using statement on IDisposable object - delay of calling Dispose method

Question

As describe this article, about usage of using on IDisposable objects, it says one interesting words:

...using block, the Dispose method is automatically called sometime after the block ends. (It may not be immediate; it depends on the CLR.)

Interesting here is "It may not be immediate; it depends on the CLR". Can anyone provide more details on this? Because we have some strange situations where it seems that on code using(new MyDisposable()) {...}, after end of block } it does NOT immediately calls Dispose method on MyDisposable instance, but some time later.

UPDATE: Conclusion for me, it seems to me that i have problem elsewhere. I think that Dispose method can be called some time later after using block ends. But when it is not like that, than i must find problem somewhere else in my code. Thanks for responses!

Answer 1

using (SomeDisposableResource resource = new SomeDisposableResource())
{
    // TODO: use the resource
}

is equivalent to:

SomeDisposableResource resource = new SomeDisposableResource();
try
{
    // TODO: use the resource
}
finally
{
    if (resource != null)
    {
        ((IDisposable)resource).Dispose();
    }
}

so, up to you to draw conclusions. Everything depends on how you define immediate. In a multithreaded environment other actions could be performed between the try block and the disposal of the resource but as it is wrapped in a finally block it is guaranteed that the Dispose method will be called.