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Merged
thomhurst merged 1 commit into from
Jan 11, 2026
Merged

perf: defer allocations in event receivers and hook executors #4306

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48 changes: 22 additions & 26 deletions TUnit.Engine/Services/EventReceiverOrchestrator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -40,43 +40,37 @@ public EventReceiverOrchestrator(TUnitFrameworkLogger logger)

public void RegisterReceivers(TestContext context, CancellationToken cancellationToken)
{
var objectsToRegister = new List<object>();
List<object>? objectsToRegister = null;

foreach (var obj in context.GetEligibleEventObjects())
{
if (_initializedObjects.Contains(obj))
// Use single TryAdd operation instead of Contains + Add
if (!_initializedObjects.Add(obj))
{
continue;
}

if (_initializedObjects.Add(obj))
{
bool isFirstEventReceiver = obj is IFirstTestInTestSessionEventReceiver ||
obj is IFirstTestInAssemblyEventReceiver ||
obj is IFirstTestInClassEventReceiver;

if (isFirstEventReceiver)
{
var objType = obj.GetType();
bool isFirstEventReceiver = obj is IFirstTestInTestSessionEventReceiver ||
obj is IFirstTestInAssemblyEventReceiver ||
obj is IFirstTestInClassEventReceiver;

if (_registeredFirstEventReceiverTypes.Contains(objType))
{
continue;
}
if (isFirstEventReceiver)
{
var objType = obj.GetType();

if (_registeredFirstEventReceiverTypes.Add(objType))
{
objectsToRegister.Add(obj);
}
}
else
// Use single TryAdd operation instead of Contains + Add
if (!_registeredFirstEventReceiverTypes.Add(objType))
{
objectsToRegister.Add(obj);
continue;
}
}

// Defer list allocation until actually needed
objectsToRegister ??= [];
objectsToRegister.Add(obj);
}

if (objectsToRegister.Count > 0)
if (objectsToRegister is { Count: > 0 })
{
_registry.RegisterReceivers(objectsToRegister);
}
Expand Down Expand Up @@ -147,7 +141,8 @@ public async ValueTask<List<Exception>> InvokeTestEndEventReceiversAsync(TestCon

private async ValueTask<List<Exception>> InvokeTestEndEventReceiversCore(TestContext context, CancellationToken cancellationToken, EventReceiverStage? stage)
{
var exceptions = new List<Exception>();
// Defer exception list allocation until actually needed
List<Exception>? exceptions = null;
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@campersau campersau Jan 12, 2026

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Would be good to move this down after receivers == null check as well. This was done everywhere else


// Manual filtering and sorting instead of LINQ to avoid allocations
var eligibleObjects = context.GetEligibleEventObjects();
Expand All @@ -171,7 +166,7 @@ private async ValueTask<List<Exception>> InvokeTestEndEventReceiversCore(TestCon

if (receivers == null)
{
return exceptions;
return [];
}

// Manual sort instead of OrderBy
Expand All @@ -188,11 +183,12 @@ private async ValueTask<List<Exception>> InvokeTestEndEventReceiversCore(TestCon
catch (Exception ex)
{
await _logger.LogErrorAsync($"Error in test end event receiver: {ex.Message}");
exceptions ??= [];
exceptions.Add(ex);
}
}

return exceptions;
return exceptions ?? [];
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
Expand Down
34 changes: 23 additions & 11 deletions TUnit.Engine/Services/HookExecutor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -64,14 +64,16 @@ public async ValueTask ExecuteBeforeTestSessionHooksAsync(CancellationToken canc

public async ValueTask<List<Exception>> ExecuteAfterTestSessionHooksAsync(CancellationToken cancellationToken)
{
var exceptions = new List<Exception>();
var hooks = await _hookCollectionService.CollectAfterTestSessionHooksAsync().ConfigureAwait(false);

if (hooks.Count == 0)
{
return exceptions;
return [];
}

// Defer exception list allocation until actually needed
List<Exception>? exceptions = null;

foreach (var hook in hooks)
{
try
Expand All @@ -83,11 +85,12 @@ public async ValueTask<List<Exception>> ExecuteAfterTestSessionHooksAsync(Cancel
{
// Collect hook exceptions instead of throwing immediately
// This allows all hooks to run even if some fail
exceptions ??= [];
exceptions.Add(new AfterTestSessionException($"AfterTestSession hook failed: {ex.Message}", ex));
}
}

return exceptions;
return exceptions ?? [];
}

public async ValueTask ExecuteBeforeAssemblyHooksAsync(Assembly assembly, CancellationToken cancellationToken)
Expand Down Expand Up @@ -126,14 +129,16 @@ public async ValueTask ExecuteBeforeAssemblyHooksAsync(Assembly assembly, Cancel

public async ValueTask<List<Exception>> ExecuteAfterAssemblyHooksAsync(Assembly assembly, CancellationToken cancellationToken)
{
var exceptions = new List<Exception>();
var hooks = await _hookCollectionService.CollectAfterAssemblyHooksAsync(assembly).ConfigureAwait(false);

if (hooks.Count == 0)
{
return exceptions;
return [];
}

// Defer exception list allocation until actually needed
List<Exception>? exceptions = null;

foreach (var hook in hooks)
{
try
Expand All @@ -146,11 +151,12 @@ public async ValueTask<List<Exception>> ExecuteAfterAssemblyHooksAsync(Assembly
{
// Collect hook exceptions instead of throwing immediately
// This allows all hooks to run even if some fail
exceptions ??= [];
exceptions.Add(new AfterAssemblyException($"AfterAssembly hook failed: {ex.Message}", ex));
}
}

return exceptions;
return exceptions ?? [];
}

public async ValueTask ExecuteBeforeClassHooksAsync(
Expand Down Expand Up @@ -193,14 +199,16 @@ public async ValueTask<List<Exception>> ExecuteAfterClassHooksAsync(
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.PublicProperties | DynamicallyAccessedMemberTypes.PublicMethods)]
Type testClass, CancellationToken cancellationToken)
{
var exceptions = new List<Exception>();
var hooks = await _hookCollectionService.CollectAfterClassHooksAsync(testClass).ConfigureAwait(false);

if (hooks.Count == 0)
{
return exceptions;
return [];
}

// Defer exception list allocation until actually needed
List<Exception>? exceptions = null;

foreach (var hook in hooks)
{
try
Expand All @@ -213,11 +221,12 @@ public async ValueTask<List<Exception>> ExecuteAfterClassHooksAsync(
{
// Collect hook exceptions instead of throwing immediately
// This allows all hooks to run even if some fail
exceptions ??= [];
exceptions.Add(new AfterClassException($"AfterClass hook failed: {ex.Message}", ex));
}
}

return exceptions;
return exceptions ?? [];
}

public async ValueTask ExecuteBeforeTestHooksAsync(AbstractExecutableTest test, CancellationToken cancellationToken)
Expand Down Expand Up @@ -285,7 +294,8 @@ public async ValueTask ExecuteBeforeTestHooksAsync(AbstractExecutableTest test,

public async ValueTask<List<Exception>> ExecuteAfterTestHooksAsync(AbstractExecutableTest test, CancellationToken cancellationToken)
{
var exceptions = new List<Exception>();
// Defer exception list allocation until actually needed
List<Exception>? exceptions = null;
var testClassType = test.Metadata.TestClassType;

// Execute After(Test) hooks first (specific hooks run before global hooks for cleanup)
Expand All @@ -302,6 +312,7 @@ public async ValueTask<List<Exception>> ExecuteAfterTestHooksAsync(AbstractExecu
}
catch (Exception ex)
{
exceptions ??= [];
exceptions.Add(new AfterTestException($"After(Test) hook failed: {ex.Message}", ex));
}
}
Expand All @@ -321,12 +332,13 @@ public async ValueTask<List<Exception>> ExecuteAfterTestHooksAsync(AbstractExecu
}
catch (Exception ex)
{
exceptions ??= [];
exceptions.Add(new AfterTestException($"AfterEvery(Test) hook failed: {ex.Message}", ex));
}
}
}

return exceptions;
return exceptions ?? [];
}

public async ValueTask ExecuteBeforeTestDiscoveryHooksAsync(CancellationToken cancellationToken)
Expand Down
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