Parallelization of method calls to several VCProject instances

Question

Hello,

I'm writing a stand alone application, which uses the VCProjectEngine of VS2010 to read *.vcxproj files and processes the information of them (e.g. additional include directories or configurations for files). I use C++/CLI and VS2010 Professional. This works very well, but seems to be slow, because of the processing of the project information by me. Therefore I decided to use parallelization to speed it up.

I'm using the Parallel.ForEach loop, which calls the following method for every project path. In the ProcessProject method I access, evaluate and store the information of the project. The access to common data structures for storing the information is synchronized properly.

void EvaluateProject(String^ projectPath)
{
  VCProjectEngine^ projectEngine = gcnew VCProjectEngineShim();
  VCProject^ project = projectEngine->LoadProject(projectPath);

  ProcessProject(project);

  projectEngine->RemoveProject(project);

Now I'm experiencing several problems. First of all parallel loading of the projects doesn't seem to work properly. I get a System.InvalidOperationException (Collection was modified; enumeration operation may not execute.) in Microsoft.VisualStudio.Project.VisualC.VCProjectEngine.dll. I don't know why this problem occurres, since i create a new instance of the VCProjectEngine for every project I want to read. Therefore there shouldn't be synchronization problems.

Anyway I also tried to read all projects first and only process them in the Parallel.ForEach loop. Sadly this also results in several exceptions, which change every time I run the loop (as it is supposed to do due to nondeterministic threading). They occure in the assemblies of the VCProjectEngine, so i can't determine the cause of them. Some of the messages are about parameters, which are null, or entries, which are already in a dictonaries. I don't use a dictionary and no parameter is null. I think there might be some caching in the VCProjectEngine, which is not thread safe.

The documentation contains very less information about thread safety, so i need your help on that topic. Is there a way to use VCProjectEngine and threading?

Best regards

PS: Since VCProjectEngine is used for extensions, I posted in the Extensibility section. If this is wrong, please move the post to the correct section.

Answer 1

Hi John,

We know only Visual C++ project model object that can be returned by CoCreateInstance. If we load other type project via VCProjectEngine, the exception will be reported.

Are you sure the project you load is a C++ project?

Best regards,

---

Ego [MSFT]
MSDN Community Support | Feedback to us

Answer 2

Hi Ego,

thanks for your reply. When I try to load a non C++ project, I get a COMException. I'd already written a catch clause to handle it. I'm sorry for not including it in the example.

Since I don't receive any exceptions when running the mentioned method in a regular loop, I assume that there is a problem with threading in VCProjectEngine and the associated classes.

Therefore I think I need a way to create multiple instances of VCProjectEngine, which are separated from each other to avoid the threading problems or I have to get to know where I have to synchronize calls to the VCProjectEngine classes methods.

Best regards

Answer 3

Hi,

I think I forgot to post the question after the last part of my reply:

Does somebody know a way to create multiple instances of VCProjectEngine or to synchronize calls to a single instance in order to avoid the mentioned problems with threading?

Best regards