b62fe21914
* Update memfd image construction to avoid excessively large images Previously memfd-based image construction had a hard limit of a 1GB memory image but this mean that tiny wasm modules could allocate up to 1GB of memory which became a bit excessive especially in terms of memory usage during fuzzing. To fix this the conversion to a static memory image has been updated to first do a conversion to paged memory initialization, which is sparse, followed by a second conversion to static memory initialization. The sparse construction for the paged step should make it such that the upper/lower bounds of the initialization image are easily computed, and then afterwards this limit can be checked against some heuristics to determine if we're willing to commit to building up a whole static image for that module. The heuristics have been tweaked from "must be less than 1GB" to one of two conditions must be true: * Either the total memory image size is at most twice the size of the original paged data itself. * Otherwise the memory image size must be smaller than a reasonable threshold, currently 1MB. We'll likely need to tweak this over time and it's still possible to cause a lot of extra memory consumption, but for now this should be enough to appease the fuzzers. Closes #3815 * Review comments
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.
-
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, 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 or usewasmtimeConan package - C++ - the
wasmtime-cpprepository or usewasmtime-cppConan package - 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.