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Clarify ValueTask consumption guidance #12751

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Clarify ValueTask consumption guidance #12751

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4 changes: 2 additions & 2 deletions xml/System.Threading.Tasks/ValueTask.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -74,9 +74,9 @@
<format type="text/markdown"><![CDATA[

## Remarks
A `ValueTask` instance may either be awaited or converted to a <xref:System.Threading.Tasks.Task> using <xref:System.Threading.Tasks.ValueTask.AsTask*>. A `ValueTask` instance may only be awaited once, and consumers may not call <xref:System.Threading.Tasks.ValueTask.GetAwaiter> until the instance has completed. If these limitations are unacceptable, convert the `ValueTask` to a <xref:System.Threading.Tasks.Task> by calling <xref:System.Threading.Tasks.ValueTask.AsTask*>.
A `ValueTask` instance may either be awaited or converted to a <xref:System.Threading.Tasks.Task> using <xref:System.Threading.Tasks.ValueTask.AsTask*>. If the instance wraps a <xref:System.Threading.Tasks.Task> or a synchronous result, multiple awaits might succeed. However, a `ValueTask` instance can also be backed by a pooled <xref:System.Threading.Tasks.Sources.IValueTaskSource>, so consumers should treat an arbitrary `ValueTask` as single-consumption unless the provider explicitly documents support for multiple consumption. Consumers may not call <xref:System.Threading.Tasks.ValueTask.GetAwaiter> until the instance has completed. If these limitations are unacceptable, convert the `ValueTask` to a <xref:System.Threading.Tasks.Task> by calling <xref:System.Threading.Tasks.ValueTask.AsTask*>.

@gfoidl gfoidl Aug 6, 2026

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multiple awaits might succeed

(emphasis by me)

Well does this make the docs better if it just "might" succeed?
And how should a consumer know by what the VT is backed?

I'd revert this change, as it's very vague and doesn't provide any betterness -- actually it makes it worse.


The following operations should never be performed on a `ValueTask` instance:
The following operations should not be performed on a `ValueTask` instance unless the provider explicitly documents that they are supported:

@gfoidl gfoidl Aug 6, 2026

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This addition is good. But "unless ... documents it's supported" applies nearly to everything that in general should not be done and I don't think it's meaningful to append such a clause everywhere (to avoid bloat).


- Awaiting the instance multiple times.
- Calling <xref:System.Threading.Tasks.ValueTask.AsTask*> multiple times.
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4 changes: 2 additions & 2 deletions xml/System.Threading.Tasks/ValueTask`1.xml
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Expand Up @@ -90,9 +90,9 @@
<format type="text/markdown"><![CDATA[

## Remarks
A <xref:System.Threading.Tasks.ValueTask`1> instance may either be awaited or converted to a <xref:System.Threading.Tasks.Task`1> using <xref:System.Threading.Tasks.ValueTask`1.AsTask*>. A <xref:System.Threading.Tasks.ValueTask`1> instance may only be awaited once, and consumers may not read <xref:System.Threading.Tasks.ValueTask`1.Result> until the instance has completed. If these limitations are unacceptable, convert the <xref:System.Threading.Tasks.ValueTask`1> to a <xref:System.Threading.Tasks.Task`1> by calling <xref:System.Threading.Tasks.ValueTask`1.AsTask*>.
A <xref:System.Threading.Tasks.ValueTask`1> instance may either be awaited or converted to a <xref:System.Threading.Tasks.Task`1> using <xref:System.Threading.Tasks.ValueTask`1.AsTask*>. If the instance wraps a <xref:System.Threading.Tasks.Task`1> or a synchronous result, multiple awaits might succeed. However, a <xref:System.Threading.Tasks.ValueTask`1> instance can also be backed by a pooled <xref:System.Threading.Tasks.Sources.IValueTaskSource`1>, so consumers should treat an arbitrary <xref:System.Threading.Tasks.ValueTask`1> as single-consumption unless the provider explicitly documents support for multiple consumption. Consumers may not read <xref:System.Threading.Tasks.ValueTask`1.Result> until the instance has completed. If these limitations are unacceptable, convert the <xref:System.Threading.Tasks.ValueTask`1> to a <xref:System.Threading.Tasks.Task`1> by calling <xref:System.Threading.Tasks.ValueTask`1.AsTask*>.

The following operations should never be performed on a <xref:System.Threading.Tasks.ValueTask`1> instance:
The following operations should not be performed on a <xref:System.Threading.Tasks.ValueTask`1> instance unless the provider explicitly documents that they are supported:
Comment on lines +93 to +95

- Awaiting the instance multiple times.
- Calling <xref:System.Threading.Tasks.ValueTask`1.AsTask*> multiple times.
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