bot
pushed a commit
to bevyengine/bevy
that referenced
this pull request
Mar 25, 2024
# Objective This gets Bevy building on Wasm when the `atomics` flag is enabled. This does not yet multithread Bevy itself, but it allows Bevy users to use a crate like `wasm_thread` to spawn their own threads and manually parallelize work. This is a first step towards resolving #4078 . Also fixes #9304. This provides a foothold so that Bevy contributors can begin to think about multithreaded Wasm's constraints and Bevy can work towards changes to get the engine itself multithreaded. Some flags need to be set on the Rust compiler when compiling for Wasm multithreading. Here's what my build script looks like, with the correct flags set, to test out Bevy examples on web: ```bash set -e RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \ cargo build --example breakout --target wasm32-unknown-unknown -Z build-std=std,panic_abort --release wasm-bindgen --out-name wasm_example \ --out-dir examples/wasm/target \ --target web target/wasm32-unknown-unknown/release/examples/breakout.wasm devserver --header Cross-Origin-Opener-Policy='same-origin' --header Cross-Origin-Embedder-Policy='require-corp' --path examples/wasm ``` A few notes: 1. `cpal` crashes immediately when the `atomics` flag is set. That is patched in RustAudio/cpal#837, but not yet in the latest crates.io release. That can be temporarily worked around by patching Cpal like so: ```toml [patch.crates-io] cpal = { git = "https://github.com/RustAudio/cpal" } ``` 2. When testing out `wasm_thread` you need to enable the `es_modules` feature. ## Solution The largest obstacle to compiling Bevy with `atomics` on web is that `wgpu` types are _not_ Send and Sync. Longer term Bevy will need an approach to handle that, but in the near term Bevy is already configured to be single-threaded on web. Therefor it is enough to wrap `wgpu` types in a `send_wrapper::SendWrapper` that _is_ Send / Sync, but panics if accessed off the `wgpu` thread. --- ## Changelog - `wgpu` types that are not `Send` are wrapped in `send_wrapper::SendWrapper` on Wasm + 'atomics' - CommandBuffers are not generated in parallel on Wasm + 'atomics' ## Questions - Bevy should probably add CI checks to make sure this doesn't regress. Should that go in this PR or a separate PR? **Edit:** Added checks to build Wasm with atomics --------- Co-authored-by: François <[email protected]> Co-authored-by: Alice Cecile <[email protected]> Co-authored-by: daxpedda <[email protected]> Co-authored-by: François <[email protected]>
github-merge-queue bot
pushed a commit
to bevyengine/bevy
that referenced
this pull request
Mar 25, 2024
# Objective This gets Bevy building on Wasm when the `atomics` flag is enabled. This does not yet multithread Bevy itself, but it allows Bevy users to use a crate like `wasm_thread` to spawn their own threads and manually parallelize work. This is a first step towards resolving #4078 . Also fixes #9304. This provides a foothold so that Bevy contributors can begin to think about multithreaded Wasm's constraints and Bevy can work towards changes to get the engine itself multithreaded. Some flags need to be set on the Rust compiler when compiling for Wasm multithreading. Here's what my build script looks like, with the correct flags set, to test out Bevy examples on web: ```bash set -e RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \ cargo build --example breakout --target wasm32-unknown-unknown -Z build-std=std,panic_abort --release wasm-bindgen --out-name wasm_example \ --out-dir examples/wasm/target \ --target web target/wasm32-unknown-unknown/release/examples/breakout.wasm devserver --header Cross-Origin-Opener-Policy='same-origin' --header Cross-Origin-Embedder-Policy='require-corp' --path examples/wasm ``` A few notes: 1. `cpal` crashes immediately when the `atomics` flag is set. That is patched in RustAudio/cpal#837, but not yet in the latest crates.io release. That can be temporarily worked around by patching Cpal like so: ```toml [patch.crates-io] cpal = { git = "https://github.com/RustAudio/cpal" } ``` 2. When testing out `wasm_thread` you need to enable the `es_modules` feature. ## Solution The largest obstacle to compiling Bevy with `atomics` on web is that `wgpu` types are _not_ Send and Sync. Longer term Bevy will need an approach to handle that, but in the near term Bevy is already configured to be single-threaded on web. Therefor it is enough to wrap `wgpu` types in a `send_wrapper::SendWrapper` that _is_ Send / Sync, but panics if accessed off the `wgpu` thread. --- ## Changelog - `wgpu` types that are not `Send` are wrapped in `send_wrapper::SendWrapper` on Wasm + 'atomics' - CommandBuffers are not generated in parallel on Wasm + 'atomics' ## Questions - Bevy should probably add CI checks to make sure this doesn't regress. Should that go in this PR or a separate PR? **Edit:** Added checks to build Wasm with atomics --------- Co-authored-by: François <[email protected]> Co-authored-by: Alice Cecile <[email protected]> Co-authored-by: daxpedda <[email protected]> Co-authored-by: François <[email protected]>
github-merge-queue bot
pushed a commit
to bevyengine/bevy
that referenced
this pull request
Mar 25, 2024
# Objective This gets Bevy building on Wasm when the `atomics` flag is enabled. This does not yet multithread Bevy itself, but it allows Bevy users to use a crate like `wasm_thread` to spawn their own threads and manually parallelize work. This is a first step towards resolving #4078 . Also fixes #9304. This provides a foothold so that Bevy contributors can begin to think about multithreaded Wasm's constraints and Bevy can work towards changes to get the engine itself multithreaded. Some flags need to be set on the Rust compiler when compiling for Wasm multithreading. Here's what my build script looks like, with the correct flags set, to test out Bevy examples on web: ```bash set -e RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \ cargo build --example breakout --target wasm32-unknown-unknown -Z build-std=std,panic_abort --release wasm-bindgen --out-name wasm_example \ --out-dir examples/wasm/target \ --target web target/wasm32-unknown-unknown/release/examples/breakout.wasm devserver --header Cross-Origin-Opener-Policy='same-origin' --header Cross-Origin-Embedder-Policy='require-corp' --path examples/wasm ``` A few notes: 1. `cpal` crashes immediately when the `atomics` flag is set. That is patched in RustAudio/cpal#837, but not yet in the latest crates.io release. That can be temporarily worked around by patching Cpal like so: ```toml [patch.crates-io] cpal = { git = "https://github.com/RustAudio/cpal" } ``` 2. When testing out `wasm_thread` you need to enable the `es_modules` feature. ## Solution The largest obstacle to compiling Bevy with `atomics` on web is that `wgpu` types are _not_ Send and Sync. Longer term Bevy will need an approach to handle that, but in the near term Bevy is already configured to be single-threaded on web. Therefor it is enough to wrap `wgpu` types in a `send_wrapper::SendWrapper` that _is_ Send / Sync, but panics if accessed off the `wgpu` thread. --- ## Changelog - `wgpu` types that are not `Send` are wrapped in `send_wrapper::SendWrapper` on Wasm + 'atomics' - CommandBuffers are not generated in parallel on Wasm + 'atomics' ## Questions - Bevy should probably add CI checks to make sure this doesn't regress. Should that go in this PR or a separate PR? **Edit:** Added checks to build Wasm with atomics --------- Co-authored-by: François <[email protected]> Co-authored-by: Alice Cecile <[email protected]> Co-authored-by: daxpedda <[email protected]> Co-authored-by: François <[email protected]>
github-merge-queue bot
pushed a commit
to bevyengine/bevy
that referenced
this pull request
Mar 25, 2024
# Objective This gets Bevy building on Wasm when the `atomics` flag is enabled. This does not yet multithread Bevy itself, but it allows Bevy users to use a crate like `wasm_thread` to spawn their own threads and manually parallelize work. This is a first step towards resolving #4078 . Also fixes #9304. This provides a foothold so that Bevy contributors can begin to think about multithreaded Wasm's constraints and Bevy can work towards changes to get the engine itself multithreaded. Some flags need to be set on the Rust compiler when compiling for Wasm multithreading. Here's what my build script looks like, with the correct flags set, to test out Bevy examples on web: ```bash set -e RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \ cargo build --example breakout --target wasm32-unknown-unknown -Z build-std=std,panic_abort --release wasm-bindgen --out-name wasm_example \ --out-dir examples/wasm/target \ --target web target/wasm32-unknown-unknown/release/examples/breakout.wasm devserver --header Cross-Origin-Opener-Policy='same-origin' --header Cross-Origin-Embedder-Policy='require-corp' --path examples/wasm ``` A few notes: 1. `cpal` crashes immediately when the `atomics` flag is set. That is patched in RustAudio/cpal#837, but not yet in the latest crates.io release. That can be temporarily worked around by patching Cpal like so: ```toml [patch.crates-io] cpal = { git = "https://github.com/RustAudio/cpal" } ``` 2. When testing out `wasm_thread` you need to enable the `es_modules` feature. ## Solution The largest obstacle to compiling Bevy with `atomics` on web is that `wgpu` types are _not_ Send and Sync. Longer term Bevy will need an approach to handle that, but in the near term Bevy is already configured to be single-threaded on web. Therefor it is enough to wrap `wgpu` types in a `send_wrapper::SendWrapper` that _is_ Send / Sync, but panics if accessed off the `wgpu` thread. --- ## Changelog - `wgpu` types that are not `Send` are wrapped in `send_wrapper::SendWrapper` on Wasm + 'atomics' - CommandBuffers are not generated in parallel on Wasm + 'atomics' ## Questions - Bevy should probably add CI checks to make sure this doesn't regress. Should that go in this PR or a separate PR? **Edit:** Added checks to build Wasm with atomics --------- Co-authored-by: François <[email protected]> Co-authored-by: Alice Cecile <[email protected]> Co-authored-by: daxpedda <[email protected]> Co-authored-by: François <[email protected]>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
As the title says this pull request is a minimal change to fix a crash that occurs within
cpalon the Wasm target when the 'atomics' flag is enabled. This allowscpalto be used with multithreaded Wasm / Rust applications.This change is a small change adapted from this other, significantly larger, pull request: #774.