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.
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.