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[release/10.0] Fix HandleTransactionCompleted test flakiness #37520

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[release/10.0] Fix HandleTransactionCompleted test flakiness #37520

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Copilot Jan 15, 2026
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Port PR 37101 test fix
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AndriySvyryd Jan 15, 2026
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92 changes: 39 additions & 53 deletions test/EFCore.Relational.Tests/RelationalConnectionTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1085,76 +1085,62 @@ public async Task Reports_command_diagnostic_on_cancellation()
}

[ConditionalFact]
public void HandleTransactionCompleted_with_concurrent_ClearTransactions_is_thread_safe()
public async Task HandleTransactionCompleted_with_concurrent_ClearTransactions_is_thread_safe()
{
// This test verifies the fix for the race condition where HandleTransactionCompleted
// could be called on a different thread while ClearTransactions is executing.
var exceptions = new List<Exception>();

// Test with scope.Complete() before ResetState()
for (var i = 0; i < Environment.ProcessorCount; i++)
{
var connection = new FakeRelationalConnection(
CreateOptions(new FakeRelationalOptionsExtension().WithConnectionString("Database=ConcurrencyTest")));

using var scope = new TransactionScope();
var scope = new TransactionScope();
connection.Open();
scope.Complete();

var random = new Random();
var resetFirst = random.Next(0, 1) == 0;
var tasks = new Task[2];
tasks[0] = Task.Run(async () =>
// Start the reset task first, which will yield and then try to reset
var resetTask = Task.Run(async () =>
{
try
{
// Small delay to increase chance of race condition
await Task.Yield();

if (resetFirst)
{
((IResettableService)connection).ResetState();
}
else
{
scope.Complete();
}
}
catch (Exception ex)
{
lock (exceptions)
{
exceptions.Add(ex);
}
}
await Task.Yield();
// ResetState calls ClearTransactions which might race with HandleTransactionCompleted
((IResettableService)connection).ResetState();
});

tasks[1] = Task.Run(async () =>
// Dispose the scope on the main thread, which will trigger the TransactionCompleted event
// The event handler (HandleTransactionCompleted) may execute on a different thread and race
// with the ClearTransactions call in resetTask
scope.Dispose();

await resetTask;
}

// Test with ResetState() before scope.Complete()
for (var i = 0; i < Environment.ProcessorCount; i++)
{
var connection = new FakeRelationalConnection(
CreateOptions(new FakeRelationalOptionsExtension().WithConnectionString("Database=ConcurrencyTest")));

var scope = new TransactionScope();
connection.Open();

// Start the reset task first
var resetTask = Task.Run(async () =>
{
try
{
// Small delay to increase chance of race condition
await Task.Yield();

if (resetFirst)
{
scope.Complete();
}
else
{
((IResettableService)connection).ResetState();
}
}
catch (Exception ex)
{
lock (exceptions)
{
exceptions.Add(ex);
}
}
// Small delay to increase chance of race condition
await Task.Yield();

// ResetState calls ClearTransactions which might race with HandleTransactionCompleted
((IResettableService)connection).ResetState();
});

Task.WaitAll(tasks, TimeSpan.FromSeconds(10));
}
// Complete and dispose the scope, which will trigger the TransactionCompleted event
scope.Complete();
scope.Dispose();

Assert.Empty(exceptions);
await resetTask;
}
}

private static IDbContextOptions CreateOptions(params RelationalOptionsExtension[] optionsExtensions)
Expand Down