7ec073cef1
* Bring back per-thread lazy initialization Platforms Wasmtime supports may have per-thread initialization that needs to run before WebAssembly. For example Unix needs to setup a sigaltstack and macOS needs to set up mach ports. In #2757 this per-thread setup was moved out of the invocation of a wasm function, relying on the lack of Send for Store to initialize the thread at Store creation time and never worry about it later. This conflicted with [wasmtime's desired multithreading story](https://github.com/bytecodealliance/wasmtime/pull/2812) so a new [`Store::notify_switched_thread` was added](https://github.com/bytecodealliance/wasmtime/pull/2822) to explicitly indicate a Store has moved to another thread (if it unsafely did so). It turns out though that it's not always easy to determine when a `Store` moves to a new thread. For example the Go bindings for Wasmtime are generally unaware when a goroutine switches OS threads. This led to https://github.com/bytecodealliance/wasmtime-go/issues/74 where a SIGILL was left uncaught, making it appear that traps aren't working properly. This commit revisits the decision in #2757 and moves per-thread initialization back into the path of calling into WebAssembly. This is differently from before, though, where there's still only one TLS access on the path of calling into WebAssembly, unlike before where it was a separate access. This allows us to get the speed benefits of #2757 as well as the flexibility benefits of not having to explicitly move a store between threads. With this new ability this commit deletes the recently added `Store::notify_switched_thread` method since it's no longer necessary. * Fix a test compiling
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS with a small install script:
$ curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
Features
-
Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.
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Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
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Configurable. Whether you need to precompile your wasm ahead of time, generate code blazingly fast with Lightbeam, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.
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WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
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Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!
It's Wasmtime.