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Join tasks waited by JoinableTaskCollection.JoinUntilEmpty in dumpasync result #1538

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Merged
lifengl merged 4 commits into from
Feb 10, 2026
Merged

Join tasks waited by JoinableTaskCollection.JoinUntilEmpty in dumpasync result #1538

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933b811
Handle JoinUntilEmpty in dumpasync
Feb 8, 2026
c8b02c7
Fix missing thread blocking state
Feb 9, 2026
9b8f1bf
Remove unused value.
Feb 9, 2026
eba9020
Adjust logic based on Copilot feedbacks.
Feb 9, 2026
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78 changes: 65 additions & 13 deletions src/SosThreadingTools/DumpAsyncCommand.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -164,6 +164,12 @@ private static void GetAllStateMachines(ClrHeap heap, List<AsyncStateMachine> al
}
}
}

ClrObject currentObject = stateMachine.TryGetObjectField("<>4__this");
if (!currentObject.IsNull && currentObject.Type is not null && string.Equals(currentObject.Type.Name, "Microsoft.VisualStudio.Threading.JoinableTaskCollection", StringComparison.Ordinal))
{
asyncState.WaitingJoinableTasks = GetJoinableTasksFromCollection(currentObject);
}
}
}
#pragma warning disable CA1031 // Do not catch general exception types
Expand All @@ -183,6 +189,40 @@ private static void GetAllStateMachines(ClrHeap heap, List<AsyncStateMachine> al
}
}

private static List<ClrObject> GetJoinableTasksFromCollection(ClrObject joinableTaskCollection)
{
var joinableTasks = new List<ClrObject>();
ClrValueType? dependentData = joinableTaskCollection.TryGetValueClassField("dependentData");
if (dependentData is not null)
{
ClrObject childDependentNodes = dependentData.TryGetObjectField("childDependentNodes");
if (!childDependentNodes.IsNull &&
childDependentNodes.TryReadField<int>("count", out int count) &&
childDependentNodes.TryReadField<int>("freeCount", out int freeCount))
{
count -= freeCount;
if (count > 0)
{
ClrObject entries = childDependentNodes.TryGetObjectField("entries");
if (!entries.IsNull && entries.IsArray && entries.AsArray() is ClrArray entriesArray)
{
for (int i = 0; i < entriesArray.Length; i++)
{
ClrValueType? value = entriesArray.GetStructValue(i);
ClrObject key = value.TryGetObjectField("key");
if (!key.IsNull)
{
joinableTasks.Add(key);
}
}
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}
}
}
}

return joinableTasks;
}

private static void ChainStateMachinesBasedOnTaskContinuations(Dictionary<ulong, AsyncStateMachine> knownStateMachines)
{
foreach (AsyncStateMachine? stateMachine in knownStateMachines.Values)
Expand Down Expand Up @@ -285,16 +325,13 @@ private static void ChainStateMachinesBasedOnJointableTasks(List<AsyncStateMachi
try
{
ClrObject joinableTask = stateMachine.StateMachine.TryGetObjectField("<>4__this");
ClrObject wrappedTask = joinableTask.TryGetObjectField("wrappedTask");
if (!wrappedTask.IsNull)
FindWaitingTaskFromJoinableTask(joinableTask, stateMachine);

if (stateMachine.WaitingJoinableTasks is List<ClrObject> joinableTasks)
{
AsyncStateMachine? previousStateMachine = allStateMachines
.FirstOrDefault(s => s.Task.Address == wrappedTask.Address);
if (previousStateMachine is object && stateMachine != previousStateMachine)
foreach (ClrObject waitingJoinableTask in joinableTasks)
{
stateMachine.Previous = previousStateMachine;
previousStateMachine.Next = stateMachine;
previousStateMachine.DependentCount++;
FindWaitingTaskFromJoinableTask(waitingJoinableTask, stateMachine);
}
}
}
Expand All @@ -306,6 +343,22 @@ private static void ChainStateMachinesBasedOnJointableTasks(List<AsyncStateMachi
}
}
}

void FindWaitingTaskFromJoinableTask(ClrObject joinableTask, AsyncStateMachine currentStateMachine)
{
ClrObject wrappedTask = joinableTask.TryGetObjectField("wrappedTask");
if (!wrappedTask.IsNull)
{
AsyncStateMachine? previousStateMachine = allStateMachines
.FirstOrDefault(s => s.Task.Address == wrappedTask.Address);
if (previousStateMachine is object && currentStateMachine != previousStateMachine)
{
currentStateMachine.Previous ??= previousStateMachine;
previousStateMachine.Next = currentStateMachine;
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previousStateMachine.DependentCount++;
}
}
}
}

private static void MarkUIThreadDependingTasks(List<AsyncStateMachine> allStateMachines)
Expand Down Expand Up @@ -388,7 +441,7 @@ private void MarkThreadingBlockTasks(ClrHeap heap, List<AsyncStateMachine> allSt
}
}

break;
continue;
}
}
}
Expand Down Expand Up @@ -438,10 +491,7 @@ private void PrintOutStateMachines(List<AsyncStateMachine> allStateMachines)
{
bool multipleLineBlock = this.PrintAsyncStateMachineChain(node, printedMachines);
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if (multipleLineBlock)
{
Console.WriteLine(string.Empty);
}
Console.WriteLine(string.Empty);
}

// Print nodes which we didn't print because of loops.
Expand Down Expand Up @@ -573,6 +623,8 @@ public AsyncStateMachine(int state, ClrObject stateMachine, ClrObject task)

public AsyncStateMachine? AlterPrevious { get; set; }

public List<ClrObject>? WaitingJoinableTasks { get; set; }

public ulong CodeAddress { get; set; }

public override string ToString()
Expand Down
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