SpectrumBIM Gamut crashes Revit

[rossen.hristov]

Hello,

I am a developer at Chaos Group and I develop V-Ray for Revit. Recently a customer contacted us and told us that Revit crashes when V-Ray for Revit starts. The bad thing is that the stack trace indicates that crash occurs in the SpectrumBIM Gamut code so we can't really do anything to fix this. Are all Revit third-party assemblies loaded in the same ApplicationDomain? This seems to be the case.

There is V-Ray Next for Revit installed and when it starts SpectrumBIM Gamut crashes Revit.

When V-Ray Next for Revit starts, it loads a Grpc Server. This causes the Grpc assembly to be loaded. It appears that SpectrumBIM Gamut listens for the CurrentDomain.AssemblyResolve event and when it receives it it tries to do something. The the exception occurs. Unfortunately, I cannot fix anything because the code is not mine, but SpectrumBIM's, i.e. the crash happens in SPTR.Gamut.Revit.App.GamutApp.CurrentDomain_AssemblyResolve(Object sender, ResolveEventArgs args)

 Here is the full stack trace:

System.TypeInitializationException: The type initializer for 'Grpc.Core.Internal.PlatformApis' threw an exception. ---> System.IO.FileLoadException: Could not load file or assembly 'UnityEngine' or one of its dependencies. An argument was out of its legal range. (Exception from HRESULT: 0x80131502) ---> System.ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length
at System.String.Substring(Int32 startIndex, Int32 length)
at SPTR.Gamut.Revit.App.GamutApp.CurrentDomain_AssemblyResolve(Object sender, ResolveEventArgs args)
at System.AppDomain.OnAssemblyResolveEvent(RuntimeAssembly assembly, String assemblyFullName)
— End of inner exception stack trace —
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type)
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName)
at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
at System.Type.GetType(String typeName)
at Grpc.Core.Internal.PlatformApis..cctor()
— End of inner exception stack trace —
at Grpc.Core.Internal.PlatformApis.get_IsXamarinIOS()
at Grpc.Core.GrpcEnvironment.get_IsNativeShutdownAllowed()
at Grpc.Core.GrpcEnvironment.GrpcNativeInit()
at Grpc.Core.GrpcEnvironment..ctor()
at Grpc.Core.GrpcEnvironment.AddRef()
at Grpc.Core.Server..ctor(IEnumerable`1 options)
at Chaos.VRay4Revit.Addin.AssetEditor.AssetEditorServer.Start()

Chaos.VRay4Revit.Addin.AssetEditor.AssetEditorServer.Start() triggers the whole sequence of events but the crash occurs in SPTR.Gamut.Revit.App.GamutApp.CurrentDomain_AssemblyResolve

Has anyone encountered anything remotely similar, i.e. two completely different Revit addons cannot work together because all of their assemblies are loaded in one and the same application domain?

Bad news is that ALL third-party Revit add-ons execute in one and the same AppDomain. So if two different add-ons need a different version of the same .NET library I guess that the first one to load wins and the second has to pray everything works at all. Am I wrong? Here is the info: https://stackoverflow.com/questions/59501154/create-separate-appdomain-for-my-plug-in-on-revit

Thanks in advance.

[jeremytammik]

> Are all Revit third-party assemblies loaded in the same ApplicationDomain?

Yes.

Maybe splitting the conflicting add-ins into separate executables and using inter-process communication to let them cooperate will enable you to solve the problem?

https://thebuildingcoder.typepad.com/blog/2019/11/integrating-the-helix-3d-viewer-with-a-wpf-add-in....

[rossen.hristov]

The problem is that it is not our code (V-Ray for Revit) crashing, but another company's code (Gamut App) is crashing because we load the Grpc assembly, they listen for this event and then they crash. We have no control over their code! And our customers are blaming us (Chaos Group) that Revit crashes. Because this happens when V-Ray starts up and loads the Grps assemblies and then their addon throws an exception We can't fix something which is not ours.

How should we proceed in such a case? What should we tell them? What answer we should provide to a customer that says your software crashes Revit, when in fact it is not our software?

I should basically tell our customer to either choose SpectrumBIM Gamut or V-Ray for Revit because they cannot simultaneously live in the same App Domain in Revit.

Maybe Autodesk could log a feature request that every single add-on runs in its own isolated container, i.e. AppDomain?

Has Autodesk thought about that different add-ons might fight with each other and in case so what is the best thing to do? If two different add-ons want to use different versions of the same .NET library, lets sat Log4Net, what happens? The first one wins? With their version?

Is there a straightforward solution to a huge problem likes this?

In fact there might be even a security risk if someone develops a malicious add-on and tries to do funny stuff with other people's add-ons -- either directly or through reflection. Another idea to think about...

[jeremytammik]

Two solutions:

• Ensure that you use the version of the DLL that has been loaded, if one already has. Otherwise, do as you please.
• Use IPC to disconnect the add-ins from each other, so each one can do as it pleases.

This is the official recommendation provided by Autodesk to handle the situation with CefSharp:

https://thebuildingcoder.typepad.com/blog/2019/04/whats-new-in-the-revit-2020-api.html#4.1.1

[rossen.hristov]

"Ensure that you use the version of the DLL that has been loaded, if one already has. Otherwise, do as you please."

How can we possibly know what versions of many general purpose .NET libraries such as Google's Grpc are the other 100+ add-ons using? How can they know what version we are using?

I do not understand?

So I have to make sure I force-load my version of the .NET assembly as soon as possible as my add-on is loaded and if I have some luck my add-on to be loaded first, I will be the first one that does so and all other Revit add-ons, which use a different version of the same library should do as they please and maybe crash.

These are not .NET libraries used by Revit. These are general purpose .NET assemblies, i.e. Google Grpc, Log4net, etc. they can be hundreds.

Are the add-ons loaded in alphabetical order?

And what has CefSharp has got to do with this issue? We have two different add-ons and the one crashes because of the other. One is developed by us and the other one NOT by us. How does CefSharp  even come in play?

Should add-on developers communicate with each other and agree to use the same version of everything?

[rossen.hristov]

"Maybe splitting the conflicting add-ins into separate executables and using inter-process communication to let them cooperate will enable you to solve the problem?"

One is developed by Company A, the other by Company B. 

On these forums, no one is reading what is going on. We are simply provided with links to some existing posts which have almost nothing to do with the question in hand...

[jeremytammik]

Dear Rossen,

I read your description carefully and understand the problem.

I am sorry that I cannot help.

Sorry I mentioned the other aspects, that are of no use at all in your situation, just as you correctly point out.

[rossen.hristov]

I found the SpectrumBIM Gamut Code that crashes Revit:

private static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
        {
            string directoryName = Path.GetDirectoryName(typeof(GamutApp).Assembly.Location);
            string str = string.Concat(args.Name.Substring(0, args.Name.IndexOf(",", StringComparison.Ordinal)), ".dll");
            string str1 = Path.Combine(directoryName, str);
            if (!File.Exists(str1))
            {
                return null;
            }
            return Assembly.LoadFrom(str1);
        }

The call to Substring causes System.ArgumentOutOfRangeException: Length cannot be less than zero.
Parameter name: length

I contacted them SpectrumBIM. Unfortunately no one responds yet.

[rossen.hristov · Accepted solution]

Here is a full recap of what is going on:

1. Revit starts and loads all third-party addons
2. SpectrumBIM Gamut App starts and attaches an event listener for the AppDomain.ResolveAssembly event in which they try to load one of their assemblies in case it was not successfully loaded. What they do not suspect is that this event handler will be called for ALL assemblies that failed to load in this AppDomain -- not just theirs.
3. V-Ray for Revit starts and load the Grpc.Core.dll assembly. This assembly tries to load some "UnityEngine" assembly and fails but this is fine for V-Ray for Revit because we do not need it and everything is working properly.
4. The event that this UnityEngine assembly has failed to load reaches the SPTR.Gamut.Revit.App.GamutApp.CurrentDomain_AssemblyResolve event handler where they expect some comma in the name and of course there is no comma because this is about the UnityEngine assembly and of course the call to String.Substring throws bringing the entire Revit app down.
5. This exception prevents the Grpc assembly from loading and thus V-Ray can't start.

The only resolution is for SpectrumBIM Gamut to fix their event handler to expect all kinds of different assembly load failures or to uninstall their addon from Revit.

---OR---

Revit to provide a separate AppDomain for each addon, instead of throwing all of them to fight in the same AppDomain.