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Fix a race condition which leads product to hang #1426

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Merged
merged 1 commit into from
Mar 6, 2025
Merged

Fix a race condition which leads product to hang #1426

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7 changes: 7 additions & 0 deletions src/Microsoft.VisualStudio.Threading/AsyncLazy`1.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -224,6 +224,10 @@ public Task<T> GetValueAsync(CancellationToken cancellationToken)
// to synchronously block the Main thread waiting for the result
// without leading to deadlocks.
this.joinableTask = this.jobFactory.RunAsync(valueFactory);

// this ensures that this.joinableTask must be committed before this.value
Thread.MemoryBarrier();

this.value = this.joinableTask.Task;
}
else
Expand All @@ -245,6 +249,9 @@ public Task<T> GetValueAsync(CancellationToken cancellationToken)
resumableAwaiter?.Resume();
}

// this ensures that this.joinableTask cannot be retrieved before the conditional check using this.value
Thread.MemoryBarrier();

return this.joinableTask?.JoinAsync(continueOnCapturedContext: false, cancellationToken) ?? this.value.WithCancellation(cancellationToken);
}

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