wasm_threads example: Fix error and improve documentation

examples/wasm_threads/Cargo.toml

@@ -8,3 +8,7 @@ console_error_panic_hook = "0.1.7"
 console_log = { version = "1.0.0", features = ["color"] }
 log = "0.4.22"
 wasm_thread = "0.3.0"
+
+# Optimize all dependencies even in debug builds:
+[profile.dev.package."*"]
+opt-level = 2

examples/wasm_threads/README.md

@@ -1,47 +1,63 @@
-# Support workers with shared memory and one wasm binary
+# Web Workers with shared memory, using only a single WASM binary
 
-This is a port of [wasm_threads `simple.rs` example](https://github.com/chemicstry/wasm_thread/tree/main?tab=readme-ov-file#simple).
+This is a port of the [wasm_threads `simple.rs` example](https://github.com/chemicstry/wasm_thread/tree/main?tab=readme-ov-file#simple).
 
 It should also work similarly with `wasm-bindgen-rayon` and other packages that use SharedArrayBuffer.
 
-An explanation of that approach is described [here](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html)
+An explanation of this approach is described [here](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html).
 
 ## Limitations
 
-It has a few considerable advantages over the `webworker*` examples, but also considerable disadvantages.
+It has some significant advantages over the `webworker*' examples, but also some significant disadvantages.
 
-For starters, this needs Cross Site Isolation (setting 2 headers), which is [required for this approach to workers](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer#security_requirements).
-We've added them in the trunk config.
+For starters, it requires cross-site isolation (setting 2 headers), which is [required for this approach to workers](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer#security_requirements).
+We've added it to the trunk config.
 
-These same headers are also required during deployment. Github pages does not allow setting headers, and alternatives such as using `<meta>` did not work in my testing, so these sites can't be deployed like that. Cloudflare Pages is a free alternative that allows setting headers that worked for me.
+These same headers are also required for deployment. Github Pages does not allow setting headers, and alternatives such as using `<meta>` did not work in my tests, so these sites can't be deployed that way. Cloudflare Pages is a free alternative that does allow headers, and it worked for me.
 
-Then it also requires nightly Rust, because [the standard library needs to be rebuild](https://github.com/RReverser/wasm-bindgen-rayon?tab=readme-ov-file#building-rust-code).
+It also requires nightly Rust, because [the standard library needs to be rebuilt](https://github.com/RReverser/wasm-bindgen-rayon?tab=readme-ov-file#building-rust-code).
 
-Some libraries might not work correctly like that, since they are written under the assumption of the historially single threaded wasm32 runtimes. `wgpu` has the `fragile-send-sync-non-atomic-wasm` flag, which if set will not work with this. Eg. `egui` sets this flag currently, though it can be removed with a manual, not well tested [patch](https://github.com/9SMTM6/egui/commit/11b00084e34c8b0ff40bac82274291dff64c26db).
+Some libraries may not work correctly in this way, as they were written assuming the historical single-threaded wasm32 runtimes. wgpu` has the `fragile-send-sync-non-atomic-wasm` flag which, if set, will not work with this. For example, `egui` currently sets this flag, although it can be removed with a manual, not well tested [patch](https://github.com/9SMTM6/egui/commit/11b00084e34c8b0ff40bac82274291dff64c26db).
 
-Additional limitations are listed [here](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html#caveats) (some of them might be solved or worked around in libraries). Specifically for `wasm_thread` limitations are explained in the comments in the source code.
+Additional restrictions are listed [here](https://rustwasm.github.io/wasm-bindgen/examples/raytrace.html#caveats) (some of which may be solved or worked around in libraries). Limitations specific to `wasm_thread' are explained in the source code comments.
 
 ## Advantages
 
-* code sharing
-  * improves dev experience
-  * also means that the WASM binary will be shared, which can in the extreme case half the size of the website.
-* shared memory between threads
-  * can be a huge performance win
+* Code sharing
+  * Improves developer experience
+  * Also means that the WASM binary is shared, which in extreme cases can be half the size of the deployed application.
+  * Avoids the [web-worker cache-invalidation issue](https://github.com/trunk-rs/trunk/issues/405)
+* Memory sharing between threads
+  * can be a huge performance gain
+
 
 ## Notes on applying this
 
 Note that this requires the [toolchain file](./rust-toolchain.toml) and the [cargo config](.cargo/config.toml).
 
 The `_headers` file and its copy in `index.html` is simply an example of how to set the headers using Cloudflare Pages.
 
-If you get errors such as
+If you receive errors such as
 
 > [Firefox] The WebAssembly.Memory object cannot be serialized. The Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy HTTP headers can be used to enable this.
 
 > [Chrome] SharedArrayBuffer transfer requires self.crossOriginIsolated.
 
-Then the headers did not set correctly. You can check the response headers on the `/` file in the network tab of the browser developer tools.
+Then the headers are not set correctly. You can check the response headers on the `/` file in the Network tab of the browser developer tools.
+
+Errors such as
+> InternalError: too much recursion
+
+Were solved in the example by enabling optimizations. It was sufficient to do this on dependencies only, with
+
+```
+# in Cargo.toml
+# Optimize all dependencies even in debug builds:
+[profile.dev.package."*"]
+opt-level = 2
+```
+
+This will slow down clean rebuilds, but should not affect rebuild speed during normal development.
 
 ## Using rust-analyzer