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CSHARP-5661: Fix UnobservedTaskException on socket connecting timeout #1742

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Merged
merged 4 commits into from
Jul 24, 2025
Merged

CSHARP-5661: Fix UnobservedTaskException on socket connecting timeout #1742

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8b69a1f
CSHARP-5661: Fix UnobservedTaskException on socket connecting timeout
sanych-sun Jul 24, 2025
5285f23
update to trigger PR build
sanych-sun Jul 24, 2025
083120e
PR
sanych-sun Jul 24, 2025
f95e743
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sanych-sun Jul 24, 2025
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6 changes: 5 additions & 1 deletion src/MongoDB.Driver/Core/Connections/TcpStreamFactory.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,11 @@ private async Task ConnectAsync(Socket socket, EndPoint endPoint, CancellationTo

if (!connectTask.IsCompleted)
{
try { socket.Dispose(); } catch { }
try
{
connectTask.IgnoreExceptions();
socket.Dispose();
} catch { }

cancellationToken.ThrowIfCancellationRequested();
throw new TimeoutException($"Timed out connecting to {endPoint}. Timeout was {_settings.ConnectTimeout}.");
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35 changes: 35 additions & 0 deletions tests/MongoDB.Driver.Tests/Core/Connections/TcpStreamFactoryTests.cs
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Expand Up @@ -185,6 +185,41 @@ public void CreateStream_should_connect_to_a_running_server_and_return_a_non_nul
stream.Should().NotBeNull();
}

[Fact]
public async Task CreateStream_should_not_produce_unobserved_exceptions_on_timeout()
{
// The idea of the test: we are trying to connect to some host/port (non-localhost) that will definitely reject the connection,
// when specifying very small timeout leads us to the TimeoutException, but also we should ensure there is no Unobserved Task Exception happening.
var subject = new TcpStreamFactory(new TcpStreamSettings(connectTimeout: TimeSpan.FromMilliseconds(1)));
var host = IPAddress.Parse("1.1.1.1");
var port = 23456;
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minor: maybe var enpdoint = new IPEndPoint(...) instead?

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Will do, leftovers from usage of TcpListener


GC.Collect();
var unobservedTaskExceptionRaised = false;
EventHandler<UnobservedTaskExceptionEventArgs> eventHandler = (s, args) =>
{
unobservedTaskExceptionRaised = true;
};

TaskScheduler.UnobservedTaskException += eventHandler;

try
{
var exception = await Record.ExceptionAsync(() => subject.CreateStreamAsync(new IPEndPoint(host, port), CancellationToken.None));
exception.Should().BeOfType<TimeoutException>();

Thread.Sleep(100);
GC.Collect();
GC.WaitForPendingFinalizers();
}
finally
{
TaskScheduler.UnobservedTaskException -= eventHandler;
}

unobservedTaskExceptionRaised.Should().BeFalse();
}

[Theory]
[ParameterAttributeData]
public void SocketConfigurator_can_be_used_to_set_keepAlive(
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