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Do not capture the SynchronizationContext in ConfigureAwait(ConfigureAwaitOptions) #630

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Merged
SimonCropp merged 2 commits into from
Oct 11, 2026
Merged

Do not capture the SynchronizationContext in ConfigureAwait(ConfigureAwaitOptions) #630

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67029dc
Do not capture the SynchronizationContext in ConfigureAwait(Configure…
SimonCropp Oct 11, 2026
92491a9
Make ForceYielding tests tolerate the thread pool finishing the yield…
SimonCropp Oct 11, 2026
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39 changes: 13 additions & 26 deletions src/Polyfill/Polyfill_Task.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -124,29 +124,20 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure

if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);

static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
// Task.Run always queues to the thread pool, so the current SynchronizationContext is never captured.
var inner = task;
task = Task.Run(() => inner);
}

if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);

static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
// The continuation completes successfully whatever the outcome of the antecedent.
// Reading Exception marks it as observed, without the cost of a throw and catch.
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}

return task.ConfigureAwait(
Expand All @@ -169,13 +160,9 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(

if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);

static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
// Task.Run always queues to the thread pool, so the current SynchronizationContext is never captured.
var inner = task;
task = Task.Run(() => inner);
}

return task.ConfigureAwait(
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net461/Polyfill_Task.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net462/Polyfill_Task.cs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net47/Polyfill_Task.cs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net471/Polyfill_Task.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net472/Polyfill_Task.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net48/Polyfill_Task.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
32 changes: 9 additions & 23 deletions src/Split/net481/Polyfill_Task.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,26 +95,16 @@ public static ConfiguredTaskAwaitable ConfigureAwait(this Task target, Configure
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task ForceYieldAsync(Task t)
{
await Task.Yield();
await t;
}
var inner = task;
task = Task.Run(() => inner);
}
if ((options & ConfigureAwaitOptions.SuppressThrowing) != 0)
{
task = SuppressThrowAsync(task);
static async Task SuppressThrowAsync(Task t)
{
try
{
await t;
}
catch
{
}
}
task = task.ContinueWith(
static antecedent => { _ = antecedent.Exception; },
CancellationToken.None,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Default);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand All @@ -132,12 +122,8 @@ public static ConfiguredTaskAwaitable<TResult> ConfigureAwait<TResult>(
var task = target;
if ((options & ConfigureAwaitOptions.ForceYielding) != 0)
{
task = ForceYieldAsync(task);
static async Task<TResult> ForceYieldAsync(Task<TResult> t)
{
await Task.Yield();
return await t;
}
var inner = task;
task = Task.Run(() => inner);
}
return task.ConfigureAwait(
(options & ConfigureAwaitOptions.ContinueOnCapturedContext) != 0);
Expand Down
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