Rework ReturnValueValidator and ExecutionValidator

[YegorStepanov]

• Add ParamsSource support
• Add Arguments/ArgumentsSource support
• Fill Params/ParamsSource before GlobalSetup (fixes #2083 fixes #848)
• Await async benchmarks (previously, only GlobalSetup/GlobalCleanup were awaited)
• Call IterationSetup/IterationCleanup
• Show error for the async iteration methods

Each benchmark is run on the new instance.

ReturnValueValidator:

• Compare Task value instead task objects itself

[YegorStepanov]

Deadlock in tests. I cannot reproduce it on local machine (Windows). I ran them few times, the deadlock happens every time.

Github Actions: deadlock on Windows/Linux. MacOS is ok Azure Pipelines: deadlock on Linux. Window/MacOS is ok AppVeyor: deadlock

I need to execute a method via Reflection, await it (if the method is async: Task or ValueTask) and return result (if the Task is not void).

MethodInfo benchmarkMethod = ...
var result = benchmarkMethod.Invoke(benchmarkClassInstance, arguments); // (arguments.Any() ? arguments : null) not helped

if (TryAwaitTask(result, out var taskResult))
    result = taskResult;

// returns true if the method is async
private static bool TryAwaitTask(object task, out object result)
{
    result = null;

    if (task is null)
    {
        return false;
    }
    
    // ValueTask<T>
    var returnType = task.GetType();
    if (returnType.IsGenericType && returnType.GetGenericTypeDefinition() == typeof(ValueTask<>))
    {
        var asTaskMethod = task.GetType().GetMethod("AsTask");
        task = asTaskMethod.Invoke(task, null);
    }

    if (task is ValueTask valueTask)
        task = valueTask.AsTask();
    
    // Task or Task<T>
    if (task is Task t)
    {
        if (TryGetTaskResult(t, out var taskResult))
            result = taskResult;

        return true;
    }

    return false;
}

// https://stackoverflow.com/a/52500763
private static bool TryGetTaskResult(Task task, out object result)
{
    result = null;

    var voidTaskType = typeof(Task<>).MakeGenericType(Type.GetType("System.Threading.Tasks.VoidTaskResult"));
    if (voidTaskType.IsInstanceOfType(task))
    {
        task.GetAwaiter().GetResult();
        return false;
    }

    var property = task.GetType().GetProperty("Result", BindingFlags.Public | BindingFlags.Instance);
    if (property is null)
    {
        return false;
    }

    result = property.GetValue(task);
    return true;
}

The deadlock occurs on executing these async methods in parallel

public class AsyncGenericValueTaskGlobalSetup
{
    [GlobalSetup]
    public async ValueTask<int> GlobalSetup()
    {
        await Task.Delay(1);
        return 42;
    }
}

public class AsyncSetupIsSupportedClass
{
    [Benchmark]
    public async Task<int> Foo()
    {
        await Task.Delay(1);
        return 1;
    }
}

No one else uses the task.

valueTask.AsTask() creates a new normal task? valueTask.AsTask().Result is a correct way to sync wait?

@stephentoub, only You know what's going on here. Maybe it's a BLC bug?

[timcassell]

I don't see anything wrong with that code. But I just updated my AwaitHelper in #2108 to work for multiple threads, and I wonder if you tried the same thing if it would make a difference.

private static bool TryAwaitTask(object task, out object result)
{
    result = null;
    if (task is null)
    {
        return false;
    }
    var getResultMethod = AwaitHelper.GetGetResultMethod(task.GetType());
    if (getResultMethod is null)
    {
        return false;
    }
    result = getResultMethod.Invoke(null, new[] { task });
    return true;
    // Or
    // return getResultMethod.ReturnType != typeof(void);
}

[YegorStepanov]

Hey, Tim! I tried your solution, deadlock still exists.

Changing ValueTask to Task doesn't help. I tried to lock invocation, but it didn't help. Although a new object is created on each ExecutionValidatorBase.Validate call. And each test method is isolated.

The deadlock occurs on execution ExecutionValidatorTests and ReturnValueValidatorTests in parallel. If I remove all async methods from any of these files - deadlock is done.

I deleted all other tests except these and all sync methods in these tests - the situation is the same.

I think the problem is due to the version of .NET Framework (net461) or with XUnit.

[YegorStepanov]

What I did...

Summary:

• Try Tim's multithreaded AwaitHelper.GetGetResultMethod()
• Change ValueTask to Task
• Add lock to both validators and to their base class
• Bumped .Net Framework from 4.61/4.62 to 4.8 in solution
• Bumped .Net Core from netcoreapp2.1/net6.0 to 6.0 in solution
• Updated xUnit packages
• Updated Microsoft.NET.Test.Sdk, Microsoft.NETCore.Platforms, Microsoft.NETFramework.ReferenceAssemblies
• Updated VM Ubuntu-20.04 to Ubuntu-latest
• Updated VM Windows-20.04 to Windows-latest

Still deadlock on Windows/Linux

What works:

• Remove all "async" tests from any of these classes
• Add [Collection("Disable parallelism")] to both test classes to disable parallelism.

I hope it's a xUnit issue. I will send it to them.

[timcassell]

I'm curious why the deadlock only happens with your changes, and not in the existing tests that do the same blocking wait (just without reading the result). By deduction, it must be some other change causing it, no?

[YegorStepanov]

Currently, these validators don't await async methods. They simple call Invoke:

MethodInfo benchmarkMethod = ...;
benchmarkMethod.Invoke(null);

Yep, it's a xUnit bug, msTest and nUnit are completed successfully.

I'll send a bug report in a few hours.

[YegorStepanov]

The bug is unlikely to be fixed anytime soon.

[timcassell]

You added validation here to make sure IterationSetup/Cleanup are not async. I actually added async support for them in #2111, and this seems likely to get merged first, so I'll have to remember to update the validator there.

[timcassell]

I wonder if that xUnit bug is the cause of the AllSetupAndCleanupTest flakiness. :thinking:

[YegorStepanov]

You added validation here to make sure IterationSetup/Cleanup are not async. I actually added async support for them in https://github.com/dotnet/BenchmarkDotNet/pull/2111, and this seems likely to get merged first, so I'll have to remember to update the validator there.

Okay, I'll keep an eye on it too. Also you can ping me because I want to move more checks from BenchmarkConverter to the validators and remove duplicate checks from these PR's classes.

I hope your PRs will be accepted before the Unity moves to .NET Core. Just two years left to wait 😭

[YegorStepanov]

I wonder if that xUnit bug is the cause of the AllSetupAndCleanupTest flakiness. 🤔

I didn't even think why some tests are flakiness. These tests never fail locally, only on the VM?

Hmm, it is a good idea to check it, it not hard (I don't want to do it 😄):

1. add new project
2. copy flakiness tests
3. update xUnit assertion to NUnit/MsUnit
4. Start spamming in the fork

[timcassell]

I hope your PRs will be accepted before the Unity moves to .NET Core. Just two years left to wait 😭

Yeah it would be nice to unblock async engine support, but what does it have to do with Core in Unity?

[adamsitnik]

I've observed similar CI issues in the past in other projects. What is unique about most CI machines is that they have only one or two cores, so getting into a deadlock is way easier. You could try to reproduce it locally by running the tests affinized to 1 or 2 cores.

[YegorStepanov]

I hope your PRs will be accepted before the Unity moves to .NET Core. Just two years left to wait 😭

Yeah it would be nice to unblock async engine support, but what does it have to do with Core in Unity?

Since you are writing a library for Unity, I thought it was related to Unity.

Anyway, we need to support taskable object to support UniTask and UnityEngine.Awaitable/UnityTask without converting them to Task.

To do this, we need to slightly modify your AwaitHelper

[snowfrogdev]

@YegorStepanov any plans for this?

[timcassell]

@snowfrogdev Yegor is MIA, feel free to take over here.