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Fix timing race condition in AwaitAssertAsync causing premature timeouts #7976

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Aaronontheweb wants to merge 5 commits into from
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Fix timing race condition in AwaitAssertAsync causing premature timeouts #7976

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5a234b6
Fix timing race condition in AwaitAssertAsync causing premature timeouts
Aaronontheweb Dec 22, 2025
09b82d7
Merge branch 'dev' into claude-wt-StartEntitySpec.StartEntity_while_t…
Arkatufus Dec 29, 2025
181cf76
fix issues with `AwaitAssert`
Aaronontheweb Dec 29, 2025
d63e738
Merge branch 'dev' into claude-wt-StartEntitySpec.StartEntity_while_t…
Aaronontheweb Dec 29, 2025
2c177e2
Merge branch 'dev' into claude-wt-StartEntitySpec.StartEntity_while_t…
Arkatufus Jan 7, 2026
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44 changes: 31 additions & 13 deletions src/core/Akka.TestKit/TestKitBase_AwaitAssert.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,6 @@

namespace Akka.TestKit
{
/// <summary>
/// TBD
/// </summary>
public abstract partial class TestKitBase
{
/// <summary>
Expand All @@ -37,7 +34,7 @@ public abstract partial class TestKitBase
public void AwaitAssert(Action assertion, TimeSpan? duration=null, TimeSpan? interval=null, CancellationToken cancellationToken = default)
{
AwaitAssertAsync(assertion, duration, interval, cancellationToken)
.WaitAndUnwrapException();
.WaitAndUnwrapException(cancellationToken);
}

/// <inheritdoc cref="AwaitAssert(Action, TimeSpan?, TimeSpan?, CancellationToken)"/>
Expand All @@ -62,16 +59,19 @@ public async Task AwaitAssertAsync(Action assertion, TimeSpan? duration=null, Ti
}
catch(Exception)
{
var stopped = Now + t;
if (stopped >= stop)
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@Aaronontheweb Aaronontheweb Dec 29, 2025

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The problem here is that we don't get 1 last chance to test the assertion if the first attempt failed and took too long

{
Sys.Log.Warning("AwaitAssert failed, timeout [{0}] is over after [{1}] attempts and [{2}] elapsed time", max, attempts, stopped - start);
throw;
}

// Check timeout after delay to avoid check-then-act race condition
}
attempts++;
await Task.Delay(t, cancellationToken);

// Check if we've exceeded the timeout AFTER sleeping
if (Now > stop)
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@Aaronontheweb Aaronontheweb Dec 29, 2025

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Now, after the delay has been completed, even if we're overdue on time we still check one final time on exit.

{
Sys.Log.Warning("AwaitAssert failed, timeout [{0}] is over after [{1}] attempts and [{2}] elapsed time", max, attempts, Now - start);
// Re-run the assertion one final time to get the actual exception
assertion();
}

t = (stop - Now).Min(intervalValue);
}
}
Expand All @@ -96,9 +96,11 @@ public async Task AwaitAssertAsync(Func<Task> assertion, TimeSpan? duration=null
var intervalValue = interval.GetValueOrDefault(TimeSpan.FromMilliseconds(100));
if(intervalValue == Timeout.InfiniteTimeSpan) intervalValue = TimeSpan.MaxValue;
intervalValue.EnsureIsPositiveFinite("interval");
var start = Now;
var max = RemainingOrDilated(duration);
var stop = Now + max;
var t = max.Min(intervalValue);
var attempts = 0;
while(true)
{
cancellationToken.ThrowIfCancellationRequested();
Expand All @@ -109,10 +111,26 @@ public async Task AwaitAssertAsync(Func<Task> assertion, TimeSpan? duration=null
}
catch(Exception)
{
if(Now + t >= stop)
throw;
// Check timeout after delay to avoid check-then-act race condition
}
attempts++;
await Task.Delay(t, cancellationToken);

// Check if we've exceeded the timeout AFTER sleeping
if (Now > stop)
{
try
{
await assertion();
return;
}
catch (Exception ex)
{
Sys.Log.Warning(ex, "AwaitAssert failed, timeout [{0}] is over after [{1}] attempts and [{2}] elapsed time", max, attempts, Now - start);
throw;
}
}
Comment on lines 120 to 132
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@Arkatufus Arkatufus Dec 29, 2025

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My only problem is that this code logs a fail warning regardless if the extra assertion invocation failed or not.

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@Aaronontheweb Aaronontheweb Dec 29, 2025

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Yeah we should remove that

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@Aaronontheweb Aaronontheweb Dec 29, 2025

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There were some other errors with this code too, like if the final assertion succeeded we'd end up running again


t = (stop - Now).Min(intervalValue);
}
}
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