Stream: git-wasmtime

Topic: wasmtime / PR #12416 Refactor how concurrency support is...

Wasmtime GitHub notifications bot (Jan 23 2026 at 20:54):

alexcrichton requested wasmtime-compiler-reviewers for a review on PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 20:54):

alexcrichton requested cfallin for a review on PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 20:54):

alexcrichton opened PR #12416 from alexcrichton:concurrency-support to bytecodealliance:main:

This commit is an extension/refactor of https://github.com/bytecodealliance/wasmtime/pull/12377 and https://github.com/bytecodealliance/wasmtime/pull/12379. Notably this
decouples the runtime behavior of Wasmtime from enabled/disabled
WebAssembly proposals. This enables the wasmtime serve subcommand, for
example, to continue to disallow component-model-async by default but
continue to use *_concurrent under the hood.

Specifically a new Config::concurrency_support knob is added. This is
plumbed directly through to Tunables and takes over the preexisting
component_model_concurrency field. This field configures whether
tasks/etc are enabled at runtime for component-y things. The default
value of this configuration option is the same as cfg!(feature = "component-model-async"), and this field is required if
component-model-async wasm proposals are enabled. It's intended that
eventually this'll affect on-by-default wasm features in Wasmtime
depending if the support is compiled in.

This results in a subtle shift in behavior where component-model-async
concurrency is used by default now because the feature is turned on by
default, even though the wasm features are off-by-default. This required
adjusting a few indices expected in runtime tests due to tasks/threads
being allocated in index spaces.

Finally, this additionally denies access at runtime to
Linker::*_concurrent when concurrent support is disabled as otherwise
the various runtime data structures won't be initialized and panics will
happen.

Closes https://github.com/bytecodealliance/wasmtime/pull/12393

Wasmtime GitHub notifications bot (Jan 23 2026 at 20:54):

alexcrichton requested wasmtime-core-reviewers for a review on PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 20:54):

alexcrichton requested fitzgen for a review on PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 21:19):

alexcrichton updated PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 21:26):

alexcrichton updated PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 21:40):

alexcrichton commented on PR #12416:

cc @dicej too

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:14):

dicej submitted PR review.

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:14):

dicej created PR review comment:

            "cannot use `run_concurrent` when Config::concurrency_support disabled",

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:14):

dicej created PR review comment:

    /// [`Config::concurrency_support`] is disabled.

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:14):

dicej created PR review comment:

            "cannot use `run_concurrent` when Config::concurrency_support disabled",

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:25):

alexcrichton updated PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:25):

alexcrichton has enabled auto merge for PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 22:37):

alexcrichton added PR #12416 Refactor how concurrency support is enabled in a Store to the merge queue

Wasmtime GitHub notifications bot (Jan 23 2026 at 23:02):

alexcrichton merged PR #12416.

Wasmtime GitHub notifications bot (Jan 23 2026 at 23:02):

alexcrichton removed PR #12416 Refactor how concurrency support is enabled in a Store from the merge queue

Last updated: Jan 29 2026 at 13:25 UTC