How to add a call to a non-static class member function to the threadpool?

Question

I'm looking for this stackoverflow: How to get Windows thread pool to call class member function? for C++/CLI: I have a ref class with a member function (a copy of that function is static for testing purposes):

ref class CTest
{
public:
  static void testFuncStatic( System::Object^ stateInfo )
  {
    // do work;
  }
  void testFunction( System::Object^ stateInfo )
  {
    // do work;
  }
};

From main() I can easily add a call to the static function to the threadpool:

System::Threading::ThreadPool::QueueUserWorkItem (gcnew System::Threading::WaitCallback (&CTest::testFuncStatic));

But I don't want to call the static function (which is more or less an object-independent global function), I want to call the member function testFunction() for several instances of the class CTest.
How can I achieve that?

score 3 · Accepted Answer · answered Aug 06 '13 at 13:03

3

In C++/CLI, you need to explicitly specify the object you want the delegate to call the function on.

ThreadPool::QueueUserWorkItem(gcnew WaitCallback(this, &CTest::testFunction));
                                                 ^^^^

answered Aug 06 '13 at 13:03

David Yaw

27,383
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@ David: `this` doesn't work because in main() there is no `this`, but you've put me on the right track, Thank you!! The solution: CTest^ ctest01 = gcnew CTest; ThreadPool::QueueUserWorkItem (gcnew WaitCallback (ctest01, &CTest::testFunction)); – Tobias Knauss Aug 06 '13 at 13:19

score 1 · Answer 2 · answered Aug 06 '13 at 19:53

1

You should not use thread pools in .NET. You should consider to use System::Threading::Tasks. This is an even more efficient way to use multiple "Tasks"...

Also be aware of the new "async" keyword in C#4.5. This helps a lot! So you should really consider to put the .NET part of your application into C#... and only use C++/CLI for InterOp scenarios.

answered Aug 06 '13 at 19:53

Jochen Kalmbach

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The Task-Paralell-Library is more efficient that the "QueueUserWorkItem"... See also: http://blogs.msdn.com/b/pfxteam/archive/2009/10/06/9903475.aspx Conclusion: Task is now the preferred way to queue work to the thread pool. See also: http://stackoverflow.com/questions/16252217/is-there-a-difference-between-threadpool-queueuserworkitem-and-delegate-begininv http://stackoverflow.com/questions/9200573/threadpool-queueuserworkitem-vs-task-factory-startnew – Jochen Kalmbach Aug 07 '13 at 08:08

score 1 · Answer 3 · answered Nov 04 '15 at 07:54

1

Try this:

CTest ^ ctest = gcnew CTest;
ThreadPool::QueueUserWorkItem(gcnew WaitCallback(ctest, &CTest::testFunction));
                                                 ^^^^^

WaitCallback(ctest provides memory context to allocated object of CTest &CTest::testFunction)); provides memory shift to actual allocated function memory address of testFunction.
'Dynamic' functions are part of 'dynamic' class object.
This must be like that because of garbage collector.

answered Nov 04 '15 at 07:54

MrHIDEn

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Did you copy my comment from a 2 years old answer? – Tobias Knauss Nov 04 '15 at 08:07
No! I just faced this problem. I did an experiment and after success I post this here. I read only answers, I did not see your comment. Can you post it as answer? I will remove my answer? I am sorry. – MrHIDEn Nov 04 '15 at 08:23
No, it's fine, you can keep yours. – Tobias Knauss Nov 04 '15 at 08:38

How to add a call to a non-static class member function to the threadpool?

3 Answers3