Can you deadlock on calling GC.Collect and GC.WaitForPendingFinalizers?

Question

Given the following:

GC.Collect(GC.MaxGeneration);
GC.WaitForPendingFinalizers();
GC.Collect(GC.MaxGeneration);

Taking into account multi-threading and Garbage Collection modes, under what circumstances would you get a deadlock on WaitForPendingFinalizers?

Note: I am not looking for answers about the reasons why you shouldn't be calling GC.Collect.

Answer 1

// causes a deadlock when built with release config and no debugger attached
// building in debug mode and/or attaching the debugger might keep
// badIdea alive for longer, in which case you won't see the deadlock
// unless you explicitly set badIdea to null after calling Monitor.Enter

var badIdea = new BadIdea();
Monitor.Enter(badIdea);

GC.Collect(GC.MaxGeneration);
GC.WaitForPendingFinalizers();
GC.Collect(GC.MaxGeneration);

// ...

public class BadIdea
{
    ~BadIdea()
    {
        lock (this)
        {
            // ...
        }
    }
}

Answer 2

There is famous deadlock on WaitForPendingFinalizers, described by Jeffrey Richter. It is shown here: http://haacked.com/archive/2005/04/12/neverlockthis.aspx

class MyClass
{

private bool isDisposed = false;

    ~MyClass()
    {
        lock(this)
        {
            if(!isDisposed)
            {
                // ...
            }
        }
    }
}
...
MyClass instance = new MyClass();

Monitor.Enter(instance);
instance = null;

GC.Collect();
GC.WaitForPendingFinalizers();

It is caused by incorrect using of lock(this). Anyway, this is situation when WaitForPendingFinalizers is locked.