wasmtime / issue #12955 c-api: Async support for the comp... · git-wasmtime

Stream: git-wasmtime

Topic: wasmtime / issue #12955 c-api: Async support for the comp...

Wasmtime GitHub notifications bot (Apr 03 2026 at 18:53):

chaynabors opened issue #12955:

The core module C API has async support but the component model C API doesn't appear to. The Rust API supports this via func.call_async() so the implementation exists, just not the C bindings.

I'm hosting components from Python via wasmtime-py and need async to avoid blocking the event loop during outbound HTTP calls. As far as I can tell, what's needed is:

wasmtime_component_func_call_async

wasmtime_component_linker_instantiate_async

Async linker variants for WASI and wasi-http so host calls yield the fiber instead of blocking

Am I right in this? Is the group interested in accepting contributions for this?

Wasmtime GitHub notifications bot (Apr 03 2026 at 20:01):

alexcrichton added the wasmtime:c-api label to Issue #12955.

Wasmtime GitHub notifications bot (Apr 03 2026 at 20:01):

alexcrichton added the wasm-proposal:component-model label to Issue #12955.

Wasmtime GitHub notifications bot (Apr 03 2026 at 20:02):

alexcrichton commented on issue #12955:

Indeed this'd definitely be good to add! There's already and async.h header file for core wasm, so doing something similar for components should be relatively easily following that general scaffolding. Happy to review a PR!

Wasmtime GitHub notifications bot (Apr 03 2026 at 20:02):

alexcrichton edited a comment on issue #12955:

Indeed this'd definitely be good to add! There's already an async.h header file for core wasm, so doing something similar for components should be relatively easily following that general scaffolding. Happy to review a PR!

Wasmtime GitHub notifications bot (Apr 08 2026 at 19:12):

alexcrichton closed issue #12955:

The core module C API has async support but the component model C API doesn't appear to. The Rust API supports this via func.call_async() so the implementation exists, just not the C bindings.

I'm hosting components from Python via wasmtime-py and need async to avoid blocking the event loop during outbound HTTP calls. As far as I can tell, what's needed is:

wasmtime_component_func_call_async

wasmtime_component_linker_instantiate_async

Async linker variants for WASI and wasi-http so host calls yield the fiber instead of blocking

Am I right in this? Is the group interested in accepting contributions for this?

Last updated: Apr 12 2026 at 23:10 UTC